Introgression of Drought Tolerance QTLs in Rust Resistant Recipient By Using Marker Assisted Backcrossing Breeding (MAB) Approach.

Rust diseases and drought are major constraints to wheat production worldwide. Developing drought and rust resistance varieties are most promising and economically viable solution for improving yield stability under drought-prone conditions. The objective of this study was to introgression of drought tolerance (DT) QTL regions in a leaf and stripe rust resistant line using a backcross population derived from cross of advance breeding line PBW703 (PBW343+Lr24+Lr28+Yr10+Yr15) and Babax, a CIMMYT derived drought tolerant line. Total of 82 SSR markers reported to be linked to DT in various studies were assayed on the parents and out of 24 polymorphic markers, 15 markers showed introgression on 1B, 1D, 2D, 3B, 4A, 5A and 6D chromosomes. By molecular analysis of 95 BC₂F₁ plants, 44 plants were found to carry leaf rust (Lr24 and Lr28) and stripe rust (Yr10 and Yr15) resistance genes, out of which 43 plants were found to carry the Babax specific allele for the markers from the genomic regions carrying drought tolerance QTL. For phenotypic analysis, 364 BC₂F₄ progenies were evaluated for rust reaction, chlorophyll content, canopy temperature, stay green, plant height, number of tillers per meter, number of spikelets per spike, number of grains per spike, 100 grain weight under restricted irrigated conditions. Analysis of variance showed the presence of significant differences among the BC₂F₄ progenies for given morpho-physiological traits. The 46 transgressive segregants were observed for all the traits and these segregants were also assayed with 15 markers that were associated with DT genomic regions. These improved lines will be used to improve the drought and rust resistance in the wheat breeding program.