Antifungal activity of some plant extracts
against sugar beet damping-off caused by
Sclerotium rolfsii
Aly Soliman Derbalah, Yaser Hassan
Dewir & Abd El-Naser Badawy El-Sayed
Annals of Microbiology
ISSN 1590-4261
Volume 62
Number 3
Ann Microbiol (2012) 62:1021-1029
DOI 10.1007/s13213-011-0342-2
1 23
Your article is protected by copyright and all
rights are held exclusively by Springer-Verlag
and the University of Milan. This e-offprint is
for personal use only and shall not be selfarchived in electronic repositories. If you
wish to self-archive your work, please use the
accepted author’s version for posting to your
own website or your institution’s repository.
You may further deposit the accepted author’s
version on a funder’s repository at a funder’s
request, provided it is not made publicly
available until 12 months after publication.
1 23
Author's personal copy
Ann Microbiol (2012) 62:1021–1029
DOI 10.1007/s13213-011-0342-2
ORIGINAL ARTICLE
Antifungal activity of some plant extracts against sugar beet
damping-off caused by Sclerotium rolfsii
Aly Soliman Derbalah & Yaser Hassan Dewir &
Abd El-Naser Badawy El-Sayed
Received: 18 March 2011 / Accepted: 2 August 2011 / Published online: 2 September 2011
# Springer-Verlag and the University of Milan 2011
Abstract In an attempt to search for natural pesticides,
crude extracts of seven plant species (Bauhinia purpurea,
Caesalpinia gilliesii, Cassia fistula, Cassia senna, Chrysanthemum frutescens, Euonymus japonicus and Thespesia
populnea var. acutiloba) were evaluated against Sclerotium
rolfsii, the causative fungus of damping-off, under laboratory and greenhouse conditions. Gas chromatography-mass
spectrometry analysis was performed to identify possible
biologically active components (tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, phytol, linalool, 1,8
cineole and 9, 12, 15 octadecanoic acid) from the plant
extracts most effective against S. rolfsii. Laboratory experiments indicated that leaf extracts of T. populnea var.
acutiloba and Chrysanthemum frutescens were most effective against S. rolfsii. Greenhouse experiments confirmed
that T. populnea var. acutiloba and Chrysanthemum
frutescens extracts were most effective against the
damping-off pathogen, either by coating or soaking of
sugar beet seeds. None of the extracts tested produced
phytotoxic effects on sugar beet leaves, even at the highest
concentration applied. The most effective plant extracts
showed low toxicity in rats relative to controls with respect
A. S. Derbalah (*)
Pesticides Department, Faculty of Agriculture,
Kafr El-Sheikh University,
33516, Kafr El-Sheikh, Egypt
e-mail: aliderbalah@yahoo.com
Y. H. Dewir
Horticulture Department, Faculty of Agriculture,
Kafrelsheikh University,
Kafr El-Sheikh 33516, Egypt
A. E.-N. B. El-Sayed
Plant Pathology Research Institute, Agriculture Research Center,
Giza, Egypt
to histological tests. The extracts assayed represent a
potentially safe control method for damping-off disease in
sugar beet.
Keywords Analysis . Extract . Pathogen . Sugar beet
Introduction
Sugar beet (Beta vulgaris L., Chenopodiaceae) is one of the
most important crops grown in temperate regions for sugar
production. In Egypt, it is ranked as the second crop after
sugar cane for sugar production (Eweis et al. 2006). Due to
the daily demand for sugar, there is a need to increase the
production of the sugar beet crop. Sugar beet is attacked by
several pathogens and root-rot diseases, among which are
those caused by Rhizoctonia solani and S. rolfsii (El-Abyad
et al. 1997).
Scleritium rolfsii is a soil-borne fungus that causes
damping-off disease on a wide range of agricultural and
horticultural crops, as well as weeds and forest trees. The
fungus is distributed in tropical and subtropical regions. It
is quite common in the Southern United States, as well as
central and South America. It has also been reported in
Africa, Asia, Australia and parts of Europe (Aycock 1966).
S. rolfsii is considered the most frequent, common and
serious pathogen that attacks sugar beet roots, causing
economic losses in the crop (Gouda 2001; Cramer et al.
2003). The pathogen is difficult to control because of the
production of hardy resistant survival structures called
sclerotia (Elad 1995). S. rolfsii is thought to have caused
serious crop losses over many centuries (Punja 1985).
The control of plant diseases has for many years been
based on the application of chemical pesticides. However,
these pesticides are not effective for long-term use due to
Author's personal copy
1022
concerns of expense, exposure risks, residues and other
health and environmental hazards. Moreover, the potential
for the development of resistance towards synthetic
fungicides in pathogenic fungi is of great concern.
Therefore, there is a great incentive to develop alternative
safe, effective, and environmentally friendly fungicides
(Mdee et al. 2009). Recent efforts have focused on the
development of long-lasting and environmentally safe
methods for the control of plant diseases. The use of plant
products has been shown to be eco-friendly and effective
against many plant pathogens (Latha et al. 2009). Presently,
a renewed search for natural products with novel uses,
particularly for pest management, is required. Most of these
substances have been tested against pests in order to
establish new control practices with low mammalian
toxicity and low persistence in the environment. Therefore,
research should focus not only on the efficacy of botanical
extracts against target pests, but also their safety with regard
to human health. An assessment of enzymatic activity in the
blood is generally a more sensitive measure of a compound’s toxicity than assessment of histopathological
changes; the latter can be assessed within a shorter time
period but may be less sensitive. Nevertheless, observation
of tissue alterations is considered to have a confirmatory
and supporting diagnostic role for detecting certain blood
abnormalities, and so may have potential relevance as a
preliminary test for the toxicity of botanical extracts
(Cornelius et al. 1959). Most of the selected extracts in
this study were confirmed by their natural origin and safety
as human medicines (Park et al. 2005; Panda and Kar
1999). Moreover, no evidence of teratogenic or genotoxic
activity has been detected resulting from the use of these
plant extracts for pest control (Mengs et al. 2004; Mitchell
et al. 2006). This is despite the fact that these plants are
available in high amount in Egypt.
The objectives of the present study were to investigate
the efficacy of newly used plant extracts on the growth
activities of S. rolfsii under laboratory and greenhouse
conditions. Other objectives were to identify by gas
chromatography-mass spectrometry (GC-MS) analysis the
biologically active compounds of the most effective plant
extracts, and finally to evaluate the toxicity of the most
effective plant extracts on rats using histology tests.
Materials and methods
Source of assay materials
The leaves of seven medicinal plant species (Bauhinia
purpurea, Caesalpinia gilliesii, Cassia fistula, Cassia
senna, Chrysanthemum frutescens, Euonymus japonicus
and Thespesia populnea var. acutiloba) were collected from
Ann Microbiol (2012) 62:1021–1029
local nurseries in Kafr El-Sheikh, Monofia, Gharbia and
Alexandria Governorates, Egypt. The leaves were ovendried for 24 h at 70°C, and finely powdered using a blender.
Each sample (25 g) was extracted twice with 300 ml
methanol at room temperature for 2 days. The extracts were
filtered through filter paper (no. 15, Whatman, Piscataway,
NJ) and the combined filtrates from the twice-extracted
leaves were concentrated to dryness by rotary evaporation
at 40°C. The yield of each methanolic extract is given in
Table 1.
The S. rolfsii isolate was obtained as a culture slant from
the Plant Pathology Research Institute, Giza, Egypt. Glass
bottles of 500 ml capacity, containing 100 g barley grains
and 100 ml water, were autoclaved for 30 min at 1.5 atm,
then inoculated with 7-day-old fungal culture and incubated
at 28±1°C for 15 days. The culture in the glass bottles was
used to inoculate soil in greenhouse experiments.
Synthetic fungicide
The synthetic fungicide tested in this study was thiram
37.5%+carboxin 37.5% and 25% Proprietary surfactants
with a trade name of vitavax 75% WP, produced by KafrEl-Zayat Co. (Kafr-El-Zayat, Egypt). This fungicide was
applied at its recommended field rate of 2 g/kg seeds. In
Egypt, this fungicide is highly recommended for the control
of damping-off disease in sugar beet.
Screening of plant extracts against S. rolfsii
under laboratory conditions
The seven extracts and thiram+carobxin were tested for
their efficacy against S. rolfsii in a completely randomized
design. The efficacy of the plant extracts and fungicide was
determined as percent of inhibition of the growth of the
selected fungus relative to the control treatment. Four
concentrations for each plant extract (50, 100, 150 and
200 ppm) and four concentrations for the fungicide (1, 10,
25 and 50 ppm) were used. The required concentrations for
plant extracts and fungicide were obtained by adding the
appropriate amount of stock solution used to 60 ml portions
of auto-calved potato dextrose agar (PDA) cooled to about
45°C. Four 9-cm-diameter glass Petri dishes were used as a
replicate for each concentration of each treatment, including
controls. Control treatment was carried out without adding
fungicide or plant extracts. Each dish was inoculated in the
center with a disk (5-mm diameter) bearing the mycelial
growth from 5-day-old cultures of S. rolfsii. The dishes
were sealed with Parafilm to avoid evaporation of
volatile compounds. The dishes were incubated at 28°C
until the controls achieved full growth, with mycelium
reaching the edge of the plates. The inhibition percentage
of radial growth of S. rolfsii was calculated using the
Author's personal copy
Ann Microbiol (2012) 62:1021–1029
Table 1 List of plant species
used for methanolic extraction
and their yield
a
(Dry weight of methanol
extract/dry weight of test
leaves)×100
1023
Family name
Scientific name
English name
Yield (%)a
Fabaceae
Fabaceae
Malvaceae
Asteraceae
Celastraceae
Fabaceae
Fabaceae
Cassia senna
Caesalpinia gilliesii
Thespesia populnea var. acutiloba
Chrysanthemum frutescens
Euonymus japonicus
Bauhinia purpurea
Cassia fistula
Senna plant
Bird of paradise
Wild tulip-tree
Marguerite daisy
Winged spindle
Purple camel's foot
Golden shower tree
10.4
10.6
8.4
15.2
11.2
13.3
17.3
formula suggested by Vincent (1947). Each experiment
(all concentrations for each treatment) was repeated three
times. The inhibition percentage was calculated as shown
in Eq. 1
% CDI ¼ A
B=A 100
ð1Þ
Where A=in controls and B=the radial growth of treated
fungal cultures; and B=the radial growth of the tested
fungus in treatment.
Efficacy of plant extracts against S. rolfsii in sugar beet
under greenhouse conditions
Seeds of sugar beet (Kawemira variety) were treated with
plant extracts by two methods with the most effective
concentration of each plant extract under laboratory conditions (200 ppm). In the first method, the crude extracts
were diluted in water to the most effective concentration
under laboratory conditions (200 ppm) for each extract, and
separate seed lots were soaked in this concentration for 8 h.
In the second method, seeds were moistened with the
required concentration of aqueous plant extracts. Then, talc
powder and few drops of gum were added to assist in
coating the seeds, which were subsequently air-dried.
At the greenhouse of Sakha Research Station in
Kafrelsheikh, Agriculture Research Centre, Cairo, Egypt,
the seeds were sown in sterilized 35-cm-diameter pots filled
with sandy clay soil previously sterilized with 5% formalin.
Each pot was filled with 5 kg soil and the soil infested with
the tested fungus at a rate of 2% fungus to soil (w/w). The
soil was then moistened with water for 1 week before seed
treatment and sowing. Sugar beet seeds were soaked or
coated in the tested plant extracts at the most effective
concentration under laboratory conditions (200 ppm), and
then 15 seeds were sown in each pot. The synthetic
fungicide (thiram+carboxin) was incorporated in a seed
coating using the talcum method or as a seed treatment by
soaking at a rate of 2 g/kg seeds as a reference compound
for this disease control. Plant growth was recorded after 15
and 45 days. The percentage of plants affected by dampingoff was also estimated according to the scale adopted by
Grainger (1949). Seeds soaked only in distilled water
served as controls for the soaking application. Sugar beet
seeds that were moistened with water and a few drops of
Arabic gum were used as a control for the coating
treatment. Survival percentages (efficacy of each treatment
relative to un-infected control) after 15 days (evaluation of
pre-emergence stage) and 45 days (evaluation of postemergence stage) of treatment were calculated as shown in
Eq. 2.
% Survival ¼ NOUP=TPN 100
ð2Þ
Where NOUPis thenumber of un-infected plants, and
TPN is the total plant number
Chemical composition of the most effective plant extracts
GC-MS analysis was performed to identify the components
of the most effective plant extracts (T. populnea var.
acutiloba and Chrysanthemum frutescens) according to
the method described by Duarte-Almeida et al. (2004). The
analysis was conducted on an HP 6890 GC system coupled
with a 5973 network mass selective detector with an HP5MS capillary column (60 m×0.25 mm, film thickness
0.25 μm). The oven temperature program was initiated at
50°C, held for 2 min and subsequently raised to 200°C at a
rate of 5°C min−1. Helium was used as the carrier gas at a
flow rate of 1.0 ml min−1, with a split ratio equal to 1/50.
The injector and detector temperatures were 250 and 200°
C, respectively. Some of the detected compounds in the
tested plant extracts were identified by comparison of their
retention indices (RI) and mass spectra fragmentation with
the available analytical standards: tetradecanoic acid,
pentadecanoic acid, hexadecanoic acid, octadecanoic acid,
linalool, 1,8-cineole and 9,12,15-octadecanoic acid. They
were also identified by comparison of their RI and mass
spectra fragmentation with those stored in the Wiley and
NIST libraries associated with GC-MS. Several other
compounds could be identified only through the second
method. The samples were analyzed by the Central
Laboratory for Pesticides, Agriculture Research Centre,
Cairo, Egypt.
Author's personal copy
1024
Ann Microbiol (2012) 62:1021–1029
Toxicity assessment
Table 2 Efficacy of plant extracts against damping-off of sugar beet
caused by Sclerotium rolfsii under laboratory conditions
Toxicity assessments were performed using 8-week-old 80–
100 g Wistar male rats (Rattus norvegicus) obtained from
the Faculty of Medicine, Tanta University, Egypt. Wister
rats were housed in wire cages under standard conditions
with free access to drinking water and food. The rats were
kept in a temperature-controlled room with 14 h light and
10 h dark cycles. The rats were given a standard diet as
described by Romestaing et al. (2007). Before treatment,
the rats were maintained normally for 2 weeks during
feeding for adaptation. The rats were divided randomly into
three groups, each comprising three animals. Two groups
were subjected to the treatment with the most effective
plant extracts and the third group served as a control. The
most effective plant extracts (T. populnea var. acutiloba and
Chrysanthemum frutescens) were administered to rats
orally at a concentration of 500 mg/kg body weight.
Control group rats were orally administrated an equal
amount of almond oil. After 21 days of treatment, the rats
were sacrificed under anesthesia. Specimens from lung and
liver were taken from each treatment and kept in 10%
neutral buffered formalin for histopathological tests. The
histopathology tests were carried out at the Histopathology
Laboratory, Department of Histopathology, Faculty of
Veterinary Medicine, Kafr El-Sheikh University according
to the method described by Bancroft and Stevens (1996).
Treatment
Extract
concentration (ppm)
Inhibition
percentage (%)
Cassia senna
50
100
150
200
50
100
150
200
50
100
150
200
50
100
150
200
50
100
16.50
34.50
57.80
78.30
22.50
41.30
61.00
79.50
21.00
52.80
67.00
82.80
20.70
53.25
63.40
79.00
21.00
34.20
150
200
50
100
150
200
50
100
150
200
1
10
25
50
0.00
65.20 g
78.00 e
5.00 o
15.00 m
53.30 h
75.00 f
9.80 n
34.50 k
38.80 j
74.00 f
98.00 a
90.70 c
94.50 b
94.50 b
0.00 p
Caesalpinia gilliesii
Thespesia populnea
var. acutiloba
Chrysanthemum frutescens
Euonymus japonicus
Bauhinia purpurea
B. purpurea
Statistical analysis
Cassia fistula
Data were subjected to the analysis of variance test and
Newman-Keuls’s multiple range test using a computer
program SAS (Version 6.12, SAS Institute, Cary, NC).
Thiram+Carboxin
Results
Efficacy of the tested plant extracts against S. rolfsii
under laboratory conditions
The leaf extracts inhibited the radial growth of S. rolfsii
significantly compared to the control. The leaf extract of
T. populnea var. acutiloba was the most effective against
S. rolfsii, with an inhibition percentage of 82.8%,
followed by Chrysanthemum frutescens, Caesalpinia gilliesii,
E. japonicus, Cassia senna, B. purpurea and Cassia fistula
with inhibition percentages of 79.5, 78.3, 78.0, 77.2, 75.0
and 74.0%, respectively (Table 2). However, the standard
fungicidal treatment against S. rolfsii (thiram+carboxin) was
still the most effective treatment compared to all plant
extracts. The efficacy of the tested plant extracts was dosedependent, since the toxicity against S. rolfsii increased as
their concentration increased.
Control
m*
k
gh
e
kl
i
g
de
l
h
fg
d
l
h
g
de
l
k
*Lower case letters in this column indicate separation of means
according to the Student Newman Keuls multiple range test (P<0.05)
Efficacy of the tested plant extracts against S. rolfsii
under greenhouse conditions
Table 3 and Figs. 1 and 2 show the relative efficacy of the
plant extracts and the synthetic fungicide against S. rolfsii
under greenhouse conditions. Among seed-soaking treatments, thiram+carboxin was the most effective treatment
against S. rolfsii , followed by T. populnea var. acutiloba,
Chrysanthemum frutescens, Caesalpinia gilliesii, Cassia
senna, E. japonicus, Cassia fistula and B. purpurea
extracts. The survival percentages of sugar beet plants after
Author's personal copy
Ann Microbiol (2012) 62:1021–1029
1025
Table 3 Efficacy of plant extracts (200 ppm) against S. rolfsii by either soaking or coating sugar beet seeds relative to thiram+carboxin (2 g/kg)
under greenhouse conditions
Treatment
No. seedling survival
Coating treatment
Soaking treatment
Pre-emergence 15 days
Post emergence 45 days
Pre-emergence 15 days
Post emergence 45 days
Cassia senna
Caesalpinia gilliesii
Thespesia populnea var. acutiloba
Chrysanthemum frutescens
Euonymus japonicus
Bauhinia purpurea
Cassia fistula
25.0
27.9
30.1
33.1
25.8
21.5
22.7
21.9
24.5
28.6
28.8
21.6
19.1
20.0
e
d
c
c
e
g
f
20.5 f
25.5 d
28.45c
28.8 c
23.4 e
20.4 f
20.4 f
17.7
21.6
25.4
24.4
21.1
19.1
16.0
Thiram+carboxin
Control (infected)
Control (non-infected)
35.9 b
9.9 h
44.6 a
31.1 b
9.0 h
40.5 a
31.8 b
7.6 g
38.5 a
28.1 b
5.1 g
31.4 a
f*
e
d
c
f
g
g
ef
d
c
c
d
e
f
*Lower case letters in this column indicate separation of means according to the Student Newman Keuls multiple range test (P<0.05)
mum frutescens, Caesalpinia gilliesii, Cassia senna and
Cassia fistula extracts against S. rolfsii was higher when the
sugar beet seeds were soaked rather than coated. However,
the remaining four plant extracts and the synthetic
fungicide each had lower efficacy when sugar beet seeds
were soaked rather than coated. There was no observed
phytotoxicity of the plant extracts on the sugar beet
seedlings.
treatment were 68.2, 64.1, 63.9, 58.9, 48.4, 48.2, 44.5 and
42.9% for the above mentioned treatments, respectively
(Fig. 1).
Thiram+carboxin was the most effective seed-coating
treatment against S. rolfsii, followed by T. populnea var.
acutiloba, Chrysanthemum frutescens, Caesalpinia gilliesii,
E. japonicus, Cassia senna, B. purpurea and Cassia fistula
extracts, respectively. The survival of sugar beet plants after
treatment was 71.0, 64.2, 60.9, 5, 53.4, 48.8, 44.3 and 38.9
%, respectively, for the above-mentioned treatments
(Fig. 2).
Moreover, the respective efficacy of plant extracts versus
the synthetic pesticide was, in both cases, lower than
efficacy after 45 days for both methods of seed treatment
(Table 3; Figs. 1, 2). Generally, the efficacy of Chrysanthe-
The compounds identified in the most effective botanical
extracts (T. populnea var. acutiloba and Chrysanthemum
frutescens) against S. rolfsii are illustrated in Tables 4 and 5.
A total of 25 compounds were identified from T. populnea
90
80
70
60
50
40
30
pu
po
a
si
pe
es
Th
n
xi
ar
C
+
m
ira
Th
ea
ln
em
th
an
ys
hr
C
bo
ob
til
cu
r.
a
va
fru
um
lp
sa
ae
C
Treatments
a
s
en
sc
te
gi
ia
in
ja
us
ym
on
Eu
si
llie
cu
ni
po
rp
pu
ia
in
uh
Ba
i
s
ea
ur
nn
si
as
C
C
as
si
a
a
se
fis
on
tu
tro
l
la
a
20
10
0
C
Survival %
Fig. 1 Survival percentages
[mean±standard error (SE)] of
sugar beet plants infested with
Sclerotium rolfsii subsequent to
various seed-soaking treatments
after 45 days under greenhouse
conditions
Composition of the most effective plant extracts
Author's personal copy
1026
Ann Microbiol (2012) 62:1021–1029
Fig. 2 Survival percentages
(mean± SE) of sugar beet plants
surviving infestation with S.
rolfsii subsequent to various
seed-coating treatments after
45 days under greenhouse
conditions
80
70
Survival %
60
50
40
30
20
10
Ba
uh
i
C
on
tro
ni
l
a
pu
rp
ur
ea
C
as
si
Eu
a
on
fis
ym
tu
la
us
ja
po
ni
cu
C
s
as
si
a
C
ae
se
C
nn
sa
hr
l
a
y
pi
sa
Th
n
ia
nt
es
he
gi
pe
llie
m
si
u
si
a
m
i
po
fru
pu
te
ln
sc
ea
en
va
s
r.
ac
ut
Th
ilo
ria
ba
m
+C
ar
bo
xi
n
0
Treatments
var. acutiloba extract, while 12 compounds were identified
from Chrysanthemum frutescens extract (Tables 4, 5). The
identified compounds included aldehydes, esters, alcohols
and fatty acids.
Table 4 The main constituents
of Thespesia populnea var.
acutiloba extract determined
by gas chromatography-mass
spectroscopy (GC-MS) analysis
Toxicity evaluation
The normal structure of rat lung tissue is shown in Fig. 3a.
For rats treated with T. populnea var. acutiloba extract at
No.
Compound
Retention time (min)
Area (%)
1
2
3
4
5
6
7
8
9
10
11
12
Cyclohexanone (dimethyl acetal)
Methoxy propoxy 2-propanol
Cyclohexasiloxane
1,6,10-Dodecatriene,7,11-methyl-3-methylene
Cycloheptasiloxane (tetradecamethyl)
Diethyl phthalate
Benzene,(1-butylheptyl)
Benzene,(1-methyldecyl)
Tetradecanoic methyl ester
2,6,10-Dodecatrien-1-ol,3,7,11-trimethyl
Benzene,(1-butyloctyl)
Tetradecanoic acid
5.02
5.19
7.96
9.24
9.47
10.51
10.72
11.32
11.43
11.52
11.57
11.91
16.81
8.51
0.94
0.25
2.2
0.53
0.57
0.18
0.38
0.79
0.36
1.09
13
14
15
16
17
18
19
20
21
22
23
24
25
Cyclononasiloxane
Isopropyl myristate
Neophytodiene
Loliolide
Pentadecanoic acid
N-hexadecanoic
9,12,15-Octadecanoic-methyl-ester
Phytol
9,12,15-Octadecatrien-1-ol
9,12,15-Octadecanoic acid
Octadecanoic acid
Di-n-octyl phthalate
Vitamin E
12.26
12.36
12.51
12.59
13.41
14.19
15.56
15.74
16.38
16.42
16.6
21.69
29.84
1.78
0.61
2.51
0.93
1.91
14.54
3.15
5.02
11.97
3.72
3.09
3.77
0.51
Author's personal copy
Ann Microbiol (2012) 62:1021–1029
1027
Table 5 Main constituents of Chrysanthemum frutescens extract
determined by GC-MS analysis
No.
Compound
Retention
time (min)
Area
(%)
1
2
3
4
5
6
1,8-Cineole
Linalool
Cyclohexasiloxane (dodecamethyl)
Terpinyl acetate
2,6-Octadien-1-ol3,7dimethyl
1,6,10-Dodecatriene,7,11-methyl3-methylene
Cycloheptasiloxane (tetradecamethyl)
Cyclononasiloxane (octadecamethyl)
Cyclohexadecane
1,9-Tetradecadiene
Iron monocarbonyl −1,3 butadiene
1,4 dicarbonic acid diethyl ester
a,a dipyridyl
Tetradecanoic acid octadecyl ester
4.98
5.70
4.74
8.14
8.38
9.02
13.33
8.18
1.34
21.6
1.44
3.83
3.25
11.97
12.65
14.6
26.75
3.68
2.86
2.48
4.34
3.27
27.08
6.13
7
8
9
10
11
12
dose of 500 mg/kg, the tissue was somewhat similar to
control samples and displayed a small amount of infiltration
by lymphocytes and an increase in cell mass (Fig. 3b). For
rats treated with Chrysanthemum frutescens extract at the
same dose level, the lung was observed to be as normal as
the control with some diffusion of blood and mild
thickening (Fig. 3c).
The normal structure of liver tissue is shown in Fig. 4a.
In rats treated with T. populnea var. acutiloba at dose of
500 mg/kg, blood vessels appeared to be engorged with
blood and hepatocytes contained vacuolated cytoplasm
(Fig. 4b). However, treated livers looked similar to controls.
In the case of rats treated with Chrysanthemum frutescens
at the same dose level, livers were obsesrved to appear as
normal as controls. There were blood vessels engorged with
blood and activation of Kopffer cells. A few instances of
lymphatic infiltration and blood vessels engorged with
blood were observed (Fig. 4c).
Discussion
Many plant extracts have been reported to have efficacy
against S. rolfsii under either laboratory or greenhouse
conditions (El-Shoraky 1998; Yossry et al. 1998; Elshahawy 2002; Eltoony 2003; Okemo et al. 2003).
However, for the plant extracts assayed in this study, this
is the first report of their efficacy against S. rolfsii.
It was observed that, among the compounds identified from
extracts of Chrysanthemum frutescens and T. populnea var.
A
A
B
B
C
C
Fig. 3a–c Sections from rat lungs, 21 days after treatment with plant
extracts at a dose level of 500 mg/kg. a Control, bThespesia populnea
var. acutiloba, c Chrysanthemum frutescens
Fig. 4a–c Sections from rat livers, 21 days after treatment with plant
extracts at a dose level of 500 mg/kg. a Control, bThespesia populnea
var. acutiloba, c Chrysanthemum frutescens
Author's personal copy
1028
acutiloba, constituents such as tetradecanoic acid; tetradecanoic acid; pentadecanoic acid; N-hexadecanoic acid; hexadecanoic acid; phytol; linalool; 1,8 cineole and 9, 12, 15
octadecanoic acid were detected with high percentages
relative to other detected compounds. The antifungal activity
of Chrysanthemum frutescens and T. populnea var. acutiloba
extracts against S. rolfsii may be due to the presence of these
fatty acids and their derivatives (Hammer et al. 2003; Walters
et al. 2004; Wagh et al. 2007; Tzakou et al. 2001; Cheraif et
al. 2007; Chutia et al. 2009; Kelen and Tepe 2008; Soković
et al. 2009; Ahmadi et al. 2010). Moreover, the efficacy of
the most effective plant extracts at higher concentrations
might actually be comparable to chemical pesticides. In fact,
the actual dosage of any one compound identified in these
extracts could be relatively low, safe, and economically
feasible.
Although the antimicrobial activity of plant extracts is
attributed mainly to their major components, the synergistic
or antagonistic effect of minor components such as loliolide
(0.93%) has to be considered because they have known
antifungal activity (Ragas et al. 2002). Therefore, each
component of the plant extract may potentially make a
unique contribution to their activity.
Under greenhouse conditions, it was observed that the
efficacy of Chrysanthemum frutescens extract against S.
rolfsii was slightly higher than extracts of T. populnea var.
acutiloba. This may be due to the presence of known
bioactive compounds such as 1,8 cineole (33.33%), linalool
(8.18%) and terpinyl acetate (21.6%), with higher percentages occurring in the extract of Chrysanthemum frutescens
versus T. populnea var. acutiloba (Tables 4, 5).
Botanical extracts as pest control agents present two
main characteristics: the first is their safety to humans and
the environment, and the second is a lower likelihood of
resistance developing within the pathogen of concern.
Regarding safety, the toxicity evaluation of most effective
plant extracts revealed that there were some slight variations that occurred sporadically in treated rats relative to
control with respect to the histopathology of treated organs.
Moreover, the observed changes in tissues were mostly
uncorrelated with dosage, which potentially indicates the
safety of these plant extracts in the context of human health.
Also, the rat tests are often more sensitive and may not
reflect human sensitivity. Moreover, the exposure levels
may be far greater than what would actually be experienced
or detected in sugar beet crops after they are grown and
processed.
The use of essential oils in antimicrobial agents is
considered to present relatively low risk where the
development of resistance in pathogenic organisms is
concerned. Concerning resistance development, it is believed that it is difficult for the pathogen to develop
resistance to such a mixture of bioactive components with
Ann Microbiol (2012) 62:1021–1029
apparently different mechanisms of antimicrobial activity
(Liu et al. 2008).
This study implies the effectiveness of the tested plant
extracts as an alternative to synthetic fungicides for
controlling a major damping-off pathogen of sugar beet.
The use of control measures based on these extracts has the
potential to reduce environmental pollution and the adverse
effects on human health that are a risk where synthetic
pesticides are used.
Conclusions
The tested plant extracts can be considered a natural source
of fungicidal material potentially useful for the control of S.
rolfsii in sugar-beet crop. Antifungal activity was confirmed
in all of the assayed plant species, despite some variation in
their efficacy against damping-off. In vivo results under
greenhouse conditions confirmed that these plant extracts
can be used as a viable and safe alternative for controlling
S. rolfsii. Further research on the practical effectiveness of
non-phytotoxic plant extracts or essential oils for plant
protection is needed.
References
Ahmadi F, Sadeghi S, Modarresi M, Abiri R, Mikaeli A (2010)
Chemical composition, in vitro anti-microbial, antifungal and
antioxidant activities of the essential oil and methanolic extract of
Hymenocrater longiflorus Benth of Iran. Food Chem Toxicol
48:1137–1144
Aycock R (1966) Stem rot and other diseases caused by Sclerotium
rolfsii. N C Agric Exp Stn Tech Bull 174:202
Bancroft JD, Stevens A (1996) Theory and practice of histopathological techniques, 4th edn. Churchill Livingstone, New York, NY
Cheraif I, Ben Jannet H, Hammami M, Khouja ML, Mighri Z (2007)
Chemical composition and antimicrobial activity of essential oils
of Cupressus arizonica Greene. Biochem Syst Ecol 35:813–820
Chutia M, Bhuyan PD, Pathak MG, Sarma TCP, Boruah P (2009)
Antifungal activity and chemical composition of Citrus reticulata
Blanco essential oil against phytopathogens from North East
India. LWT Food Sci Technol 42:777–780
Cramer RA, Byrne PF, Brick MA, Panella L, Wickliffe E, Shchwartz
HF (2003) Characterization of Fusarium oxysporum isolates
from common bean and sugar beet using pathogenecity assays
and random amplified polymeric DNA markers. J Phytopathol
151:352–360
Cornelius CE, Bishop J, Switzer J, Rhode EA (1959) Serum and tissue
transaminase activities in domestic animals. Cornell Vet 49:116–121
Duarte-Almeida JM, Negri G, Salatino A (2004) Volatile oils in
Leaves of Bauhina (Fabaceae Coesaplinioideae). Biochem Syst
Ecol 32:747–753
El-Abyad MS, Abu-taleb AM, Abdel-Mawgoud T (1997) Response of
host cultivar to cell wall-degrading enzymes of the sugarbeet
pathogens Rhizoctonia solani Kühn and Sclerotium rolfsii Sacc.
under salinity stress. Microbiol Res 152:9–17
Elad Y (1995) Mycoparasitism. In: Kohmoto K, Singh US, Singh RP
(eds) Pathogenesis and host specificity in plant diseases:
Author's personal copy
Ann Microbiol (2012) 62:1021–1029
histopathological, biochemical, genetic and molecular bases, vol
II, eukaryotes. Pergamon, Oxford, pp 285–307
El-Shoraky FSA (1998) Using extracts and oils of some plant
diseases. Tanta University, Egypt, Dissertation
Eltoony AME, Awad NGH, Tadrous MFE, Ahmed FS (2003) Chemical
and biological control of tomato damping-off disease under nursery
conditions with special references to the antagonism between the
causal pathogens. Egyptian J Appl Sci 18:47–68
El-shahawy EA (2002) Biocidal effect of some compounds on some
soil borne fungi. Tanta University, Egypt, Dissertation
Eweis M, Elkholy SS, Elsabee MZ (2006) Antifungal efficacy of
chitosan and its thiourea derivatives upon the growth of some
sugar-beet pathogens. Int J Biol Macromol 38:1–8
Gouda MI (2001) Studies on some casuals of sugar beets root rot.
Tanta Universty, Egypt, Dissertation
Grainger J (1949) Crop and diseases. Plant pathology Department,
West of Scotland Agriculture, College Research Bull 9:51
Hammer KA, Carson CF, Riley TV (2003) Antifungal activity of the
components of Melaleuca alternifolia (tea tree) oil. J Appl
Microbiol 95:853–860
Kelen M, Tepe B (2008) Chemical composition, antioxidant and
antimicrobial properties of the essential oils of three Salvia
species from Turkish flora. Bioresour Technol 99:4096–4104
Latha P, Anand T, Ragupathi N, Prakasam V, Samiyappan R (2009)
Antimicrobial activity of plant extracts and induction of systemic
resistance in tomato plants by mixtures of PGPR strains and
Zimmu leaf extract against Alternaria solani. Biol Control
50:85–93
Liu W-W, Mu W, Zhu B-Y, Du Y-C, Liu F (2008) Antagonistic
activities of volatiles from four strains of Bacillus spp. and
Paenibacillus spp. against soil-borne plant pathogens. Agric Sci
China 7:1104–1114
Mdee LK, Masoko P, Eloff JN (2009) The activity of extracts of seven
common invasive plant species on fungal phytopathogens. South
Afr J Bot 75:375–379
Mengs U, Mitchell J, McPherson S, Gregson R, Tigner J (2004) A 13week oral toxicity study of senna in the rat with an 8-week
recovery period. Arch Toxicol 78:269–275
1029
Mitchell JM, Mengs U, McPherson S, Zijlstra J, Dettmar P, Gregson
R, Tigner JC (2006) An oral carcinogenicity and toxicity study of
senna (Tinnevelly senna fruits) in the rat. Arch Toxicol 80:34–44
Okemo OP, Baisa HP, Jorge M, Vivancoa JM (2003) In vitro activities
of Maesa lanceolata extracts against fungal plant pathogens.
Fitoterapia 74:312–316
Panda S, Kar A (1999) Withania somnifera and Bauhinia purpurea in
the regulation of circulating thyroid hormone concentrations in
female mice. J Ethnopharmacol 67:233–239
Park SH, Ko SK, Chung SH (2005) Euonymus alatus prevents the
hyperglycemia and hyperlipidemia induced by high-fat diet in
ICR mice. J Ethnopharmacol 102:326–335
Punja ZK (1985) The biology, ecology, and control of Sclerotium
rolfsii. Annu Rev Phytopathol 23:97–127
Ragas CY, Hofilena JG, Rideout JA (2002) New furanoid diterpenes
from Caesalpinia pulcherrima. J Nat Prod 65:1107–1110
Romestaing C, Piquet M, Bedu E, Rouleau V, Dautresme M,
Hourmand-Ollivier I, Filippi C, Duchamp C, Sibille B (2007)
Long term highly saturated fat diet does not induce NASH in
Wistar rats. Nutr Metab 4:4. doi:10.1186/1743-7075-4-4
Soković MD, Vukojević J, Marin PD, Brkić DD, Vajs V, Griensven
LLD (2009) Chemical composition of essential oils of Thymus
and Mentha species and their antifungal activities. Molecules
14:238–249
Tzakou O, Pitarokili D, Chinou IB, Harvala C (2001) Composition
and antimicrobial activity of the essential oil of Salvia ringens.
Planta Med 67:81–83
Vincent JH (1947) Distortion of fungal hyphae in presence of certain
inhibitors. Nature 159:850–850
Yossry AA, Abedalal SM, El-Imery SM (1998) Fungi toxic properties
of some plant extracts against the growth of soil borne disease
fungi. Ann Agric Sci Moshtohor 3:891–909
Wagh P, Rai M, Deshmukh SK, Durate MCT (2007) Bioactivity of oils
of Trigonella foenum-graecum and Pongamia pinna. Afr J
Biotechnol 6:1592–1596
Walters D, Raynor L, Mitchell A, Walker R, Wallker K (2004)
Antifungal activity of four fatty acids against plant pathogenic
fungi. Mycopathology 157:87–90