Submitted to: Wheat: Genetics, Crops, and Food Production
Publication Type: Book / chapter
Publication Acceptance Date: 9/18/2010
Publication Date: N/A
Citation: Interpretive Summary: Puroindoline genes in common wheat make kernel texture of the endosperm soft. When the puroindoline genes are mutated or deleted the kernels of common wheat become harder. It has been determined that puroindolines a and b play a very important role in the quality of wheat. Recently a new group of puroindoline b genes have been discovered, and this manuscript details coding and flanking sequence for three new Pinb variants. In addition to this new group of Pinb variants, a Pinb variant in durum wheat is reported in this manuscript. The study of this gene polymorphism and the discovery of some novel puroindoline variants will be helpful in understanding the molecular and genetic basis of kernel hardness in the future.
Technical Abstract: The puroindoline genes (Pina and Pinb) are the functional components of common wheat (Triticum aestivum L.) grain hardness locus that are responsible for kernel texture. Puroindoline a and b proteins soften the endosperm of wheat kernels. When the underlying puroindoline genes are altered by mutation or are deleted, kernels become harder. Thus puroindoline a and b (Pina and Pinb) play an important role in wheat quality and utilization. Recently, additional Pinb genes have been reported. In the present report, we provide corroborating coding and additional 5’ and 3’ flanking sequence for three Pinb variants: Pinb 2v1, Pinb 2v2, and Pinb 2v3. Additionally, two new Pinb variants, Pinb 2v4 in bread wheat and Pinb-2v5 in durum wheat, are reported. Four of five variants were physically mapped using Chinese Spring (CS) diteolosomics, nullisomic-tetrasomics, CS-Cheyenne disomic substitution lines and CS-Langdon substitution lines. Results place Pinb 2v1 on 7DL, Pinb 2v2 on 7BL, Pinb 2v3 on 7B, and Pinb 2v4 on 7AL. Pinb 2v4 was present in all examined common and durum wheat cultivars including Chinese Spring, Cheyenne, Recital, Wichita and Winsome, and Pinb-2v1 was only present in all examined common wheat cultivars but absent in all durum wheat cultivar surveyed. Pinb 2v2 was present in small part of common and durum wheat cultivars including Chinese Spring and Recital. Pinb 2v3 was present in the most surveyed common and durum wheat cultivars including Cheyenne, Wichita and Winsome. Pinb-2v5 was only found in durum wheat cultivar Langdon until now. Interestingly, Pinb-2v2 and Pinb-2v3 are possibly allelic due to their reciprocal presence in different cultivars. These physically mapping results are not wholly consistent with prior research and additional studies will be required to reconcile discrepancies. In addition, further sequencing results indicated that, in comparison with Pinb-2v3 sequence (AM99733 and GQ496618 with one base-pair modification of G to T at 6th position, designated Pinb-2v3a) in bread wheat cultivars Witchta, the coding region of Pinb-2v3 in 12 durum wheat cultivars had a single nucleotide change from T to C at the 312th position, resulting in corresponding amino acid change from valine to alanine at the 104th position, and this new allele was designed as Pinb-2v3b. Study of puroindoline b-2 gene polymorphism in common and durum wheat germplasm and discoveries of two novel puroindoline b-2 variant and a new Pinb-2v3 allele could provide useful information for further understanding molecular and genetic basis of kernel hardness and illustrating gene duplication events in wheat.