Abstract Kernel hardness is one of the most important characterizations on end-use quality of bread wheat and also used for marketing classification. Kernel texture, mainly controlled by one major locus (Ha) located on the short arm of chromosome 5D. Two tightly linked genes as puroindolin a and b covered by this major locus and designed as Pina and Pinb respectively. When both puroindolines are in their ‘functional’ wild state, grain texture is soft. When either one of the puroindolines is absent or alter by mutation, then the result is hard texture. In this study, 61 Iranian commercial and 92 landrace cultivar were investigated for their kernel hardness and puroindoline alleles using SKCS and, PCR and cleaved amplified polymorphic sequences (CAPS) techniques respectively. Two pairs of specific primers were used to amplify Pina and Pinb. The results indicated that frequency of soft, mixed and hard genotypes were 65.6, 19.6 and 14.8% respectively, in commercial and 58.7, 13 and 28.3% in landrace cultivars. Among hard type of commercial cultivars, 18 and 5, genotype belonged to Pina-D1b and Pinb-D1b respectively. Kavir was only cultivar with Pinb-D1e allele. Pinb-D1b allele was identified in two hard type of landrace cultivars. Surprisingly Pinb-D1c was found in none of cultivars. Influence of the above proindoline alleles on kernel hardness showed that the SKCS hardness index of Pina-D1b (average 72.12) was significantly higher than that of Pinb-D1b (average 63.37). Our knowledge about the genetic basis of kernel hardness could provide useful information in breeding programs of bread wheat.

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