Identification Of A Novel Wx-A1 Null Allele In Durum Wheat (Triticum turgidum ssp. durum).

VANZETTI L.; PFLUGER L.; BAINOTTI C.; JENSEN C.; HELGUERA M.

San Diego. EEUU

Conferencia; XVII Plant and Animal Genome; 2009

Starch is a polymer composed of two types of glucose carbohydrates: amylose and amylopectin. The GBSSI or waxy proteins, are the enzymes responsible for amylose synthesis in storage tissues of cereals. In durum wheat (Triticum turgidum ssp. durum) two genes encoding GBSSI proteins have been described, Wx-A1, located on chromosome 7AS, and Wx-B1 on 4AL. Presence of waxy null allele/s reduces significantly amylose content in starch affecting gelatinization, pasting and gelation among other properties of starch. This work describes a novel Wx-A1 null allele detected in one cultivar and two breeding lines from a collection of 48 durum wheats from Argentina. Two different sources of evidence were used in the present study: (1) SDS-PAGE of GBSSI proteins. In this analysis the three lines carrying the putative Wx-A1 null allele did not show the band associated to the Wx-A1 GBSSI protein. (2) Sequence analysis.  Wx-A1 partial sequence obtained from the three lines showed a 1-bp deletion in exon 6 that produced a frameship and a premature stop codon. Additionally, a PCR-RFLP marker suitable to detect this mutation is described. This molecular tool will facilitate the development of durum wheat isolines to study the effect of the Wx-A1 null allele described here, considering different aspects of durum wheat quality