Molecular cytogenetic analysis of rye chromatin introgressed bread wheat recombinants for drought tolerance and yellow rust resistance

Abstract

The present research endeavor was undertaken to accelerate the wheat improvement programme through development, detection and characterization of rye introgressed bread wheat recombinants at in vitro and in vivo level for drought tolerance and yellow rust resistance. Five triticales, Himalayan rye and various wheat genotypes were utilized as the parents in the wide hybridization programme. Among the different wheat genotypes, C-306, VL-829 and Tyari-3 had highest seed setting frequency of 30.67 per cent, 27.27 per cent and 17.41 per cent, respectively, in wheat x rye hybridization programme. The triticale x wheat and wheat x rye recombinants were further subjected to Imperata cylindrica mediated chromosome elimination approach of doubled haploidy breeding. The variability in the haploid induction parameters was observed to be under genetic control for embryo formation and regeneration, while pseudoseed formation was only affected by auxin treatment. Among the different generations, the backcross generations viz., BC1F1 and BC1F2 were found to exhibit significant positive response towards haploid induction parameters in both triticale x wheat and wheat x rye hybridization. The detection of new recombinants for introgression of rye chromatin through molecular cytogenetic analysis revealed 1BL.1RS translocation in 33 lines (55.93 per cent), 1BL.1RS translocation along with substitution in 5 lines (8.47 per cent), 1BL.1RS translocation along with addition in 8 lines (13.56 per cent), substitution of single pair of rye chromosomes in 5 lines (8.47 per cent) and addition of rye chromatin in 1 line (1.69 per cent). While 7 lines were found with no rye chromatin. To validate the effect of rye introgression on drought tolerance and yellow rust resistance, all 59 recombinants were evaluated under well watered and water stressed conditions at in vivo and in vitro level. Analysis of variance revealed sufficient genetic variability among genotypes for different traits at both in vivo and in vitro levels. Under field conditions, direct influence of rye introgression was observed on plant height, grain yield, biological yield and harvest index. The screening for drought tolerance under in vitro conditions revealed positive significant effect of rye introgressions on germination percentage, shoot length, root length, root number, coleoptile length and seedling vigour index. Overall, 1BL.1RS translocations and substitutions were found to exhibit significant influence on most of the drought parameters. The screening for yellow rust resistance revealed differential disease reaction, where 52 recombinants were observed to be resistant. The lines exhibiting superiority for the traits can be used as a parental source in wheat improvement endeavors.