Abstract:

Grain texture is one of the characteristics of bread wheat (Triticum aestivum L.) quality and has an important influence on wheat milling and processing quality. Puroindoline gene, mainly controlling grain texture of bread wheat, locates on the short arm of dismal 5D chromosome and is divided into Pina and Pinb genes tightly linking together. Pina and Pinb with the coding sequence of 447 bp have no any intron and form the basis of molecular genetics of grain texture in bread wheat. Up to now, lots of haplotypes of Pina and Pinb genes have been identified in bread wheat and Aegilops tauschii. Of them, Pina-D1b allele with hardest grain texture among the known haplotypes has been found to possess a large 15 380 bp deletion beginning after nt 23 inside of Pina coding sequence in comparison with the wild type. Besides the obvious influence on grain texture, puroindoline gene plays a significant role on other aspects of wheat quality so that some Pina and Pinb alleles have significantly different quality characteristics, e.g. Pinb-D1b have slightly superior quality of steamed bread, pan bread and Chinese noodles to Pina-D1b. Gsp-1 gene tightly linking with Pina and Pinb possesses more haplotypes than puroindoline genes while has no significant effect on grain texture according to lots of reports so far. Pinb-2v genes with approximate 70% identity to Pinb gene at the DNA level have been found to possess four variants very recently that locate on 7A, 7B and 7D chromosome, respectively, which play a minor role in controlling grain texture. This study has further provided useful information on understanding the molecular basis of grain texture and Chinese wheat improvement.

Key words: grain texture')">grain texture, Pina gene, Pinb gene, haplotype, wheat quality