Combining grain protein (GpcB1) and stripe rust resistance (Yr) genes in the background of high yielding genotypes: Since proteins are the binding site for zinc in the grain, improving grain protein content is expected to increase grain zinc concentration. With this objective, research efforts were made to introgress grain protein gene (GpcB1) into elite wheat cultivars like HD 2967, DBW 17 and HD3086. Since the recipient varieties have become susceptible to stripe rust, crosses were attempted to introgress Yr genes along with GpcB1 gene. During 2016-17, wheat breeding material was generated for pyramiding of grain protein content gene (Gpc-B1) and stripe rust resistance gene(s) Yr 5 or Yr 40/Lr57 in the background of wheat varieties DBW 17 (F3 generation) and HD 2967 (F2). Besides crosses were also initiated using HD 3086 as recipient parent.
Evaluation of Backcrosses: A set of high grain micronutrient wheat backcross derivatives was screened for the estimation of variation present for the phytic acid content. Two sets of 210 BC1F3 and 210 BC2F3 lines generated by crossing advanced backcross lines of T. durum with grain zinc QTL introgressed from T. monococcum and T. boeoticum in high yielding variety as recipient parent back ground was taken as a base material. Among those wheat backcross lines, 107 genotypes from BC1F3 and 93 genotypes from BC2F3 were selected on the basis of high grain iron and zinc concentration and rust resistance. The phytic acid content of the selected genotypes was assessed that ranged from 10.92 – 63.93 mg/g of whole wheat meal. Thirty-five promising genotypes were further shortlisted with the combination of high grain iron and zinc concentration, low phytic acid content and rust resistance. Three ear to row progenies from each shortlisted genotype were sown at Keylong research station during off season for generation advancement.
In another experiment, BC1F5 and BC2F5 progenies with high grain micronutrient and low phytic acid content were evaluated for morphological and grain quality parameters. The variation in the genotypes was significant for all the traits except the grain iron concentration. For the grain zinc concentration the genotype from the cross WH 1105*3/BF20 possessed highest zinc concentration among all the genotypes and for the phytic acid content the genotype from the cross PBW 698*3/BF22 showed lowest phytic acid content among all the genotypes. Moreover, it was having high zinc concentration as well. Although the genotype has the combination of both traits i.e. high grain zinc and low phytic acid content but it was found to be poor yielding. Analysis of variation and correlation studies showed that the genotypes which possess high grain protein content and grain zinc concentration were low yielding with less number of grains per spike, late maturity and relatively more plant height. Phytic acid content did not show significant correlation with any of the traits studied.