الفهرس 
Effect of Heat Stress Conditions on Yield Related TraitsOnly 14 pages are availabe for public view
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Abstract
Faba bean (Vicia faba L.) is an annual, diploid (2n=2x=12), widely
distributed species and is considered to be the first leguminous crop that is grown
in Egypt. Total yield is consumed as a vegetable either green or dried seeds in
human feed hence it has high levels of protein (30% on average), carbohydrates
(58%), fiber, vitamins and minerals. In Egypt, the total production of faba bean is
still insufficient to cover the local consumption (about 28% of the local
consumption). So, there is a great need to overcome this gap between total
production and local consumption by: 1- expanding the cultivated area of faba
bean through the new reclaimed lands; where water, salinity and heat stress and
so forth are the important difficulty, as well as, 2- increasing the vertical
production through introduction of new varieties with high yield potential and the
ability to withstand different environmental stresses.
This study was carried out to evaluate the performance of seven divergent
faba bean genotypes that included: four local cultivars (Misr-1, Misr-3, Nubaria-
2 and Sakha-4), two newly released lines (NBL-Mar.3 and NBL-5) and one
exotic genotype from ICARDA (L3) under two conditions; prevailing terminal
heat stress conditions of the New Valley and adequate conditions of Ashmoun,
El-Menofia governorate during the winter growing season (2012/2013).
Several parameters were used to compare between the studied divergent
seven faba bean genotypes:
(1) Yield traits.
(2) Stress tolerance indices based on yield performance of the tested seven faba
bean genotypes under stress and non-stress environments.
(3) Biochemical markers as revealed by:
a- Polyacrylamide gel electrophoresis of seed and leaf protein
b- Four isozyme systems.
(4) Molecular markers and fingerprints analysis using two techniques:
a- Inter simple sequence repeats polymerase chain reaction (ISSR-PCR).
b- Inter-retrotransposons amplified polymorphism (IRAP-PCR).(5) Using ISSR and IRAP generating alleles for testing the existence of
genotypes variability by calculating polymorphic information content (PIC)
and discriminative power (D).
(6) UPGMA cluster analysis of the seven genotypes tested based on the ISSRPCR
and IRAP-PCR data by estimating genetic variability and analyzing the
relationships among the seven genotypes.
The yield traits of plant height, number of primary branches per plant,
number of pods per plant, number of seeds per pod, number of seeds per plant,
seed index (100-seeds weight g) and seed yield per plant(g) were measured for
the seven faba bean genotypes tested under the two experimental locations.
Significant differences were recorded among the seven genotypes for all
measured characters at both locations which may due to their different genetic
background. The stress conditions at New Valley have resulted in a reduction of
yield components and its attributes for all genotypes; this was illustrated by the
mean readings of the studied traits comparing between the two locations.
Superiority of Misr-1 genotype at Ashmoun (non-stressed) was due to its relative
advantages in number of primary branches/plant, number of pods/plant, number
of seeds/plant and seed yield/plant. Contrary, superiority of Sakha-4 genotype at
the New Valley (stressed) used to be as a result of its relative advantages in plant
height, number of primary branches/plant, seed index (weight of 100 seeds in g.)
and seed yield/plant. These results reflected the importance of these traits as
effective yield contributors and should be used as criteria for selection in future
faba bean improvement program. Regarding seed yield/plant (g), it could be
concluded that the genotype Sakha-4 (which ranked third place under adequate
conditions while ranked first under stress conditions) is the most tolerant
genotype that it was adaptable for the prevailing condition of New Valley and
gave the highest level of yielding capacity. Otherwise, Nubaria-2 is the least
tolerant one, which ranked last genotype under both non-stress conditions as well as stress conditions. The previous superior genotype i.e. Sakha-4 can be exploits
in faba bean improving programs.
Seed yield/plant (g) differences among the tested genotypes under both
locations reflect a fluctuation response in each of the used eleven tolerance
indices. This confirmed by detecting the lowest value of SSI index as well as the
highest values of GMP, HM, STI, k2STI, YI and YSI indices for Sakha-4
genotype. Therefore, Sakha-4 genotype could be considered as the most heat
stress tolerant genotype. On the contrary, Nubaria-2 genotype (which ranked last
genotype under non-stress conditions as well as under stress conditions) achieved
the highest value of SSI index and the lowest values of MP, GMP, HM, STI,
K1STI, K2STI, YI, and YSI indices, therefor, Nubaria-2 genotype could be
considered as the least tolerant one. Thus, this investigation suggested that the
results of SSI, GMP, HM, STI, K2STI, YI and YSI indices in selection of
genotypes are appropriates for selection of heat tolerant/susceptible genotypes,
and therefor to determine the most appropriate heat tolerance indices of faba bean
genotypes.
Ployacrylamide gel electrophoresis analysis of seed protein patterns
revealed forty six bands under adequate location of Ashmoun. Such bands were
detected at approximately molecular mass ranging between 107.82 and 8.61 kDa,
with polymorphism of 93.48%. Eleven unique bands represented as (M+) were
recorded. These unique bands could be used as positive biochemical markers
(M+) for the faba bean genotypes under study. Also, 12 polymorphic bands are
appeared in all studied genotypes except one, these bands are represented as (M-)
and could be used as negative biochemical markers for the faba bean genotypes
under study. While, forty four bands were recorded in seed protein patterns under
stressed location of New Valley. Such bands were detected at approximately
molecular mass ranging between 148.57 and 4.88 kDa, with 59 % polymorphism.
Four unique bands represented as (M+) were scored. These bands could be used
as positive biochemical markers (M+) for heat stress for the faba bean genotypes under study. Also, 10 polymorphic bands are appeared in all studied genotypes
except one; these bands are represented as (M-) and could be used as negative
biochemical markers for the tested faba bean genotypes under heat stress.
Ployacrylamide gel electrophoresis analysis of leaf protein patterns
revealed thirty three bands under adequate location of Ashmoun. Such bands
were detected at roughly molecular mass ranging between 359.67 and 16.45 kDa,
with polymorphism of 81.8%. Five unique bands were found and represented as
(M+). These unique bands could be used as positive biochemical markers (M+)
for the faba bean genotypes under study. Also, 8 polymorphic bands were
appeared in all studied genotypes except one, these bands were represented as
(M-) and could be used as negative biochemical markers for the faba bean
genotypes under study. Whilst, forty three bands were observed in the leaf
protein pattern under stressed location of New Valley. Such bands were detected
at approximately molecular mass ranging between 100.21 and 15.79 kDa, with
polymorphism percentage of 65.12%. Seven unique bands were scored and
represented as (M+). These unique bands could be used as positive biochemical
markers for heat stress for the faba bean genotypes under study. Also, four
polymorphic bands were appeared in all studied genotypes except one; these
bands were represented as (M-) and could be used as negative biochemical
markers for the tested faba bean genotypes under heat stress.
Native polyacrylamide gel electrophoresis was used to detect isozyme
fingerprints of the seven faba bean genotypes tested under both adequate and
stressed locations and to detect biochemical markers for faba bean tolerance to
heat stress. This was done using four isozymes including α- esterase, peroxidase,
alkohol dehydrogenase and polyphenyl oxidase. In this concern, under adequate
location of Ashmoun, a total of twenty one bands were recorded by the four
isozymes patterns with 47.6% polymorphism. Different values of polymorphism
were detected in the seven genotypes under study, ranging from zero % (α-
esterase) to 100 % (polyphenyl oxidase). Peroxidase patterns gave two unique bands (Px3 and Px4) and scored in the NBL-5 genotype which could be used as
biochemical marker for this genotype under non-stressed conditions. Also,
among the polymorphic bands of all patterns two bands out of them i.e. Px2 and
PPO1 were present in all genotypes except NBL (Mar.3) and L3 respectively,
and could be used as negative biochemical markers for these genotypes.
Otherwise, under stressed location of New Valley, a total of twenty five bands
were recorded by the four isozymes patterns with 72 % polymorphism. Different
values of polymorphism were detected in the seven genotypes under study,
ranging from 33 % (α-esterase) to 100 % (peroxidase). Peroxidase patterns gave
one unique band (Px3) and scored in the more tolerant genotype Misr-1 and
could be used as a biochemical marker for this genotype under heat stress
conditions. Also, polyphenyl oxidase patterns gave three unique bands (PPO4,
PPO6 and PPO8), which scored in the least tolerant genotype Nubaria-2,
therefore these bands could be considered as biochemical markers for heat stress
susceptibility. Furthermore, two bands (Est3 and Est4) were shared polymorphic
ones and existed in the two more tolerant and most tolerant genotypes Misr-1 and
Sakha-4, therefore these bands could be considered as biochemical markers for
heat stress tolerance.
Ten oligonucleotide primers were used to establish ISSR-PCR fingerprints
of seven faba bean genotypes. A total number of 85 amplicons (amplified
fragments) were generated, with 88.2% polymorphism. The highest percentage of
polymorphism (100 %) was detected with each of the primers B44, 17898B, HB-
10, HB-13, HB-14 while the lowest one (57.1 %) was recorded in the primer HB-
09. The ISSR-PCR fragments generated by using the ten primers could be
used as genotypic specific markers. A total of 26 specific markers including
either the presence (M+) or absence (M-) were identified out of the total amplified
fragments in the tested genotypes, and they could be considered as marker
assisted selection (MAS) for heat stress tolerance and as molecular fingerprints
for tested genotypes. Values of polymorphic information content (PIC) and discriminating power (D) indicated that primer HB-14 was the most efficient to
analyze genetic variability among faba bean genotypes with values of 0.99 and
0.889, respectively, followed by primers 17898B and HB-10.
A whole of 141 amplicons (amplified fragments) were generated via the
ten IRAP primers, with 87.3% polymorphism. The highest percentage of
polymorphism (100 %) was detected with each of the primers (4314) and (4373),
while the lowest one (50 %) was recorded in the primer (4362). The IRAP-PCR
fragments generated by using the ten primers could be used as genotypic
specific markers. A total of 60 specific markers including either the presence
(M+) or absence (M-) were identified among the ten primers; such bands could
be considered as molecular markers (marker assisted selection) for heat stress
tolerance as well as molecular fingerprints for the tested genotypes. Values of
PIC and D indicated that primer 4376 was the most efficient to analyze genetic
variability with values of 0.988 and 0.935, respectively, followed by primers
4314 and 4374.
UPGMA cluster analysis of the seven genotypes tested based on the ISSRPCR
and IRAP-PCR data revealed that, Nubaria-2 (least tolerant) genotype
represented as a separate phenetic line which had the lowest similarity values
with all other genotypes. The other genotypes were classified into two main
clusters. The first cluster included three genotypes (L3, NBL-5 and NBL-Mar.3);
it is worthy to note that, these three genotypes include one common ancestor;
hence, this confirmed the high similarity value between them. The second cluster
included three genotypes represented by a separate phenetic line that comprises
Sakha-4 (most tolerant) genotype and a sub-cluster comprises Misr-3 and Misr-1
genotypes, also it is worthy to note that Misr-1 genotype is one of the ancestors
of Misr-3 genotype.