Allelic Distribution of Puroindoline Genes Affecting the Grain Hardness in Some Iranian Bread Wheat Cultivars

Abstract

Grain hardness is an important characteristics influencing end-use quality of bread wheat. Wheat with the hard grain texture has higher protein content and more intensive gluten that leads to production of higher bread quality. However, soft texture wheat has lower protein content and weaker gluten, which are suitable for cake and candy production. Grain hardness is determined by the Pina and Pinb genes that are located on the short arm of chromosome 5D. In this study, 83 bread wheat cultivars were characterized for the allelic distribution of Pina and Pinb genes using allele specific markers. At the Pina locus, Pina-D1a and Pina-D1b alleles were observed in 64% and 36% of varieties, respectively. However, at the Pinb locus, 90% of varieties showed Pinb-D1a and 10% had Pinb-D1b allele . Based on the grain hardness index which was measured with the NIR, varieties whit the value less than 50 were considered as soft while above 50 were considered as hard grain texture. The results of marker-trait association showed that Pina had the significant effect (P= 0.019) on the grain hardness, as cultivars with the Pina-D1a allele were significantly softer (49.85±0.37) that those with the Pina-D1b allele (51.38±0.50). The results of regression analysis showed that for the traits including bread volume, grain hardness and water absorption as dependent variables, Pina was entered to the model. The results of this study can help wheat breeders to effectively select parents for the grain hardness in the MAS breeding programs.