Characterization of wheat (Triticum aestivum L.) genotypes for disease reaction against spot blotch pathogen
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Date
2017
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Dr. Rajendra Prasad Central Agricultural University, Pusa (Samastipur)
Abstract
Wheat (Triticum aestivum L.) is the largest consumed cereals and most important element in the diet of the poor. Successful production of the wheat in the warmer regions of South Asia is constrained by several biotic and abiotic stresses. Spot blotch of wheat caused by Bipolaris sorokiniana is one of the most significant biotic stresses which limits the production and productivity of the crop in the region. Under present investigation eighty-eight genotypes of wheat were evaluated for the purpose of twelve morpho-metric traits and reaction against spot blotch disease in randomized block design (RBD) during rabi, 2015 Molecular characterization using 17 SSR markers (associated with tolerance against spot blotch disease) was also undertaken to as certain the genetic diversity among the studied genotypes Observations on 1000-grain weight, grain filling duration (GFD), no. of tiller per plant, canopy temperature, yield per plot, heading, days to greenness, disease severity and area under disease progress curve (AUDPC), lesion size, leaf tip necrosis, biomass per square meter were recorded. Significant differences were observed among the genotypes for all the traits under consideration. Genotype × environment interactions were found non-significant.
Molecular characterization work revealed a total of 232 alleles in 19 genotypes using 17 SSR markers. The number of alleles per locus varied from four in Xgwm371 to thirty in Xgwm 445 with an average of 11.04 alleles per locus. Total 165 unique alleles were observed at 21 SSR loci, with an average of 7.85 unique alleles per locus. The number of unique alleles per locus ranged from one in Xgwm 371 to twenty six in Xgwm 445. Out of 17 SSR primers 10 showed null alleles. The maximum 4 genotypes (Ariana, Dharwad Dry, Ciano T 79 and HD 2967) exhibited null alleles for the primer pair Xgwm 120. Stutter bands were also detected in the present investigation. Such bands were observed in the case primer pairs, Xgwm-611, Xgwm-159 Xgwm 132, Xgwm 445, Xgwm 371, Xgwm146, Xgwm 425. The PIC values varied from 0.435 in the case of Xgwm120 to 0.959 in the case of Xgwm 146 with an average of 0.876 across the primer, indicating that the markers were highly informative (PIC>0.5). The use of SSR markers in the present analysis exhibited a remarkably higher level of genetic polymorphism and allowed unique genotyping of the genotypes included in the analysis. The nineteen genotypes classified into five different clusters or groups (I to V) at 22 phenon level based on cluster analysis using the UPGMA method based on Dice coefficients.
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