Characterization of wheat (Triticum aestivum L.) genotypes with respect to heat stress tolerance and spot blotch resistance
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Date
2015
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Rajendra Agricultural University, Pusa (Samastipur)
Abstract
Twelve wheat (Triticumaestivum L.) genotypes were characterized with respect to heat stress and spot blotch diseaseunder four environmental conditions viz. no stress (E1), stress due to spot blotch (E2), heat stress (E3) and combined stress (E4) alongwith molecular characterization using 28 SSR markers(associated with tolerance against heat stress and resistance against spot blotch disease). The experimental materials were evaluated in randomized block design (RBD) factorial. Observation on 1000-grain weight, grain filling duration (GFD), plant height, peduncle length, spike length, disease severity and area under disease progress curve (AUDPC) were recorded. Significant differences were observed among the genotypes for all the traits under consideration. Genotype × environment were found non-significant. The lowest performance of the genotypes under combined stress condition (E4) was recorded. The individual impact of heat stress with respect to performance of the genotype was found significantly higher than that caused by spot blotch disease. Raj 3765 for 1000-grain weight, WH 760 for GFD, Yangmai-6 for plant height, PBW 343 for peduncle length and HD 2733 for spike length, showed stable performance across the environment. On the basis of stress susceptibility index (SSI) the genotypes WH 760, DBW 14 and Raj 3765 were found better for the characters, 1000-grain weight and GFD. The overall disease severity was found maximum under heat stress condition. Similarly genotypes were having relatively more AUDPC under heat stress condition.
The twenty eight SSR markers detected total 244 alleles in 12 genotypes, the number of alleles per locus varied from four in Xgwm133a and Xgwm456 to twenty three in Xgwm293with an average of 6.5 alleles per locus. A total 158 unique alleles were observed at 37 SSR loci, with an average of 5.6 unique alleles per locus. The number of unique alleles per locus ranged from one in Xgwm273 to twenty two in Xgwm293. In set of 12 varieties, 6 SSR loci showed null alleles, in case of primer pair Xbarc1047, Xgwm133a, Wmc168,cfd44, Xbarc147 and Xgwm626.The polymorphism information content(PIC) values revealing allele diversity and frequency among the entries varied from 0.292 in the case of Wmc273 to 0.902 in the case of Xgwm356 with an average of 0.763 across the primer. Pair-wise genetic similarity coefficient, widely varied from 0.72 to 0.82 indicating a considerably greater extent of variation among the wheat genotypes. High degree of similarity coefficient exists between wheat genotypes Raj 3765 and PBW 343 (0.828) or WH 760 and DBW 14 (0.828), whereas Sonalika and HD 2967 (0.721) weremost distantly related. Cluster analysis grouped twelve wheat genotypes into four different clusters (I to IV) at 35 phenon level, the use of twenty eight SSR markers allowed unique genotyping of twelve genotypes included in the analysis.
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