Association of puroindoline sequence type and grain hardness in hard red spring wheat

Wheat (Triticum aestivum L.) endosperm texture is a primary determinant of milling and end-product quality. Friabilin, a marker protein for grain hard ness, is composed of two proteins, puroindoline a and b (pinA and pinB, res pectively). Hard-textured wheats have variant alleles consisting of a glyci ne-to-serine change in pinB (pinB-D1b) or the complete absence of pinA (pin A-D1b). Our objectives were to examine the influence of pinA and pinB alter ations on grain hardness from populations among elite hard red spring wheat cultivars differing in puroindoline alteration, and to measure association s of gain hardness with kernel weight and grain protein concentration. Fift y F-3:6 progenies from three pinA-D1b x pinB-D1b, one pinB-D1b x pinB-D1b, and one pinA-D1b x pinA-D1b type crosses were evaluated with their parents in two field experiments. Lines classified as pinA-D1b were significantly h arder than lines classified as pinB-D1b when averaged across the three segr egating populations. This difference was significant (P < 0.05) in one of t he three populations. Significant genetic variation existed for grain hardn ess, protein concentration, and kernel weight within puroindoline classes a nd among lines from crosses not segregating for pinA-D1b vs. pinB-D1b. Sign ificant positive correlations were observed in all five populations for gra in hardness and protein concentration (r = 0.46-0.79). Our results indicate that most of the genetic variation in grain hardness among the populations studied was due to factors other than pinA and pinB, as the pinA-D1b vs. p inB-D1b difference explained <12% of the variation in grain hardness in the se hard wheat populations.