Identification of waxy mutants in T. aestivum and their use in a breeding program.

摘要

Waxy mutations in bread wheat derive from the loss of functionality of the granule-bound starch synthase I (GBSSI), the key enzyme in amylose synthesis; whose coding loci; Wx-Al; Wx-Dl and Wx-Bl occurr on the short arms of chromosome 7A; 7D and onthe long arm of chromosome 4A; respectively. Wheat lines carrying one or two GBSS null alleles produces starch with reduced amylose content and are designated "partial-waxy"; while the loss of all three GBSS isoforms gives rise to amylose-free starch;termed waxy. Waxy wheats may find usefiil application in the production of modified food starch and for the improvement of the shelf-life of baked products; moreover; they strongly influence Asian noodle quality. Until now; no spontaneous triple nullmutants have been found; the ones known being obtained by induced mutation or by crossing wheat lines with the proper combination of null alleles. The present study reports the results of a breeding program set up to develop waxy wheat lines adapted toItalian environments from partial-warp cultivars previously identified from a screening of Italian germplasm. The study was performed by colorimetric analysis; followed by electrophoretic fractionation of the GBSS isoforms and PCR analyses with specificprimers.