Genetic and molecular analysis of drought tolerance in wheat (Triticum aestivum L.em.Thell)
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Date
2013
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CCSHAU
Abstract
The present investigation was carried out to elicit information on the nature of gene effects for yield and its components, genetic variability under different environments and characterization of phenotypic and genotypic variability of F2 population of cross DBW 17 x WH 1080 using SSRs in wheat (Triticum aestivum L. em. Thell). The experimental material comprised eight genotypes viz. WH 730, WH 283, PBW 343, Raj 3765, DBW 17, WH 1080, HD 2967 and KRL 210. A diallel set of 8 x 8 was prepared by crossing these genotypes in all possible combinations (excluding reciprocals). Parents and their F1 generations were planted during rabi, 2011-12 in randomized block design with three replications under normal and late sown conditions. Two parents of one cross (DBW 17 x WH 1080) and their 200 F2 plants were grown under drought (late sown) environment. The observations were recorded on five randomly selected competitive plants in parents, F1s and on 200 plants in F2 population of cross DBW 17 x WH 1080 for thirteen traits. Analysis of variance indicated presence of adequate genetic variation due to genotypes in both the environments. Combining ability analysis was performed by employing method 2, Model-I of Griffing (1956) which revealed that the mean squares due to GCA and SCA were significant for all the traits in both environments, except GCA of chlorophyll fluorescence in stress and SCA for chlorophyll content in normal environment. The magnitude of gca component (gi2) was higher than sca component (sij2) for days to heading (0.941), days to anthesis (1.223), days to maturity (0.870) and plant height (8.990) in stress environment, indicating that these traits were mainly under the control of additive genetic variance. An overall appraisal of GCA effects revealed that PBW 343 and HD 2967 were good combiners for the majority of traits in both the environments. High GCA effects are related to additive gene effects or additive x additive interaction effect which represent the fixable genetic component of variation. For grain yield the crosses PBW 343 x WH 1080 and WH 730 x PBW 343 in normal environment were found promising and crosses WH 1080 x HD 2967 and WH 730 x PBW 343 in stress environment were identified as promising on the basis of their high per se performance, average heterosis and heterobeltiosis and with high significant SCA effects. A total of 42 alleles were detected in 106 F2 plants and number of alleles per locus ranged from 1-3 with an average of 2.10 alleles per locus. NTSYS-pc based two dimensional PCA analysis showed scattering of the F2 population between the two distinct parental genotypes. Genetic similarity analysis showed that parental genotypes were quite distinct from each other. In the cross DBW 17 x WH 1080 the dendrogram constructed and clustered in eight major groups. The markers expressed between 3.70 and 18.00 per cent of the phenotypic variation in drought condition. Xgwm573 was found to be associated with days to heading and days to anthesis while, Xgwm369 was found to be associated with 1000-grain weight, coleoptile length and chlorophyll content. These SSRs may be used for further genetic manipulation of drought tolerance in wheat after further validation.
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Keywords
Developmental stages, Environment, Yields, Wheats, Grain, Crossing over, Planting, Genetics, Heterosis, Chlorophylls