Faba bean, Vicia faba L. is one of the major pulse crops grown in Egypt.
It is a multi-purpose crop that plays an important role in the socio-economic
life of farming communities (Agegnehu and Fessehaie, 2006).
Improvement of seed yield of faba bean via hybridization, mutation and selection
are being hampered by diseases. Since faba bean crop is cultivated in different
seasons with different genotypes, the crop may respond differently to economic
traits including diseases resistance (Torres et al.,
In general the production of faba bean, has been constrained by several biotic
and abiotic factors as riverward by EL-Bramawy and Abdul
Wahed (2005) and Agegnehu and Fessehaie (2006).
Diseases are among the most important biotic constraints limiting the production
of faba bean. A virus disease caused by Bean Yellow Mosaic Virus (BYMV) is one
of the economically important diseases that damages the foliage, limits photosynthetic
activity (depending on the infection stage) and reduces faba bean production
globally (Cheng et al., 2002; Miteva
et al., 2005). In the Arabic region loss due to BYMV disease can
be reached up to 30% on susceptible cultivars of faba bean (Khalil
and Erskine, 2001). In Egypt region, a specific Ismailia Governorates, whereas
working considering, the loss due to BYMV infection could be around 55.6 and
81.00% due to different environmental conditions and the wide distribution range
of insects in the Ismailia district (EL-Beshehy, 1999).
The disease can also cause total crop failure under severe epidemic conditions
(Cheng et al., 2002). Therefore, BYMV is a major
limiting factor in the main faba bean growing regions of Egypt. Therefore, using
of resistant cultivars is the most desirable control method, because it provides
a practical, long-term and environmentally benign means of limiting the damage
from this disease (Wang et al., 2001). Most studies
of resistance to diseases in faba bean crop have concentrated on fungal diseases
resistance but virus disease (BYMV) resistance is so few than others. Hence,
it is so necessary to search toward sources of the resistance to BYMV in faba
bean and knowing the mode of inheritance the resistance to virus disease (BYMV)
in faba bean crop.
From these studies, faba bean populations could be probably enough to evaluate
their resistance to BYMV under green house conditions to know the bearing/attitude
with this pathogen. For this reason, therefore, since a little work had been
done on faba bean virus diseases in Egypt, especially the inheritance of the
resistance to this disease (BYMV), the objective of this study was to determine
the inheritance of the resistance to BYMV in the crop populations (F1s,
F2s and F3s considered and their relation
with the biochemical changes which associated with virus incidence under artificial
infection conditions by BYMV.
MATERIALS AND METHODS
BYMV source: Samples of faba bean plants exhibiting venial yellowing,
followed by obvious green or yellow mosaic, vein banding with yellowish line
patterns were collected from eight different fields of Ismailia Governorate.
These samples were tested serologically against BYMV, using specific polyclonal
antibodies by direct ELISA test, according to the method described by Clark
and Adams (1977). Leaf samples which gave positive reaction with specific
BYMV antibodies, were extracted and diluted to be used for inoculation faba
bean cv. Giza 461 (Radwan et al., 2008).
Parental selected and background of genetic populations: Since few years
ago (2003 and 2004), a breeding program for disease resistance in faba bean
was started in the Agronomy Department, Faculty of Agriculture, Suez Canal University,
Ismailia, Egypt. EL-Bramawy and Abdul Wahed (2005).
This breeding program was started by using twenty faba bean genotypes which
were varied between domestic and introduced genotypes.
Some of these faba bean genotypes were tested in earlier with BYMV (Radwan
et al., 2008). According the previous studies for the potential high
yield and BYMV diseases resistance, we selected a six faba bean genotypes as
a parents materials using as a basic for breeding program via diallel cross
in the forma of half diallel cross of the six faba bean genotypes, two faba
bean plants (BPL 710 and Giza 3) were determined and considered as appeared
as a cornerstone of this research work. The first one (BPL 710) was resistance
to BYMV but the second one (Giza 3) was susceptible to BYMV.
Parental determination cross and obtaining generations: The genotypes
of the two faba bean plants (BPL 710 and Giza 3) were selfed three times, retested
in the field between each generation of selfing and the resulting S3
individuals used as resistant and susceptible faba bean parents. The resistant
(BPL 710) and susceptible (Giza 3) cultivars were crossed to create F1
hybrids (First generation). Then ten F1 individuals from two different
parental crosses were selfed to produce the F2 populations (Second
generation). Twenty-six resistant or susceptible F2 individuals,
from four different families, were selfed to produce F3 populations
(Third generation). These hybridizations for obtaining the three generations
(F1, F2 and F3), were carried out in the experimental
Farm, through three seasons (2005/06, 2006/07 and 2007/08), respectively.
Green house testing of the faba bean generatios resistance: F1,
F2 and F3 faba bean generations plants were tested at
the green house in 2008/09 and 2009/2010. Seeds of the faba bean generations
(F1, F2 and F3) were sown in pots (40 cm in
diameter) by rate of 10 seeds per pot. Experimental plants of the F1,
F2 and F3 were arranged in a completely randomized block
design with three replications to account for eventual differences in BYMV incidence
development. At planting the seedlings of every F1, F2
and F3 populations were split into three equal groups and each group
assigned to a different block. We tested 30 F1, 225 F2
and 315 F3 faba bean plants. Every generatios plant was evaluated
after three weeks of inoculation using the interaction faba bean phenotype with
Infection of BYMV inoculum on faba bean plants: The inoculum was prepared from BYMV infected top faba bean leaves, ground in a mortar containing 0.1 M phosphate buffer, pH 7.0 (1:2 w:v). The homogenate was filtrated through two layers of muslin and the leaves of healthy plants were dusted with carborundum and rubbed gently with a cotton swab previously dipped into the suspension of virus inoculums. The faba bean plants were kept at 100% water-holding capacity.
Infection percentage and disease severity calculation: Theinoculated
faba bean plants through the six faba bean genotypes as a parents materials
and the non-inoculated (control) were counted and calculated as percentage of
BYMV incidence in relation to total plant in each one. Hence, three weeks after
inoculation, the percentage of infection and disease severity the following
rating scale was used to determine, 0 = No symptoms; 1 = Light Leaf roll in
upper leaves; 2 = Yellow and Leaf roll in upper leaves; 3 = Mosaic, Yellow and
Leaf roll in upper leaves and 4 = Severe Mosaic, Yellow and Leaf roll in upper
leaves. Percentage of Disease Severity (DS) values were calculated using the
following formula according to Yang et al. (1997).
Non-inoculated pots of faba bean plants from each generation were used as a
control. All plants tested were checked for BYMV by direct-ELISA test and no
chemical treated were applied to the plants during the green house assay.
Statistic analysis: Chi-square tests were used to determine good ness of fit to hypothesized models based on observed and expected numbers of resistant and susceptible individuals in F2 and F3 populations.
Reactions of the six faba bean genotypes (Tribe White, Giza 3, Giza 714, Giza
429, Sakha 1 and BPL 710) as a original parents materials to BYMV infection
were evaluated, hence select and determine the two parents considering.
||Interaction between faba bean parental plants and BYMV
||Calculated percentage of infection and disease severity with
BYMV in faba bean parental cultivars
|*No. of symptomatic plant (S)/No. of total treated plants
The results presented in Table 1 show the symptoms accompanied
with genotypes as a result of their interaction with BYMV, whereas, the faba
bean genotype Giza 3 exhibited severe mosaic, yellow and leaf roll in upper
leaves, BPL710 exhibited no clear symptoms.
Data concerning the percentage of infected plants and the diseases severity were and presented in Table 2.
The results showed that parent cultivar Giza 3 revealed highest percentage of artificial infection (83.33%) followed by parent cultivar Giza 714 (73.33%).On the contrary, the lowest percentages of artificial infection was obtained by parent cultivar BPL 710 (0%). On the other parent cultivar Giza 3 gave the highest percentage of disease severity. The lowest percentage of disease severity was noticed in parent cultivar BPL 710.
Regarding to the inheritance of resistance to BYMV in Vicia faba varieties and these were genetically characterized, so we are considering presenting our results and discussion aiming this approach.
The F1s crosses which resulted between the resistant and susceptible
faba bean parents were exhibited uniformly resistant and presented in Table
3. Also, it can conducted that all ten F2s populations
were segregated close to be at the ratio of 1 susceptible:3 resistant. When
all F2s generations were pooled the chi-square analysis value (χ2)
indicated a very close fit (p = 0.96) to the 3:1 ratio (Table
The F3 families as a progenies originated from the resistant F2
families plants were either uniformly resistant or segregated 3. Resistant:1,
susceptible, distinguishing the homozygous from the heterozygous F2
parent. However, the only exception was the susceptible F3 progeny
family (No. 20) from a putative resistant F2 plant which was obviously
a false resistant (Table 4). The F3 families from
the susceptible F2 plants were uniformly susceptible. Also the resistant
plants in F3s number 4, 13, 16, 18 and 24 are probably escapes
due to irregular infection incidence by BYMV in one block.
||Faba bean segregation for green house resistance to BYMV in
the F1 hybrids and ten F2 populations
|F1 from a resistantxsusceptible cross. a, b, c,
d F2s originating the F3 families
||Faba bean segregation for green house resistance to BYMV in
26 F3 families from four different F2 populations
|F3 1-5 from F2 a ; F3 6-13
from F2 b; F314-18 from F2 c and F319-26
from F2 d (cf. Table 4)
The potential loss of effective pesticides has created strong incentives to
develop effective alternative methods for virus, BYMV control. Therefore, the
use of resistant cultivars is the most desirable control method because it provides
a practical, long-term and environmentally benign means of limiting the damage
from the diseases in general (Wang et al., 2001).
In respect to the findings in Table 1 and 2,
we selected the resistant plants of faba bean genotype Parent No. 20,
P (BPL 710.) with no disease symptoms (R, resistance) as well as susceptible
plants of fabe beanParent No. 2, P2 (Giza 3) showing
highest infection percentage by BYMV accompanied with highest symptoms severity.
The susceptible cultivar (Giza 3) was used earlier as indicator host for board
bean stain virus (BBSMV) by Omar et al. (1990)
and the second cultivar (BPL 710) was detected before as a resistant one in
previous work by Jellis et al. (1982). Therefore,
its supporting to our selection and good considering as a basic for inheritance
of resistance to BYMV of the crop consider. For this reason, we choosed the
both parents (BPL 710 and Giza 3) to be as a basic materials in this study.
The segregation ratios found suggest that this gene is dominant in this inbreeding
faba bean species. These findings were harmony with results reported by Cheng
and Jones (2000) and Jones (2005).
Ideally, final confirmation of the existence of gene responsible would require
inoculation of F3 generation. Progeny of F2 plants grown
from seed to individual plants to determine whether they are homozygous or heterozygous
for the susceptibility trend or are purely non-susceptible (resistant) in their
response (Shankar et al., 2002). Unfortunately,
such tests were impossible because the F2 plants infected with BYMV
were either positive response or were so stunted that no seed formed negative
response (Jones and Smith, 2005). At the same regard,
thought study on inheritance of hypersensitive resistance to BYMV in narrow-leafed
lupin (Lupinus angustifolius) was reported by Jones
and Smith (2005).
A model where a plant resistance is may be controlled by a single dominant
locus can explain the segregation presented in Table 3 and
4. This model is in agreement with the inheritance of the
adult-plant resistance described by Barnes (1968) in
broccoli and cabbage and by Jones and Smith (2005) in
Lupinus angustifolius. In the same connection, Mahajan
et al. (1995) also found during their studies on inheritance of downy
mildew resistance in Indian cauliflower that resistance character, controlled
by a single dominant locus in one cross of Indian cauliflower. In the other
studies related inheritance to diseases resistant, the resistance to downy mildew
(Peronospora parasitica) at a four-to five-leaf stage explained by a
single recessive gene in a broccoli line from the USA or at a three-to four-leaf
stage by two complementary dominant genes in a doubled-haploid line developed
from Everes broccoli (Wang et al., 2001)
whereas, probably represent a different types of the resistance which expressed
at an early stage of the growth development.
In regarding to our background in inheritance of the resistance to diseases,
we do not know how the resistance described in our research work relates to
that reported earlier in different crops by other authors, because the characterization
of current races of Bean Yellow Mosaic Virus (BYMV) and its relationship with
previous studies is impossible, since there is no collection of differential
lines to identify physiological races of BYMV. However, there is evidence of
high virulence for the BYMV pathotype present in the evaluating the field cultivated
area at Ismailia Governorate regains. In generally, faba bean, Vicia faba
accessions could be resistant to BYMV at stage of potent or specific of
age plant and then transferee to be susceptible and may be the opposite. This
depends on fierce located the nurse (BYMV) and the situation preparedness plant
the breadwinner, where the capacity to the resistance or vulnerability to infection
under the umbrella of the environmental conditions surrounding the area that
is or grow plant. In the respect, Coeiho and Monteiro (2000)
found during their studied on pathotype specific resistance to downy mildew
in Brassica oleracea at cotyledon and adult plant stages that Tronchuda
cabbage var. Murciana is resistant to isolate P005 from the UK and susceptible
to isolate P523 collected at Batalha at cotyledon and adult-plant stages. However,
natural source of extreme resistance to BYMV is found and cultivars with this
resistance bred, it is important to ensure that no new narrow-leafed lupin cultivar
is released that lacks the necrotic trait (Jones and Smith,
The resistance character in the faba bean materials which obtained in the present
work, was confirmed by the results detected by Jones and Smith (2005). They
found through their work on inheritance of hypersensitive resistance to Bean
yellow mosaic virus in narrow-leafed lupin, that four possible combinations
of crosses between the different necrotic and non-necrotically reacting genotypes,
segregation for the necrotic response in F2 progeny plants always
fitted a 3:1 ratio (necrotic: non-necrotic). Also, other resistance has high
value, because it is expressed in broccoli plants in field conditions (Wang
et al., 2001). However, the responses to inoculation and segregation
ratios which found provide evidence for the existence of one gene among the
genes control the resistance to BYMV (Jones and Smith, 2005).
Finally, the control of this resistance by a single dominant gene has good promise
for its direct use in faba bean plant breeding or for transfer to other field
To our knowledge, this is the first study in our faba bean breeding program in the Agronomy Department, Faculty of Agricture, Suez Canal University, Ismailia, Egypt, to focus on the inheritance of BYMV resistance. The inheritance of resistance to BYMV confirmed the resistance character in faba bean as has a good considering potencial for direct use in commercial faba bean breeding for transfer to other materials genotypes. Hence, it is possibility consequently become a one of the most encouraging options for the efficient management of viral/virus diseases in the near future.