Sequence diversity of the puroindoline a and b genes in Aegilops tawsc/m-relationship tokernel texture in wheat

摘要

Puroindoline a and b (PinA, PinB) constitute the molecular-genetic basis of the Hardness locus in wheat (Triticum aestivum L.). For each, a single functional sequence is present in Chinese Spring and all soft wheats. All hard wheats have a defect in either PinA or PinB. In PinA, the defect results in the complete loss of expression. In PinB, six Single Nucleotide Polymorphisms (SNPs) result in three altered amino acids and three STOP codons. The soft PinA and PinB genes were contributed by Aegilops tauschii, the D-genome donor of wheat. Since previous studies found puroindoline sequence polymorphisms in Ae. tauschii, we undertook two surveys: one of Ae. tauschii and the second of synthetic T. durum X Ae. tauschii hexaploids produced at CIMMYT. In Ae. tauschii, seven unique gene sequences were identified among 50 accessions. Thirteen accessions possessed the same PinA and PinB sequences as soft hexaploid wheat. All were categorized as belonging to the taushcii subspecies (vs. the strangulata subsp.). Since the technological means is not available to easily measure kernel texture in Ae. tauschii, we obtained synthetic hexaploids with the aim of correlating puroindoline gene sequence and kernel texture. Classification of lines based on durum and Ae.tauschii parents showed significant differences between mean kernel texture.