ARS | Publication request: Discovery of a new puroindole b gene in wheat

Submitted to: International Wheat Quality Conference
Publication Type: Proceedings
Publication Acceptance Date: June 3, 2009
Publication Date: March 10, 2010
Citation: Morris, C.F., Beecher, B.S., Chen, F. 2010. Discovery of a new puroindole b gene in wheat. International Wheat Quality Conference.

Interpretive Summary: Puroindoline proteins are present throughout the Triticeae tribe of the Poaceae (Gramineae), including wheat, rye, barley, and the wild relatives of wheat. In wheat, puroindolines exist as two expressed genes, Puroindoine a and Puroindoline b, on the end of the short arm of chromosome 5 (5DS). An exception to this situation lies with the tetraploid (AABB) wheats (T. turgidum), which includes cultivated durum. The presence of Puroindoine a D1a (Pina D1a) and Puroindoline b D1a (Pinb D1a) are associated with soft kernel texture in soft wheat varieties. Recently Wilkinson et al. (2008) reported three new puroindoline gene-like sequences in hexaploid wheat. The genes shared close homology with Pinb and hence were designated Pinb 'variants.' This publication provides evidence to show that the three variants reported by Wilkinson et al. (2008) exist as a homoeologous series, wherein variant 1 (Pinb 2v1) resides on the short arm of chromosome 7D (7DS), variant 2 (Pinb 2v2) resides on 7BL, and variant 3 resides on 7B; variant 3 may not be allelic to variant 2. Lastly, this publication reports the discovery of a fourth variant (Pinb 2v4) which resides on 7AL.

Technical Abstract: Wilkinson and co-workers (2008) reported the existence of three new variant forms of puroindoline b. Termed simply variants 1, 2 and 3, these genes were purported to be encoded by the same Pinb-2 locus on chromosome 7A. In our research, we examined a total of 5 wheat cultivars, 38 ditelosomic lines, six group 7 nullisomic/tetrosomic lines of Chinese Spring, and 20 disomic substitution lines of Chinese Spring and Cheyenne. During the course of this work we discovered the existence of a fourth variant (variant 4) with a sequence suggesting similarity to the previous three. Preliminary results indicate that variant 1 and 4 are present in possibly all hexaploid wheats, whereas Chinese Spring additionally possesses variant 2, and Cheyenne variant 3. Results also indicate that these Pinb-2 variant loci are located on homoeologous chromosomes 7A, 7B and 7D (Pinb-A2, Pinb-B2 and Pinb-D2). An up-to-date report of research progress will be presented at the conference.