Bains, N.S.Rupinder Pal Singh2016-08-192016-08-192016http://krishikosh.egranth.ac.in/handle/1/73072Parents and derivatives crosses PBW 621 X HD 2967, PBW 621 X PBW 343, HD 2967 X PBW 343 and PBW 636 X PBW 343 involving stripe rust resistant lines and highly susceptible cultivar PBW 343 were studied. Characterization of parental lines namely against 78S84 pathotype highlighted gradual and continuous shift in resistance over four seasons (2011-12 to 2014-15) depicting the increasing aggressiveness pathotype. F2 and F3 analysis of cross PBW 621 X HD 2967 revealed the additive nature of the genes involved as also the fact that each parent is contributing one gene towards resistance. Crosses PBW 621 X PBW 343 and HD 2967 X PBW 343 supported that each parent contributes one gene towards resistance. Contrary to the expectations, highly susceptible parent PBW 343 also contributed a resistance gene in the R X S crosses. Over these years, PBW 636 showed diminishing resistance levels against 78S84 pathotype, ultimately succumbing completely. Cross PBW 621 X HD 2967 was chosen for molecular marker tagging as a clear genetic basis of resistance was evident from the segregation pattern. Out of total 327 SSR primers used, 95 polymorphic primers were put to use in bulked segregant analysis of 20 individuals in each pool. Primers wmc 235 and wmc 75 showed single parent alleles in the bulks. HD 2967 allele of primer wmc235 was found only in resistant bulk while PBW 621 allele of primer wmc75 was also found only in susceptible bulk. A fresh set of 26 extreme individuals selected from F3 based on their stripe rust score were subjected to marker analysis with the two identified primers. The number of homozygous progenies for the two extreme categories was equal as per the genetic expectations. Thus there is a good indication that the two genes are not linked. Additional markers need to be used to map these genes. Evaluation of high yielding resistant genotypes (F6) derived from cross PBW 621 X HD 2967 was conducted in 2013-14and 2014-15. Promising lines were identified for use in the breeding programme. Two of these lines viz; BWL 4438 (PBW 709) and BWL 4443 (PBW 724) were promoted to national co-ordinate trials. An experiment was conducted to refine pre-regeneration chromosome doubling in wheat DH production using alternate antimicrotubular compounds APM and Trifluralin was scrutinised. APM 250 μm enhanced embryo formation frequency to 24.15 per cent and Trifluralin 250 μm was significant in increasing plant regeneration frequency to 57.69 per cent as compared to 18.20 per cent and 41.42 per cent in control (colchicine 0.2%) treatment. Combination of APM and Trifluralin at (125 μm each) enhanced both embryo formation frequency (21.50 per cent) and plant regeneration frequency (52.24 per cent).enTriticum aestivum, Puccinia striiformis f. sp. tritici, pathotype 78S84, inheritance of resistance, additive gene actionThesis