Development of genetic and genomic resources for Downy mildew resistance and low ODAP content in Lathyrus sativus L.
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Date
2023-12-20
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Agricultural Biotechnology, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, Nadia – 741252
Abstract
Grasspea (Lathyrus sativus L.) belongs to the family Fabaceae and the tribe Vicieae having
chromosome number (2n = 2x = 14). India is the largest producer of lathyrus which is the
third most important pulse crop after chickpea and pigeon pea. It is one of the most
important climate resilient crops which thrive well not only in extreme weather and stressed
condition but also in poor soil. It is a good source of dietary proteins and is used as food and
fodder including improvement of soil fertility. The cultivation of this crop is neglected due to
the presence of anti-nutritional compound β-N-oxalylamino-L-alanine (BOAA) or β-N-
oxalyl-L-α, β-diaminopropionic acid (ODAP) which is considered as causative agent of the
disease Lathyrism, the paralytic disorder. In recent past, many breeders started working to
develop low-ODAP lines like Ratan, Prateek and BioL-212 etc. containing ~ 0.2% ODAP.
Among different biotic factors, downy mildew (Peronospora lathi-palustris) poses a serious
threat in case of water stagnation during winter rains. On the other hand, introgression of
disease resistance gene leading to increase yield has also been initiated in grasspea using
marker assisted selection. Therefore, it is necessary to develop trait linked molecular markers
for marker assisted breeding for developing new Lathyrus varieties. The present work was
aimed to screen out the segregants, from F2 and F3 population derived from two different
cross combination, Berhampore local x Mahateora and Mahateora x BioL-212 attributed
with high grain yield coupled with zero/negligible ODAP content and resistance to downy
mildew resistance. In the present study, the segregating population (F2 and F3) developed
from two sets of crosses (Mahateora x BIO L-212 and Berhampore Local x Mahateora) were
characterized. Simple Sequence Repeats (SSR) marker-based assessment was done for
parents and segregating populations in search of trait associated marker and to deduce
molecular diversity. A total of 120 SSR markers including 30 EST-SSR were used for
molecular diversity and screening for association with ODAP and /or Downey mildew.
All morphometric traits were statistically significant in segregating populations derived from
both the parental crosses. Based on the mean seed yield plant-1, the F2 segregants MBiF2-1,
MBiF2-2 MBiF2-4 and three F3 Segregants MBiF3-43, MBiF3-54, and MBiF3-52 from
Mahateora x BioL-212 as well as from Berhampore Local x Mahateora, F2 segregants
BLMF2-23, BLMF2-37 and BLMF2-50 and F3 segregants BLMF3-46, BLMF3-143 and
BLMF3-100 were found very promising. Low ODAP content (≤0.1%) was found in BLMF3-
32, BLMF3-78, BLMF3-8, BLMF3-186, BLMF3-39, BLMF3-46 and BLMF3-211. With
respect to the percent disease incidence (PDI), the identified resistant segregants to Downy
mildew were BLMF3-128 (2%), BLMF3-8 (4%), BLMF3-36, (12%) BLMF3-39 (12%),
BLMF3-195 (14%) and BLMF3-100 (18%). The PDI was highest in BLMF3-38 (44%).
Based on highest seed yield/plant (>20 g), low ODAP (≤0.1%) and PDI (<12%), the most
promising segregants identified were BLMF3-39, BLMF3100, BLMF3211, BLMF3168. The
seed yield/plant were found to be significantly and positively correlated at both genotypic and
phenotypic level with Plant height, number of branches plant-1, number of pods plant-1, pod
length, number of internodes plant-1 and number of seeds pod-1. The Regression model
identified number of pod plant-1, 100 seed weight, number of seeds pod-1 and pod length in F2
of the crosses where as in the F3 population of Berhampore Local x Mahateora, number of
pods plant-1, number of seeds pod-1, number of internodes plant-1, 100 seed weight, plant
height and number of branches plant-1 were considered as the better explanatory variables. No
significant differences between GCV and PCV were found for most of the traits, indicating
lesser influences of environmental factors. High heritability coupled with high Genetic
advance over mean for plant height, number of branches plant-1, number of pods plant-1, and
seed yield plant-1 were recorded to be used for indirect phenotypic selection. Multivariate
analysis based on morphometric parameters from the segregants from Mahateora x Bio L-212
viz, MBiF2-49, 2, 4, 55, 46, 20, 11, 19, 52, 33, 25 and MBiF3-52; from Berhampore Local X
Mahateora the segregants BLMF2-27, 56, 30, 37, 50, 59 and, BLMF3-128, 143, 46, 211, 100,
168 and 39 were found as the diverged genotypes. Molecular diversity based on SSR
genotyping formed 7 distinct groups where Cluster V was found to be the largest with 15
cluster members. Based on higher Polymorphic Information Content (PIC) and Marker Index
(MI) value, the SSRs namely c39279_g1_i12, c46049_g2_i1, c34810_g1_i1, c35787_g1_i1,
c43114_g1_i1, c46949_g2_i1, c13442_gi_i1 and S-168 could be used in molecular diversity
analysis in lathyrus for future breeding programme. From the study, the EST-SSR marker
c31994_g1_i1 and c35336_g1_i4 were found putatively associated with low ODAP content
from both F2 and F3 population. In the F3 population c39249_g1_i1 and S-159 showed
association with downy mildew resistance.