Daisy Basandrai

Harnessing genetic potential of wheat germplasm banks through impact-oriented-prebreeding for future food and nutritional security

The value of exotic wheat genetic resources for accelerating grain yield gains is largely unproven and unrealized. We used next-generation sequencing, together with multi-environment phenotyping, to study the contribution of exotic genomes to 984 three-way-cross-derived (exotic/elite1//elite2) pre-breeding lines (PBLs). Genomic characterization of these lines with haplotype map-based and SNP marker approaches revealed exotic specific imprints of 16.1 to 25.1%, which compares to theoretical expectation of 25%. A rare and favorable haplotype (GT) with 0.4% frequency in gene bank identified on chromosome 6D minimized grain yield (GY) loss under heat stress without GY penalty under irrigated conditions. More specifically, the ‘T’ allele of the haplotype GT originated in Aegilops tauschii and was absent in all elite lines used in study. In silico analysis of the SNP showed hits with a candidate gene coding for isoflavone reductase IRL-like protein in Ae. tauschii. Rare haplotypes were also identified on chromosomes 1A, 6A and 2B effective against abiotic/biotic stresses. Results demonstrate positive contributions of exotic germplasm to PBLs derived from crosses of exotics with CIMMYT’s best elite lines. This is a major impact-oriented pre-breeding effort at CIMMYT, resulting in large-scale development of PBLs for deployment in breeding programs addressing food security under climate change scenarios.

Resistance to powdery mildew (Blumeria graminis f. sp. tritici E. Marchal.) in bread wheat, durum, dicoccum and triticale genotypes

Powdery mildew resistance genes were postulated in 63 Indian genotypes belonging to Triticum aestivum L., T. durum, T. dicoccum and triticale. Gene Pm3c in combination with some unidentified gene(s) was postulated in genotype, K 9441. Some unknown gene(s) alongwith Pm5 were identified in eight genotypes, while Pm 5+Pm 8 were detected in genotype WH 681. Resistance in 22 genotypes was attributed to gene Pm8 while, 12 genotypes showed additional resistance ascribed to the unknown gene(s). Seven genotypes viz., K 9453, HD 2689, HW 3003, HD 2680, MACS 3011, MACS 3018 and HD 2700 showing differential behavior to the test cultures. However, infection type matching technique, could not attribute resistance in these gnotypes. Triticale genotypes viz., DT 95, DT 46 and DT 91, Triticum dicoccum genotypes namely, DDK 1013, DDK 1014, MACS 2574, MACS 2912, MACS 2919, DDK 1009 and DDK 1015 and T. aestivum genotype UP 2450 were resistant to all the cultures and hence, no resistance gene in these genotypes could be postulated.