Available online: www.notulaebiologicae.ro
Print ISSN 2067-3205; Electronic 2067-3264
AcademicPres
Not Sci Biol, 2018, 10(3):410-423. DOI: 10.15835/nsb10310287
Notulae Scientia Biologicae
Review Article
Yellow Rust (Puccinia striiformis): a Serious Threat
to Wheat Production Worldwide
Siham KHANFRI, Mohammed BOULIF, Rachid LAHLALI*
Ecole Nationale d’Agriculture de Meknès, Phytopathology Unit, Department of Plant Protection and Environment, Km10, Rte Haj Kaddour,
BP S/40, Meknès 50001, Morocco; rlahlali@enameknes.ac.ma (*corresponding author)
Abstract
Wheat (Triticum sp. L.), as one of the first domesticated food crops, is the basic staple food for a large segment of
population around the world. The crop though is susceptible to many fungal pathogens. Stripe rust is an important airborne
disease caused by Puccinia striiformis (Pst) and is widespread wherever wheat is cultivated throughout the world, in temperatecool and wet environments. The causal fungus of stripe rust or yellow rust is an obligate parasite that requires another living
host to complete its life cycle. Pst includes five types of spores in the life cycle on two distinct hosts. Stripe rust is distinguished
from other rusts by the dusty yellow lesions that grow systemically in the form of streaks between veins and on leaf sheaths.
The importance and occurrence of stripe rust disease varies in cultivated wheat, depending on environmental conditions
(moisture, temperature, and wind), inoculum levels and susceptible host varieties. Transcaucasia was previously thought to be
the center of origin for the pathogen. However, new findings further underlined Himalayan and near-Himalayan regions as
center of diversity and a more tenable center of origin for P. striiformis. Long-distance dispersal of stripe rust pathogen in the
air and occasionally by human activities enables Pst to spread to new geographical areas. This disease affects quality and yield of
wheat crop. Early seeding, foliar fungicide application and cultivation of resistant varieties are the main strategies for its
control. The emergence of new races of Pst with high epidemic potential which can adapt to warmer temperatures has
expanded virulence profiles. Subsequently, races are more aggressive than those previously characterized. These findings
emphasize the need for more breeding efforts of resistant varieties and reinforcement of other management practices to
prevent and overcome stripe rust epidemic around the world.
Keywords: epidemiology; management; Puccinia striiformis; stripe rust; wheat
Introduction
Wheat represents approximately 19% of global major
cereal crop production. East African countries, North
Africa and Middle East consume over 150% of their own
wheat production and are heavily dependent on imports to
meet their food security (FAOSTAT, 2018). Demand for
wheat in the world continues to grow rapidly with
increasing population growth. It is predicted that the world
population will surpass 8 billion by 2025 and the demand is
expected to increase to 760 million tons by 2020 and exceed
880 million metric tons by 2050 (Dixon et al., 2009), thus
the production needs to increase at least by 50% by the year
2025 (Yadav et al., 2017).
Crop production throughout the world is reduced
significantly by biotic and abiotic stresses. Diseases reduce
approximately 14% of world crop production. Wheat is
susceptible to many pathogens including stem rust caused
by Puccinia graminis f.sp. tritici, leaf or brown rust caused by
P. triticina and stripe or yellow rust caused by P. striiformis
f.sp. tritici (Pst); they are the most important diseases of
wheat which cause important losses of yield (Ellis et al.,
2014). Among rust diseases affecting wheat, stripe rust was
considered to be the most the most destructive (Chen,
2005; Hovmoller et al., 2011). This disease can cause
significant reductions in yield and result in total losses of the
production (Ali et al., 2017). The use of resistant cultivars,
chemical substances and early seedling are the main
methods for the control of this disease.
Stripe rust causes many challenges to farmers around the
world because the majority of winter wheat cultivars are
either susceptible or possess low level of resistance to this
disease (Sharma et al., 2016). Until now, stripe rust on
susceptible wheat cultivars is mainly controlled by fungicide
Received: 26 Apr 2018. Received in revised form: 24 Aug 2018. Accepted: 24 Sep 2018. Published online: 27 Sep 018.
Khanfri S et al / Not Sci Biol, 2018, 10(3):410-423
411
applications. Different fungicides were used to control the
stripe rust significantly, but their efficacy was shown to
differ according to their applied concentrations (Conner et
al., 1988). Furthermore, the most significant problem
encountered in the control of this disease by farmers was the
optimum periods of fungicidal applications because any lack
of these chemical treatments might lead to the important
losses of yield. Among fungicides used to control stripe rust,
researchers assayed different active ingredients at different
concentrations rate such as epoxiconazole, pyraclostrobin,
and propiconazole and found their efficacies are highly
correlated with their applied concentrations (Sharma et al.,
2016). In most reported cases, preventive treatments were
more efficient (Boshoff et al., 2003). Although chemical
treatments are efficient in avoiding a stripe rust epidemic
and contributed efficiently in preserving yield, their use is
still criticized and not suitable due to their higher cost and
their adverse effects on both environment and human
health. To date, thousands of studies were conducted on the
epidemiology and control of stripe rust. The present
overview aimed at providing a basic understanding of the
epidemiology and control of wheat yellow rust. Therefore,
this review emphasizes the following areas: wheat stripe rust
biology and development; migration and introduction of
the pathogen; economic importance; stripe rust
management; and current state and challenges.
Wheat (Triticum spp.) taxonomy and biology
Wheat is one of the important crops worldwide that
ranks third behind corn and rice (Asseng et al., 2011). It was
cultivated for over 8,000 years (Curtis, 2002) providing the
basic nutritive elements (carbohydrates, proteins, vitamins,
minerals and fiber) to humans. More than 4.5 billion people
in 94 developing countries depend on food products made
from wheat in addition to rice and maize (Shiferaw et al.,
2011).
Fig. 1. Evolution of domesticated wheat (Peng et al., 2011)
Wheat is a C3 plant that is well suitable to cool
environment and adapted to a broad range of climates: from
wet temperate to dry and high rainfall areas, and from
warm- humid to dry- cold environment (Acevedo et al.,
2006). The optimum growing temperature for wheat lies
between 18 °C and 24 °C and the minimum and maximum
growth temperatures range from 3 °C to 4 °C and from 30
°C to 32 °C respectively (Getie, 2015). In addition, wheat is
of two types based on the sowing season: spring wheat and
winter wheat. Unlike spring wheat, which has a short period
of vernalisation, winter wheat requires a long period of cold
temperatures for flowering (Curtis et al., 2002).
Some researchers classify wheat within the genus of
Triticum that is a part of the Poaceae family. According to
the number of chromosomes pairs, wheat is further
subdivided into many species. Furthermore, an accurate
taxonomical classification for wheat species is necessary for
the breeding purposes and conservation of wheat
biodiversity. Goncharov’s classification has 29 species; six of
them are synthetic species (Fig. 1) (Goncharov et al., 2009).
Wheat production in the world and in Morocco
Wheat is the largest grown crop in the world with a 22%
of the total arable land in the world (Leff et al., 2004). In
2015/2016, wheat world production reached 734Mt and it
is estimated to reach 757Mt during the growing season
2017-2018 (FAO, 2018). The European Union is the
largest producer of the wheat (Siad et al., 2017) with 155
million tons in 2014, followed respectively by China (126
million tons), India (95 million tons), Russia (59 million
tons), United States (55 million tons), Canada (29 million
tons), Australia (26 million tons), Ukraine (24 million tons)
and Argentina (12 million tons). The major exporters of
wheat are the United States, Canada, Australia, the
European Union, Russia, Ukraine and Argentina (USDA,
2014).
Khanfri S et al / Not Sci Biol, 2018, 10(3):410-423
412
Morocco presents suboptimal agro-meteorological
conditions for wheat growing (Mrabet, 2000). The wheat
growing regions can be classified into 6 agro-ecological
regions (Gommes et al., 2009), ranging from a typical
Mediterranean climate in the Northern coasts to
continental conditions in the Central regions and in the
mountainside areas in the West High Atlas, and to semiarid environments in the Southern part of the wheatcropped area at the North of the Sahara (Confalonieri et al.,
2013). Soft wheat production is concentrated in the
Atlantic plains of Morocco, from semi-arid to sub humid
provinces, whereas durum wheat is mainly grown in the
semi-arid southwestern plains (Balaghi et al., 2012).
A total of 7.1 million tons of wheat was harvested in
2017 in Morocco, which represents an increase of 33%
above the average yield of the five previous years (FAO,
2017). The cereals sector is a fundamental sector of
agricultural production in Morocco. Cereal production
contributes about 15-20% of the Moroccan gross
agricultural product. It plays an outstanding role in terms of
the annual grain-sown areas of arable land, rural
employment and the utilization of processing industry (El
Mekki, 2006).
In Morocco, wheat is the most consumed cereal; its
consumption for 2016-2017 was estimated at 10.2 MMT.
Morocco’s High Commission for planning (HCP)
estimated wheat consumption at 216 kg per capita annually
(USDA, 2017). Morocco is one of the world’s major
importers of wheat. Its imports requirements of common
and durum wheat are forecasted to reach 4.5 million tons in
2017-2018. EU and Black Sea countries are the top
exporters of the common wheat to Morocco, while Canada
is the top supplier of durum wheat (FAO, 2017). According
to FAS/Rabat, Morocco forecasted the harvested area of
wheat for 2017 at 3.3 million hectares (USDA, 2017).
Wheat stripe rust disease
The causal agent of stripe rust, also known as yellow rust,
belongs to the order of Pucciniales of the Basidiomycota. It
is an obligate parasite that requires another living host to
complete its life cycle. Puccinia striiformis Westend. f.sp.
tritici is the fungal pathogen responsible for the disease and
it was coined by Hylander et al. (1953) and later reviewed
by Cummins and Stevenson (Line, 2002). This
nomenclature had undergone several changes and was given
various names such as Uredo glumarum (Schmidt, 1827),
Puccinia striaeformis (Westendorp, 1854), Puccinia
straminis (Fuckel 1860), Puccinia glumarum (Eriksson and
Henning 1894) (Chen, 2005).
The life cycle of Puccinia striiformis
Like many rust fungi, P. triiformis (Pst) alternates
between hosts during its life cycle (Fig. 2) and has separate
hosts for asexual and sexual phases (Berlin et al., 2017). Pst
includes five types of spores in the life cycle (Schwessinger,
2017) on two taxonomically unrelated hosts; it alternates
between a graminaceous host for asexual reproduction and
barberry where sexual reproduction may occur (Jin et al.,
2010). Urediniospores and teliospores of the fungus are
dikaryotic, whereas teliospores produce haploid
basidiospores (Chen, 2005).
Fig. 2. The life cycle of Puccinia striformis f.sp. tritici (Zheng et al., 2013)
Khanfri S et al / Not Sci Biol, 2018, 10(3):410-423
413
Pycnial and aecial spore stages of the fungus were
recently confirmed (Jin et al., 2010). The diakaryotic phase
of the life cycle is confined to the primary host (wheat),
upon which urediniospores, teliospores and basidiospores
are produced. As the nutrient supply from the infected
tissues declines, the telia stage is initiated. Teliospores
overwinter on residual senesced tissues and germinate the
following spring to produce four haploid basidiospores that
infect the alternate host (Berberis spp.) ( Sørensen, 2012;
Baily, 2013) upon which pycniospores and aeciospores are
produced on the upper and lower leaf surface, respectively
(Jin et al., 2010).
Infection process and infection structure
Because of some limitations of the staining and
microscopy techniques, an accurate description of how
stripe rust fungus infects its hosts was not given until 1981
by Cartwright and Russell. They used fluorescence
microscopy to observe the fungal structures in the whole
leaves of both seedlings and adult plants. Their findings
showed that urediniospores of P. striiformis infect wheat by
entering the leaf through stomata. Spores germinate and
form a germinative tube that grows and moves along the leaf
to enter through the opening stomata (Cartwright et al.,
1981; Sørensen, 2012).
Unlike other rust fungi, P. striiformis does not
differentiate an appressorium (Moldenhauer et al., 2006).
The germinative tube entrance initiates the formation of
primary infection hyphae in the stomatal cavity and a
contact of primary infection hyphae with mesophyll or on
epidermal cell induce the formation of a haustrial mother
cell (hmc). A haustorium is established between the cell wall
and the plasma membrane of the host cell (Ma et al., 2009;
Sørensen, 2012). The secondary infection takes place, in
which hyphae start developing from the primary infection
hyphae and leads to the formation of an extensive hyphal
network in the mesophyll layer. Approximately one week
after the infection, the host response may appear, resulting
in visible chlorotic spots appeared at the leaf surface. One
week after, sporulation starts and the distinctive yellow
spores will appear on leaf (Chen, 2005; Sørensen, 2012).
The optimum temperature for germination of the
spores is 10-12 °C. High temperature inhibits sporulation
or force the fungus to enter dormancy. Under optimum
conditions, the time between inoculation and sporulation is
12-13 days (Line, 2002).
Host range
Wheat and barley are the major hosts of P. striiformis.
The host range of stripe rust fungus includes 320 grass
species, which are from up to 50 genera belonging to
subfamilies of Festucoideae and Eragosteae. Aegilops,
Agropyron, Bromus, Elymus, Hordeum and Triticum are the
main genera that are affected by stripe rust (Brar, 2015).
Puccinia striiformis has been categorized into formae
speciales based on specialization on different genera and
species of host plants (Chen, 2005). Until now, six formae
speciales were reported; five were named by Eriksson (1894)
and more recently, Wellings et al. (2004) added a new
forma specialis on Hordeum spp. discovered in Australia
(Line, 2002). The relationship between P. striiformis f.sp.
tritici and P. striiformis f.sp. hordei is not clear because they
overlap their host range by infecting barley and wheat,
respectively (Chen, 2005). For such anomalies, Gassner and
Staib (1932) preferred to remain with race description and
avoid the use of formae speciales (Chen, 2005).
Disease symptoms on wheat and alternate hosts
All growth stages of the plant are susceptible to infection
(Line, 2002). Initial symptoms of stripe rust appear about
one week after infection as small, yellow spots or flecks on
the leaf sheaths. These spots develop into long and narrow
stripes on leaf sheaths, glumes and awns (Fig. 3). Mature
pustule will break open and release yellow-orange masses of
urediniospores. The infected tissues may become brown and
dry when plants begin to senesce or become stressed. The
pathogen reduces plant vigor because it removes plant
nutrients and water, and result in desiccation of leaves.
Severe early infection can result in plant stunning (Line,
2002; Chen, 2005; Singh et al., 2017).
The basidiospores, produced by germinating teliospores,
infect barberry (Berberis spp.) leaves and produce pycnia on
the upper surface and acia on the lower surface (Fig. 4).
Symptoms appear also on Oregon grape (Mahonia
aquifolium), another alternate host of Pst. Similarly, pycnia
and aecia are produced on the upper and lower side of leaves
respectively (Wang et al., 2013).
Fig. 3. Stripe rust symptoms observed on soft wheat cultivar ‘Arrehane’ during the growing season 2017-2018 at the experimental
field (ENAM, Meknes, Morocco)
Khanfri S et al / Not Sci Biol, 2018, 10(3):410-423
414
Fig. 4. Disease symptoms on Oregon grape (Mahonia aquifolium): pycnia (A) and aecia (B) produced on the upper and lower side
of leaves respectively (Wang et al., 2013)
Races pathogens on wheat
There are two levels of specialization of P. striiformis;
specialization between different genera and specialization in
a single host at the genotype level. The second level of
specialization, which divides Pst into races, is based on
avirulence or virulence level to cultivar or genotype of wheat
lines. Allison and Isenbeck (1930) were the first to define
race concept based on the qualitative rust infection types.
However, the host specificity of wheat genotypes was first
recognized by Hungerford and Owens (1923) (Hovmoller
et al., 2011).
Pathogen virulence
There are two distinct types of pathogenic races: those
that interact with host varieties, and those that do not (Van
der Plank, 1969). The gene for gene relationship is based on
specific interactions between the genotype of the host and
the genotype of pathogen. Van der Plank termed this type of
interaction by vertical resistance. When differential
interaction is absent, we talk about horizontal resistance
(Brar, 2015).
The release of new more durable resistant cultivars is
usually based on a better understanding of virulence
variation and host-rust interaction (Webb et al., 2006). The
mechanisms by which new races have appeared in Pst are
unclear. High reproduction, capability of long distance
dissemination and adaptation to various host species and
environments, make Pst a highly variable pathogen (Wan et
al., 2017).
Molecular characterization using various markers has
generated numerous datasets to gain more understanding of
mechanisms of variation in the pathogen population and
determination of pathogen reproduction. It was conducted
to collect information, which was otherwise impossible to
generate through virulence characterization. Sequencing
technologies had circumvented many limitations and had
provided a rich source to study virulence variation and
evolution of the stripe rust pathogen (Liu et al., 2012;
Zheng et al., 2013).
The pathogen produces new races and genotypes
through different mechanisms. Mutation was considered as
the most important mechanism in generating new virulent
races (Waqar et al., 2018). The pathogen can also produce
new races through somatic recombination, sexual
recombination and natural reproduction. Recent results
suggest that genetic recombination contributes greatly to
genomic diversification of Pst. Subsequently, high levels of
genetic variation were observed in Pst populations from
Western China and central Asia, where susceptible Berberis
species are widely distributed (Zheng et al., 2013). This
mechanism is still unclear (Waqar et al., 2018).
Disease development
When pathogen inoculum and susceptible host are
present, the development of wheat stripe rust disease
depends even more on weather conditions such as moisture,
temperature and wind (Chen, 2005).
Spore germination, infection and survival of Pst, are
directly affected by moisture. A continuous period of three
hours of moisture is required for urediniospores
germination and infection. A relative humidity near to
saturation before inoculation increases rates of spore
germination considerably (Line, 2002). Precipitation,
especially light rains provide conducive conditions for
infection. However, high moisture can also negatively affect
spore viability. Spores kept in high moisture conditions lose
their viability more quickly than those kept under dry
conditions, because they lack the ability to induce
fungistasis. Spores dispersal is also affected by moisture.
Individual or cluster dispersal of urediniospores depends on
the level of relative humidity. Cluster dispersal is limited on
high humidity (Chen, 2005).
Temperature also influences the germination, infection
and survival of spores. Spores are capable of germinating
between 2.8-21.7 °C. However, they germinate most easily
at 10-12 °C (Line, 2002). Sporulation can occur at 5-20 °C.
Latent period, the time elapsing between infection process
and sporulation, is estimated to be about 10-15 days at 1219 °C. The latent period of stripe rust can last up to 180
days at temperatures near to freezing (Sørensen, 2012).
Lower temperatures adversely affect winter survival of the
pathogen. Pathogen development could be stopped in
Khanfri S et al / Not Sci Biol, 2018, 10(3):410-423
415
temperatures below -10 °C (Chen, 2005). High
temperatures above 30 °C limit pathogen development and
survival. Infections are more likely to occur at night, where
both dew formation and cool temperatures occur together
(Sørensen, 2012).
Wind inhibits spore germination by decreasing the
moisture content of inoculum. Therefore, the infection rate
is reduced, while the viability of the inoculum is increased.
Wind also facilitates the spread of the inoculum over new
territories and controls the time, rate and extent of
infection. Long distance dispersion of stripe rust by the air
resulted in its reintroduction and widespread (Chen, 2005).
Migration and introduction of the pathogen
Rusts are among the most devastating diseases of wheat
in many regions in the world (Singh et al., 2004). Yellow
(stripe) rust on wheat is present in most wheat growing
regions (Chen, 2005).
The first records of yellow rust in the USA were in 1915,
but there were no potentially serious outbreaks until 1960’s
which were reported in the western states (Line, 2002).
Yellow rust first appeared in Eastern Australia in 1979 , and
then spread to New Zealand in 1980 (Wellings et al., 1987).
Yellow rust was reported for the first time in South Africa in
1996 and 8 years after to Western Australia, the genotype of
this new fungal isolate suggesting that it may be derived
from East Africa (Boyd, 2005).
Rusts are widespread diseases across all major wheat
growing regions with diverse cropping systems, growing
seasons and germplasm traits (Singh et al., 2004). The three
rust pathogens differ in their climatic adaptation. Stripe rust
was reported to be prevalent in cooler and wetter regions,
temperate and maritime regions, and high elevation.
However, recent disease outbreaks, which have hit many
countries closer to the equator, suggest a new level of
adaptation.
Stripe rust is widely distributed across all continents
except Antarctica (Fig. 5). Its epidemics have become more
frequent in the USA (particularly the Pacific Northwest
region of North America), South America, North Africa
(Morocco, Algeria and Tunisia), East Africa (Ethiopia and
Kenya), East Asia (Northwest and Southwest China),
South Asia (India, Pakistan and Nepal), Australasia
(Australia and New Zealand), the Nile Valley and Red Sea
(Egypt and Yemen), West Asia (Lebanon, Syria, Turkey,
Iran, Iraq and Afghanistan,), Central Asia (Kyrgyzstan,
Uzbekistan, Tajikistan and Turkmenistan), Caucasus
(Georgia, Armenia and Azerbaijan) and Europe (UK,
Northern and Southern France, the Netherlands, Northern
Germany, Denmark, Spain and Sweden) (Solh et al., 2012).
Transcaucasia was suggested by Hassebrauk (1965) and
later by Stubbs (1985) as the center of origin for Pst. Recent
studies of Pst populations reported highest levels of genetic
diversity and recombinant population structure in
Himalayan and near-Himalayan region. These findings
supported the region as most likely the center of origin and
diversity for P. striiformis (Ali et al., 2014; Thach et al.,
2016).
Pathogen dispersal
Long distance dispersal (LDD) is an important
mechanism facilitating the colonization of new habitat. It
permits for many organisms to migrate between summer
and winter habitats (Brown et al., 2002). The comparison of
disconnected populations of yellow rust and dispersal data
showed that Pst can undergo long distance dispersal (Ali et
al., 2014).
World population’s distribution of Pst showed evidence
of international migration (Fig. 6). Pst populations studies
confirmed the NW Europe as the putative source of North
American (1900), South American (20th century) and
Australian (1979) populations.
Fig. 5. Worldwide geographical distribution of stripe rust (Brar, 2015)
Khanfri S et al / Not Sci Biol, 2018, 10(3):410-423
416
ABC analyses of Pst worldwide populations showed that
NW European population is the result of an admixture
event between China and Pakistan population. Thus, it was
suggested that Pst has spread from China to NW Europe
through human interventions. The recently spreading of
aggressive isolates is a real world example of stepwise
regional dispersal of stripe rust pathogen (Ali et al., 2014).
Viability of spores is influenced by humidity. Spores
need to withstand dry weather to survive and travel long
distances. Besides, urediniospores are dispersed by rain and
dissemination of spores by rain splash aids in quick dispersal
of the pathogen. Above all, wind dispersal allows stripe rust
pathogen to travel for long distances. The timing, type, and
direction of winds determine the earliness, scale and
development rate of stripe rust epidemics (Chen, 2005).
cultivars at that time (McIntosh et al., 2009). Losses of
nearly 2.25 million US $ were estimated in the 1998 in
South Africa (Pretorius, 2004). In China , a widespread
stripe rust epidemic affected about 6.6 million hectares of
wheat in 11 provinces during the growing season 20012002, causing a yield loss of 13 M tones (Wan et al., 2004).
Substantial losses were reported between 1999 and 2000 in
central Asia with a yield losses ranged from 20 to 40%
(Morgounov et al., 2004). In Australia, fungicide costs was
estimated to 40 million AU$ in 2003 (Wellings et al.,
2004). The most severe yield losses recorded in the USA
were estimated in more than 9 M bushels of wheat in 2000,
when the disease appeared in at least 20 states (Markell et
al., 2008).
Stripe rust losses
Stripe rust of wheat is the most important rust pathogen
of wheat worldwide and because the disease attacks from
early in the growing season, plants are usually stunted and
weakened, causing severe yield losses up to 70%. The disease
reduced yield, quality and size of the harvested grains. On
susceptible varieties, disease development at the seedling
stage can cause total yield loss (Chen, 2005). However, the
severity of stripe rust depends on host resistance, time of
initial infection, rate of disease development and disease
duration. According to Doling and Doodson (1968) and
Roelfs (1978), losses of up to 20% and 75% in wheat were
reported in the USA. Based on greenhouse experiments, a
potential yield loss up to 65% was recorded on a susceptible
cultivar (Wellings, 2011).
A large epidemics of wheat stripe rust occurred in other
regions in the world including North Africa and the Middle
East in the 1970s (Saari et al., 1985). These epidemics
occurred because of the presence of Yr2 gene in most of the
Stripe rust management
Using plant resistance
Using resistant cultivars is the most efficient, economic,
and environmentally safe approach to control rust diseases.
To date, more than 187 rust resistance genes were described
(Aktar-Uz-Zaman et al., 2017).
More than half a million wheat genetic resources and
their wild relatives are conserved in gene banks all over the
world. Discovering their favorable genetic diversity for
breeding is crucial for enhancing grain yield potential
needed to avert future food shortages (Longin et al., 2014).
The genus Triticum comprises three ploidy levels (Fig. 7)
and approximately 30 species (Feldman et al., 2012). Harlan
and de Wet (1971) developed a concept of gene pool and
decided it would be useful to divide the crop gene pool into
different pools, which allowed phylogenetic separation of
the germplasm based on introgression rates that can
potentially occur between the cultivated crops and their
ancestors (Harlan et al., 1971).
Fig. 6. Origin and migration routes of recently emerged populations of wheat yellow rust pathogen identified or confirmed
through population genetic analyses of a worldwide representative set of isolates (Ali et al., 2014)
Khanfri S et al / Not Sci Biol, 2018, 10(3):410-423
417
Fig. 7. Wheat gene pool representing various species (Pratap et al., 2014)
The primary gene pool consists of all biological species,
including cultivated races, wild and weedy relative forms of a
crop species. Gene transfer from the primary gene pool is
easy and F1-hybrids are fertile with normal chromosome
pairing. Biological species from the secondary gene pool
hybridize with the primary gene pool with some difficulty.
In the tertiary gene pool, gene transfer is very difficult and
requires special methods. Secondary and tertiary gene pools
represent a wide and yet little exploited reservoir of desirable
alien genes that can be incorporated with some difficulty
into cultivated wheat genotypes (Feuillet et al., 2009; Pratap
et al., 2014).
Wild relatives of wheat may be a rich resource for new
resistance genes for stripe rust. Thus widening the genetic
base is a priority and primary target to improve the
resistance of wheat varieties to cope with changing races of
Pst is the preferred strategy for achieving global wheat
demand (Cox, 1997).
Plant disease resistance genes
To date, 78 stripe rust resistance genes (Yr1-Yr78) were
officially been catalogued according to the 2017 Catalogue
of Gene Symbols for Wheat (McIntosh et al., 2010). The
symbol 'Yr' is used to designate specific resistance gene
against stripe rust.
Stripe rust resistance genes were introduced into
hexaploid wheat either by recombination with species
within the primary wheat genepool, or by introgression of
translocated chromosomes segments from secondary and
tertiary gene pools. Many stripe rust resistance genes were
linked to genes resistant to other fungal pathogens, such as
Yr9 linked to Lr 26/Sr31/Pm8, and Yr17 linked to
Lr37/Sr38 (Sharma, 2012). Most of the stripe rust
resistance genes were derived from common wheat
(Triticum aestivum), although some were derived from
different wild species, such as Triticum spelta album,
Triticum dicoccoides, Triticum spelta, Secale cereale, Aegilops
comosa, Aegilops ventricosa, Triticum tauschii and Haynaldia
villosa (Aktar-Uz-Zaman et al., 2017).
According to the Federation of British Plant
Pathologists (1973), resistance in general, has been defined
as “the ability of an organism to withstand or oppose the
operation of, or to lessen or overcome the effects of an
injurious or pathogenic factor”.
A basic compatibility (pathogenicity factors) between a
plant and pathogen is required for a pathogen to recognize
and overcome the nonhost or basic resistance of the host.
The capacity of a pathogen to cause disease is called
virulence and the plant response is susceptible. The
incapability to cause disease is named avirulence where the
plant response is resistant (Surico, 2013).
The gene-for-gene concept: according to Flor (1964 and
1971) studies, the gene-for-gene concept is based on the
observation that for each resistance gene (R) in the host
there is a corresponding a virulence gene (Avr) in the
pathogen. The interaction between the two genes leads to
hypersensitive reaction (HR) resulting to incompatibility
(Higgins et al., 1998). Based on Flor’s definition, Person
(1959) defined this concept as follows “where a hostpathogen relationship exists when the presence of a gene in
the host is contingent on the presence of a gene in the
pathogen, and where the interaction between the two genes
leads to a single phenotypic expression”. Thus, the presence
or absence of the relevant gene in either organism may be
recognized (Hysing, 2007).
Race specific resistance is also referred to as a major gene
resistance, gene for gene resistance, or seedling resistance.
Race-specific resistance genes are recognized by the presence
of low infection types (Rajaram et al., 2002). Resistance
extends from seedling stage into adult stages. Race specific
resistance is controlled by major genes (genes with major
effects), and it often “breaks down” easily with the
occurrence of new pathotypes of a pathogen (McDonald et
al., 2002; Knott, 2008).
Race nonspecific resistance: this type of resistance is
controlled by the interaction of a few or several genes having
minor to intermediate effects. In race nonspecific reaction
there is a reaction of one host genotype to different
Khanfri S et al / Not Sci Biol, 2018, 10(3):410-423
418
pathogen isolates. The genetic nature of this type of rust
resistance is usually complex (Francisco et al., 2001).
Vanderplank (1963) used the terms vertical resistance and
horizontal resistance for 'specific' and 'non-specific'
resistance, respectively (Al-Khayri et al., 2016).
Slow rusting: is a type of resistance, in which disease
develops slowly, resultingin intermediate to low disease
levels against all pathotypes of a pathogen. Effect of slow
rusting gene is characterized by longer latent period, low
susceptibility or infection frequency ,smaller uredial size,
reduced duration of sporulation and lower density of spore
production, that can affect disease progress in the field (Ellis
et al., 2014; Kumar et al., 2015).
Durable resistance: Johnson (1988) defined durable
disease resistance as “resistance that has remained effective
while a cultivar possessing it was widely cultivated in an
environment favoring the disease”. Durable resistance
sometimes represents the adult plant resistance (APR),
which is associated by combinations of several minor genes
acting additively and shows non-hypersensitive reactions.
However, some APR genes provide partial resistance that is
effective against specific races of a given pathogen species i.e.
race specific. The French bread wheat variety “Camp remy”
was an example of varieties with resistance to stripe rust,
grown and remained resistant to all pathotypes of Pst for
more than 20 years (Mallard et al., 2005).
Type of resistance to strip rust
In general, resistance to stripe rust is categorized as
seedling resistance (Table 1) , which can be expressed in all
stages, also referred as to as all stage resistance and adult
plant resistance, which express in adult stages (Chen, 2005;
Bulli et al., 2016). Seedling resistance and some types of
adult plant resistance are race specific resistance and they
come with risk of emergence of new more virulent races due
to high selection pressure on the pathogen (Chen, 2005; Jin
et al., 2010; Wellings, 2011).
High temperature adult plant resistance (HTAP)
(Table 1) is a nonspecific type of resistance, which becomes
increasingly effective with high temperatures and when
plants grow old. HTAP has proven to be more durable than
seedling resistance. However, HTAP resistance is
susceptible to all races of Pst at early stages of wheat
development (Chen, 2005, 2013). The combination of
non-race specific HTAP and race-specific all-stage
resistances is suggested to be the most effective approach for
controlling the disease because all-stage resistance can
provide high levels of resistance, until new virulent races
circumvent and HTAP resistance can reduce damage when
the all-stage resistance is overcome by new races (Chen,
2005).
The molecular markers and marker assisted selection has
produced very favourable results in facilitating mapping
genes to stripe rust and. In contrast, gene-pyramiding using
conventional methods is difficult, time-consuming and
requires concurrent tests of the same wheat breeding
materials with several different rust races before making a
selection (Aktar-Uz-Zaman et al., 2017).
More recently developed types of molecular markers,
such as random amplified polymorphic DNA (RAPD),
simple sequence repeat (SSR) markers and amplified
fragment length polymorphism (AFLP), are used to
characterize and compare rust populations (Chen, 2005).
Molecular markers are available for Yr5, Yr9, Yr10, Yr15,
Yr18, Yr24, Yr26, Yr28, Yr32, Yr33, Yr34, Yr36, YrH52
and Yrns-B1. The clone of a gene like sequence for
resistance to disease was developed for Yr17; it is a similar to
the resistance gene analog polymorphism (PGAP) (Chen,
2005).
Using fungicides
Fungicide application is a necessary approach to fight
against stripe rust disease (Line, 2002; Chen, 2005; Wan et
al., 2007). Various synthetic substances were applied to
control this disease. Commercial fungicide products were
used worldwide. They include Tilt, Evito, Quadri, Prosaro,
Stratego and Quilt (Chen, 2007). Currently, the following
active ingredients are labelled for control of stripe rust in
Morocco: propiconazole, azoxystrobin, propiconazole in
combination with trifloxystrobin, strobilurin and
azoxystrobinin combination with propiconazole. These
labelled fungicides with different active ingredients provide
choices for growers to use and may reduce selection pressure
in the fungal pathogen to develop resistance to chemicals.
The importance of using fungicides was demonstrated
in field experiments near Pullman Washington during
successive growing seasons from 2002 to 2012. They were
conducted to improve chemical control of stripe rust for
major commercially grown cultivar with various levels of
resistance. The findings of this study showed that fungicide
application reduced AUDPC (Area under Disease Progress
Curve) by more than 80% in both susceptible winter wheat
and susceptible spring wheat when compared to untreated
controls. The AUDPC reduction depends on the duration
and severity of disease. Tilt (Propiconazole) was used
throughout this study and became the standard fungicide to
control stripe rust during this period (Chen, 2014).
Triadimenfon (Bayleton) was largely used to control wheat
stripe rust in China (Wan et al., 2007). The timing of
spraying fungicides is crucial for an effective control of stripe
rust (Chen, 2005, 2007). Viljanen-Rollinson et al. (2006)
revealed that using fungicides early in the growing season
leads to a better disease control.
However, the use of fungicides adds high input costs to
wheat production, which is a burden for many growers,
especially in developing countries. It causes numerous
negative health and environmental issues. Furthermore,
repeated applications may result in the selection of fungicide
resistant strains of the pathogen (Chen, 2005).
Cultural methods
Cultural methods provide another strategy to partially
control wheat stripe rust. Using a series of cultural practices
significantly enhances the existing sources of resistance. As a
result, crop management in terms of a combination of crop
choice, timing of seeding and removing volunteer cereals
may provide effective control of stripe rust (Roelfs, 1992;
Wan et al., 2007).
Stripe rust requires green material to survive from one
season to next, it is known as “green bridge”. Removing
volunteer plants (the Green Bridge) that will support stripe
rust survival is an effective control measure for epidemics
that result from endogenous inoculum (Roelfs, 1992).
Planting a mixture of wheat varieties with different
Khanfri S et al / Not Sci Biol, 2018, 10(3):410-423
419
Table 1.Types of resistance to stripe rust based on various ways of separation with modifications (Chen, 2013)
Ways for separation
Growth stage
Types of resistance
All-stage (seedling) resistance
Definition
Resistance can be detected in the
seedling stage but remains effective
Durability
Usually not durable
throughout all growth stages.
Adult plant resistance
Plants with adult plant resistance are
susceptible in the seedling stage but
Usually durable
become resistant in late stage.
Degree of resistance
Complete resistance (immune)
Resistant plants do not show any
visible disease symptom or pathogen
Usually not durable
sign.
Incomplete (partial) resistance
Resistance is not complete, showing
various degree of reduction in
Usually durable
infection type and/or severity.
Sensitivity to pathogen infection
Hypersensitive resistance
Resistant plants show necrotic tissue
Often not durable
result from cell death.
Non hypersensitive response
Either completely resistant (immune)
or reduced severity, but susceptible
Depends
infection type (e.g. slow rusting).
Number of genes
Monogenic resistance
Resistance is controlled by a single
Usually not durable
gene.
Polygenic resistance
Resistance is controlled by several to
Usually durable
many genes.
Resistance is inherited qualitatively,
Inheritance
Qualitative resistance
showing distinct two classes in a
Usually not durable
segregating population from a cross
with a susceptible genotype.
Quantitative resistance
Resistance is inherited quantitatively,
showing continuous variation in a
Usually durable
segregating population.
Specificity
Race specific resistance
Resistance is effective against some
races, but not effective against other
Usually not durable
races.
Non race specific resistance
resistance backgrounds may significantly reduce disease
pressure and may also increase or stabilize wheat yield
(Wolfe, 1985). Mechanisms by which cultivar mixtures
suppress disease may include dilution of spore’s density
because of the greater distance between susceptible plants, a
physical barrier created by the resistant plants in the canopy
that interrupt spore movement and induced resistance
(Castro, 2001; Huang et al., 2012) are also convenient.
Challenge of stripe rust control
Climate change
Increased temperatures could affect the phenological
growth stages of wheat (Juroszek et al., 2013). For example,
temperatures more than 34 °C could reduce the grain filling
period of wheat and accelerate plant senescence (Asseng et
al., 2011). Increased leaf senescence indirectly affects
pathogens development especially biotrophic fungi such as
Resistance is effective against all races
Usually durable
Puccinia species. High temperatures also directly impede
diseases development (Juroszek et al., 2013). Results showed
that pathogens may adapt themselves to warmer
temperatures (Chakraborty et al., 2011).
Climate change, in terms of rising temperatures, and the
timing and increasing variability of rainfall, influences the
spread and severity of rust diseases. In wheat, the expression
of many genes for resistance to stripe rust is influenced by
temperature and/or plant developmental stage. Findings of
a weakening of stripe rust resistance and pathogen
adaptation due to temperature increases were well
documented in annual race surveys in the Eastern USA
(Markell et al., 2008). In contrast, some stripe rust resistance
genes, such as Yr18, are known to be temperature mediated
and become more effective at higher temperatures (AktarUz-Zaman et al., 2017). Therefore, in varieties with this
resistance gene, there may be an enhancement of the
Khanfri S et al / Not Sci Biol, 2018, 10(3):410-423
420
effectiveness of resistance in a warming climate. On the
other hand, Kaur et al. (2008) have predicted that the
importance of wheat stripe rust disease might be reduced in
the future in Punjab state of India due to climate change.
New pathotypes of Pst can adapt to increased
temperatures. In the Eastern USA Pst races, collected after
2000, have different virulence profiles than races collected
before this year. These new races pose an increased risk to
wheat crops as the results of latent period and spore
germination indicated that the new population was better
adapted to high temperature (Chen, 2005).
High epidemic potential
Many yellow rust epidemics (Sanders, 2018) were
reported in Central and West Asia and East and North
Africa. The 2009-2010 epidemic severely affected many
countries including Morocco, Turkey, Algeria, Syria,
Lebanon, Iraq and Uzbekistan. Syria and Lebanon were the
worst hit of this epidemic; Syria lost nearly half of its wheat
harvest. In 2014, the Central Research Institute for Field
Crops in Ankara and the Regional Cereal Rust Research
Center in Izmir confirmed the detection of a new Pst race in
Turkey. The newly detected strain was “Warrior” race
previously identified in the United Kingdom in 2011. Some
of Turkish commercial cultivars known to be resistant to
the previously characterized races of Pst were recorded as
fully susceptible to this new race. The warrior race was
much more widespread in the following year after its first
detection. It was already present in high frequencies in most
European countries and North Africa (Mert et al., 2016)
and it was confirmed in Morocco in 2013 and in Algeria in
2014 (RustTracker, 2011). This race was very dissimilar to
pre-2011 European races. It showed relatively higher genetic
diversity than other previous races(Hovmøller et al., 2016).
Conclusions
Wheat stripe rust continues to be a major worldwide
limiting factor of wheat production. Global losses were
estimated to be at 5.5 million tons per year. The evolution
of pathogen races becomes larger and faster; the emergence
of new races with high epidemic potentials and which can
adapt to warmer temperatures has expanded virulence
profiles. The new highly aggressive strains have defeated key
resistance genes such as Yr27, used in breeding of many
wheat cultivars across Asia and Africa, which led to the
epidemic in 2009-2010. Climate change is aggravating the
severity and frequency of today’s new wheat problems.
Warmer winters induce earlier stripe rust infection and
spread. Thus, the severity of the epidemics will increase
throughout all wheat growing regions. Growing resistant
cultivars is the major component of integrated control of
stripe rust. However, the “breakdown” of resistance
following the introduction of new genes for resistance is a
major problem. Successful deployment of resistant crop
varieties at larger scales and in different regions would,
however, require: a better understanding of pathogen
diversity; regional and international collaboration to
effectively address the disease through data sharing; a long
term effort to control new and existing challenges to stripe
rust through research and development of resistant varieties
to emerging strains.
Acknowledgements
The authors are grateful to the Phytopathology Unit,
Department of Plant Protection and Environment, Ecole
Nationale d’Agriculture de Meknès, for the financial
support of this work.
References
Acevedo E, Silva P, Silva H (2006). Growth and wheat physiology,
development. Laboratory of Soil-Plant-Water Relations. Faculty of
Agronomy and Forestry Sciences. University of Chile. Casilla, 1004.
Aktar-Uz-Zaman M, Tuhina-Khatun M, Hanafi MM, Sahebi M (2017).
Genetic analysis of rust resistance genes in global wheat cultivars: an
overview. Biotechnology & Biotechnological Equipment 31(3):431445.
Al-Khayri JM, Jain SM, Johnson DV (2016). Advances in plant breeding
strategies: Agronomic, Abiotic and Biotic Stress Traits, Springer.
Ali S, Gladieux P, Leconte M, Gautier A, Justesen AF, Hovmøller MS,
Enjalbert J, De Vallavieille-Pope C (2014). Origin, migration routes and
worldwide population genetic structure of the wheat yellow rust
pathogen Puccinia striiformis f. sp. tritici. PLoS Pathogens 10(1):
e1003903.
Ali S, Rodriguez-Algaba J, Thach T, Sørensen CK, Hansen JG, Lassen
P,Nazari K, Hodson DP, Justesen AF, Hovmøller MS (2017). Yellow
rust epidemics worldwide were caused by pathogen races from divergent
genetic lineages. Frontiers in Plant Science 8:1057.
Asseng S, Foster I, Turner NC (2011). The impact of temperature variability
on wheat yields. Global Change Biology 17(2):997-1012.
Baily J ( 2013). Molecular and host specificity studies in Puccinia striiformis in
Australia. Doctor of Philosophy, PhD Thesis, The University of
Sydney, Plant Breeding Institute, Narrabi .
Balaghi R, Jlibene M, Tychon B, Eerens H (2012). La prédiction
agrométéorologique des rendements céréaliers au Maroc
[Agrometeorological prediction of cereal yields in Morocco]. INRA,
Maroc.
Berlin A, Samils B, Andersson B (2017). Multiple genotypes within aecial
clusters in Puccinia graminis and Puccinia coronata: improved
understanding of the biology of cereal rust fungi. Fungal Biology and
Biotechnology 4(1):3.
Boshoff W, Pretorius Z, van Niekerk B (2003). Fungicide efficacy and the
impact of stripe rust on spring and winter wheat in South Africa. South
African Journal of Plant and Soil 20:11-17.
Boyd L (2005). Can Robigus defeat an old enemy?–Yellow rust of wheat.
The Journal of Agricultural Science 143(4):233-243.
Brar GS (2015). Population structure of Puccinia striiformis f. sp. tritici, the
cause of wheat stripe rust, in western Canada. Master of Science.,
University of Saskatchewan, Saskatoon.
Brown JK, Hovmøller MS (2002). Aerial dispersal of pathogens on the
global and continental scales and its impact on plant disease. Science
297(5581):537-541.
Bulli P, Zhang J, Chao S, Chen X, Pumphrey M (2016). Genetic
architecture of resistance to stripe rust in a global winter wheat
germplasm collection. G3 (Bethesda) 6(8):2237-2253.
Cartwright D, Russell G (1981). Development of Puccinia striiformis in a
Khanfri S et al / Not Sci Biol, 2018, 10(3):410-423
421
susceptible winter wheat variety. Transactions of the British Mycological
Society 76(2):197-204.
Castro A (2001). Cultivar mixtures. The Plant Health Instructor.
Chakraborty S, Newton AC (2011). Climate change, plant diseases and
food security: an overview. Plant Pathology 60(1):2-14.
Chen X (2005). Epidemiology and control of stripe rust [Puccinia striiformis
f. sp. tritici] on wheat. Canadian Journal of Plant Pathology 27(3):314337.
Chen X (2007). Challenges and solutions for stripe rust control in the
United States. Australian Journal of Agricultural Research 58(6):648655.
Chen X (2013). High-temperature adult-plant resistance, key for sustainable
control of stripe rust. American Journal of Plant Sciences 4(03):608.
Chen X (2014). Integration of cultivar resistance and fungicide application
for control of wheat stripe rust. Canadian Journal of Plant Pathology
36(3):311-326.
Confalonieri R, Francone C, Cappelli G, Stella T, Frasso N, Carpani M, M,
Bregaglio S, Acutis M, Tubiello F, Fernandes E (2013). A multiapproach software library for estimating crop suitability to environment.
Computers and Electronics in Agriculture 90:170-175.
Conner R, Kuzyk A (1988). Effectiveness of fungicides in controlling stripe
rust, leaf rust and black point in soft white spring wheat. Canadian
Journal of Plant Pathology 10:321-326.
Cox T (1997). Deepening the wheat gene pool. Journal of Crop Production
1(1):1-25.
Curtis B (2002). Wheat in the world. Bread wheat: Improvement and
production. No. CIS-3616. CIMMYT.
Curtis B, Rajaram S, Macpherson H (2002). FAO Plant Production and
Protection Series, No. 30. Bread Wheat: Improvement and Production.
No. CIS-3616. CIMMYT
Dixon J, Braun H, Crouch J (2009). Overview: transitioning wheat research
to serve the future needs of the developing world. Wheat Facts and
Futures 1-25.
El Mekki AA (2006). Cereals policies in Morocco.
Ellis JG, Lagudah ES, Spielmeyer W, Dodds PN (2014). The past, present
and future of breeding rust resistant wheat. Frontiers in Plant Science
5:641.
FAO (2017). Food and Agriculture Organization of united nations.
Retrieved 2018 March 31 from http:// www. fao.org/ giews/
countrybrief/country.jsp?code=MAR
FAO (2018). Food and Agriculture Organization. Retrieved 2018 March
31 from http://www.fao.org/worldfoodsituation/csdb/en/
FAOSTAT (2018). Agriculture Organization of the United Nations.
Statistical Database. Retrieved 28 February 2018 from.
http://faostat.fao.org
Feldman M, Levy AA (2012). Genome evolution due to
allopolyploidization in wheat. Genetics 192(3):763-774.
Feuillet C, Muehlbauer GJ (2009). Genetics and genomics of the Triticeae
(Vol. 7). Springer Science & Business Media.
Francisco XRdV, Parlevliet JE, Zambolim L (2001). Concepts in plant
disease resistance. Fitopatologia Brasileira 26:577-589.
Getie B (2015). Identification, genetic studies and molecular characterisation
of resistance to rust pathogens in wheat. Doctor in philosophy, the
university of Sydney, Plant Breeding Institute, Cobbitty, March 2015.
Gommes R, El Hairech T, Rosillon D, Balaghi R, Kanamaru H (2009).
Impact of climate change on agricultural yields in Morocco. Rome:
FAO. Retrieved 2014 22 April from ftp: //extftp.fao.org /SD/Reserved
/Agromet/
WB_FAO_morocco_CC_yield_impact/report/Goncharov NP,
Golovnina KA, Kondratenko EY (2009). Taxonomy and molecular
phylogeny of natural and artificial wheat species. Breeding Science
59(5):492-498.
Harlan JR, de Wet JM (1971). Toward a rational classification of cultivated
plants. Taxon 509-517.
Higgins VJ, Lu H, Xing T, Gelli A, Blumwald E (1998). The gene-for-gene
concept and beyond: Interactions and signals. Canadian Journal of Plant
Pathology 20(2):150-157.
Hovmoller MS, Sorensen CK, Walter S, Justesen AF (2011). Diversity of
Puccinia striiformis on cereals and grasses. Annual Review of
Phytopathology 49:197-217.
Hovmøller MS, Walter S, Bayles RA, Hubbard A, Flath K, Sommerfeldt N,
Thach T (2016). Replacement of the European wheat yellow rust
population by new races from the centre of diversity in the
near‐Himalayan region. Plant Pathology 65(3):402-411.
Huang C, Sun Z, Wang H, Luo Y, Ma Z (2012). Effects of wheat cultivar
mixtures on stripe rust: A meta-analysis on field trials. Crop Protection
33:52-58.
Hysing S-C (2007). Genetic resources for disease resistance breeding in
wheat. PhD thesis, Swedish University of Agricultural Sciences, ,
Alnarp,.
Jin Y, Szabo LJ, Carson M (2010). Century-old mystery of Puccinia
striiformis life history solved with the identification of Berberis as an
alternate host. Phytopathology 100(5):432-435.
Juroszek P, von Tiedemann A (2013). Climate change and potential future
risks through wheat diseases: a review. European Journal of Plant
Pathology 136(1):21-33.
Kaur S, Dhaliwal L, Kaur P (2008). Impact of climate change on wheat
disease scenario in Punjab. Journal of Research 45(3-4):161-170.
Knott D (2008). The genomics of stem rust resistance in wheat. Plant
Sciences Department, University of Saskatchewan, Saskatoon,
Saskatchewan, S7N 5A8, Canada.
Kumar S, Kumari J, Bansal R, Kuri B, Singh AK, Wankhede D, Akhtar
J,Khan Z (2015). Slow rusting-an effective way to achieve durable
resistance against leaf rust in wheat. Wheat Information Service 120:26.
Leff B, Ramankutty N, Foley JA (2004). Geographic distribution of major
crops across the world. Global Biogeochemical Cycles 18(1).
Line RF (2002). Stripe rust of wheat and barley in North America: a
retrospective historical review. Annual Review in Phytopathology
40:75-118.
Liu B, Chen X, Kang Z (2012). Gene sequences reveal heterokaryotic
variations and evolutionary mechanisms in Puccinia striiformis, the stripe
rust pathogen. Open Journal of Genomics 1(1).
Longin CFH, Reif JC (2014). Redesigning the exploitation of wheat genetic
resources. Trends in Plant Science 19(10):631-636.
Ma Q, Shang H (2009). Ultrastructure of stripe rust (Puccinia striiformis f. sp.
tritici) interacting with slow-rusting, highly resistant, and susceptible
Khanfri S et al / Not Sci Biol, 2018, 10(3):410-423
422
wheat cultivars. Journal of Plant Pathology 1:597-606.
Mallard S, Gaudet D, Aldeia A, Abelard C, Besnard A, Sourdille P, Dedryver
F (2005). Genetic analysis of durable resistance to yellow rust in bread
wheat. Theoretical and Applied Genetics 110(8):1401-1409.
Markell S, Milus E (2008). Emergence of a novel population of Puccinia
striiformis f. sp. tritici in eastern United States. Phytopathology
98(6):632-639.
McDonald BA, Linde C (2002). Pathogen population genetics,
evolutionary potential, and durable resistance. Annual Review of
Phytopathology 40(1):349-379.
McIntoshA R (2009). History and status of the wheat rusts. Paper presented
at the Proceedings of the 2009 Technical Workshop Borlaug Global
Rust Initiative, Cd. Obregon, Sonora, Mexico, March.
McIntosh R, Dubcovsky J, Rogers JW, Morris C, Appels R, Xia X (2010).
Catalogue of gene symbols for wheat: 2011 Supplement. Annual
Wheat Newsletter 57.
Mert Z, Nazari K, Karagöz E, Akan K, Öztürk İ, Tülek A (2016). First
incursion of the warrior race of wheat stripe rust (Puccinia striiformis f. sp.
tritici) to Turkey in 2014. Plant Diseases 100(2):528.
Moldenhauer J, Moerschbacher B, Van der Westhuizen A (2006).
Histological investigation of stripe rust (Puccinia striiformis f. sp. tritici)
development in resistant and susceptible wheat cultivars. Plant
Pathology 55(4):469-474.
Morgounov A, Yessimbekova M, Rsaliev S, Baboev S, Mumindjanov H,
Djunusova M (2004). High-yielding winter wheat varieties resistant to
yellow and leaf rust in Central Asia. Paper presented at the Proceedings
of the 11th International Cereal Rusts and Powdery Mildews
Conference.
Mrabet R (2000). Differential response of wheat to tillage management
systems in a semiarid area of Morocco. Field Crops Research 66(2):165174.
Peng JH, Sun DNevo E (2011). Domestication evolution, genetics and
genomics in wheat. Molecular Breeding 28(3):281.
Pratap A, Kumar J (2014). Alien gene transfer in crop plants, Volume 2:
Achievements and Impacts (Vol. 2), Springer Science & Business
Media.
Pretorius Z (2004). The impact of wheat stripe rust in South Africa. Paper
presented at the Proceedings of the 11th International Cereal Rusts and
Powdery Mildews Conference.
Rajaram S, Borlaug N, Van Ginkel M (2002). CIMMYT international
wheat breeding. Bread wheat improvement and production. FAO,
Rome 103-117.
Roelfs AP (1992). Rust diseases of wheat: concepts and methods of disease
management. Cimmyt.
RustTracker (2011). RustTracker.org. Retrieved 2018 April 15 from.
http://rusttracker.cimmyt.org/?page_id=9
Saari EE, Prescott J (1985). World distribution in relation to economic losses.
In: Diseases, Distribution, Epidemiology, and Control pp 259-298.
Sanders R (2018). Strategies to reduce the emerging wheat stripe rust disease.
Schwessinger B (2017). Fundamental wheat stripe rust research in the 21st
century. New Phytologist 213(4):1625-1631.
Sharma I (2012). Disease resistance in wheat. India, Cabi.
Sharma R, Nazari K, Amanov A, Ziyaev Z, Jalilov A (2016). Reduction of
winter wheat yield losses caused by stripe rust through fungicide
management. Journal of Phytopathology 164:671-677.
Shiferaw B, Prasanna BM, Hellin JBänziger M (2011). Crops that feed the
world 6. Past successes and future challenges to the role played by maize
in global food security. Food Security 3(3):307.
Siad SM, Gioia A, Hoogenboom G, Iacobellis V, Novelli A, Tarantino E,
Zdruli P (2017). Durum wheat cover analysis in the scope of policy and
market price changes: A case study in Southern Italy. Agriculture
7(2):12.
Singh R, Mahmoudpour A, Rajkumar M, Narayana R (2017). A review on
stripe rust of wheat, its spread, identification and management at field
level. Research on Crops 18(3):528-533.
Singh RP, William HM, Huerta-Espino JRosewarne G (2004). Wheat rust
in Asia: meeting the challenges with old and new technologies. Paper
presented at the proceedings of the 4th International Crop Science
Congress, Brisbane, Australia.
Solh M, Nazari K, Tadesse W, Wellings C (2012). The growing threat of
stripe rust worldwide. Paper presented at the Proceedings, Borlaug
Global Rust Initiative, 2012 Technical Workshop, September 1-4,
Beijing, China, Oral presentations.
Sørensen CK (2012). Infection biology and aggressiveness of Puccinia
striiformis on resistant and susceptible wheat. PhD Thesis University of
Aarhus., Denmark, Nordre Ringgade, Aarhus.
Surico G (2013). The concepts of plant pathogenicity, virulence/avirulence
and effector proteins by a teacher of plant pathology. Phytopathologia
Mediterranea 399-417.
Thach T, Ali S, de Vallavieille-Pope C, Justesen AF, Hovmøller MS (2016).
Worldwide population structure of the wheat rust fungus Puccinia
striiformis in the past. Fungal Genetics and Biology 87:1-8.
USDA (2014). United States Department of Agriculture. Retrieved 2018
March 23 from https: //www. fas. usda. Gov /data/worldagriculturalproduction.
USDA (2017). United States Department of Agriculture. Retrieved 2018
March 31 from
https: //gain. fas.usda .gov/ Recent%
20GAIN20Publications/Grain%20and%20Feed%20Annual_Rabat_
Morocco_4-14-2017.pdf
Van der Plank J (1969). Pathogenic races, host resistance, and an analysis of
pathogenicity. Netherlands Journal of Plant Pathology 75(1-2):45-52.
Viljanen-Rollinson S, Marroni M, Butler R (2006). Wheat stripe rust
control using fungicides in New Zealand. New Zealand Plant
Protection 59:155-159.
Wan A, Chen X, He Z (2007). Wheat stripe rust in China. Australian
Journal of Agricultural Research 58(6):605-619.
Wan A, Wang X, Kang Z, Chen X (2017). Variability of the stripe rust
pathogen. In: Stripe Rust, Springer pp 35-154.
Wan A, Zhao Z, Chen X, He Z, Jin S, Jia Q, Li G (2004). Wheat stripe rust
epidemic and virulence of Puccinia striiformis f. sp. tritici in China in
2002. Plant Disease 88(8):896-904.
Wang MN, Chen X (2013). First report of Oregon grape (Mahonia
aquifolium) as an alternate host for the wheat stripe rust pathogen
(Puccinia striiformis f. sp. tritici) under artificial inoculation. Plant Disease
97(6):839-839.
Waqar A, Khattak SH, Begum S, Rehman T, Shehzad A, Ajmal W, Ali
Khanfri S et al / Not Sci Biol, 2018, 10(3):410-423
423
GM (2018). Stripe rust: A review of the disease, Yr genes and its
molecular markers. Sarhad Journal of Agriculture 34(1).
Webb CA, Fellers JP (2006). Cereal rust fungi genomics and the pursuit of
virulence and avirulence factors. FEMS Microbiology Letters 264(1):17.
Wellings C (2011). Global status of stripe rust: a review of historical and
current threats. Euphytica 179(1):129-141.
Wellings C, Kandel K (2004). Pathogen dynamics associated with historic
stripe (yellow) rust epidemics in Australia in 2002 and 2003. Paper
presented at the Proceedings of the 11th international cereal rusts and
powdery mildews conference.
Wellings C, McIntosh R, Walker J (1987). Puccinia striiformis f. sp. tritici in
Eastern Australia possible means of entry and implications for plant
quarantine. Plant Pathology 36(3):239-241.
Wolfe M (1985). The current status and prospects of multiline cultivars and
variety mixtures for disease resistance. Annual Review of
Phytopathology 23(1):251-273.
Yadav MK, Aravindan S, Ngangkham U, Shubudhi H, Bag MK, Adak T,
Munda S, Samantaray S, Jena M (2017). Use of molecular markers in
identification and characterization of resistance to rice blast in India. PloS
One 12(4): e0176236.
Zheng W, Huang L, Huang J, Wang X, Chen X, Zhao J, Kang Z (2013).
High genome heterozygosity and endemic genetic recombination in the
wheat stripe rust fungus. Nature Communications 4:2673.