DisplayTitle

Granule Bound Starch Synthase I (GBSSI) Gene Effects Related to Soft Wheat Flour/Starch Characteristics and Properties

¹Department of Food Science and Technology, University of Nebraska, Lincoln, NE 68583-0919. ²Department of Food Science and Toxicology, University of Idaho, P.O. Box 442312, Moscow, ID 83844. ³USDA-ARS Soft Wheat Quality Laboratory, Wooster, OH 44691. ⁴Corresponding author. Phone: 208-885-4661. Fax: 208-885-2567. E-mail: huberk@uidaho.edu

Eight soft spring wheat (Triticum aestivum L.) genotypes representing the four granule bound starch synthase I (GBSSI) classes were evaluated with respect to flour/starch characteristics and pasting behaviors. Native starch was isolated from genotype straight-grade flours (94.8–98.1% of starch recovered) to approximate the starch populations of the parent flours. As anticipated, amylose characteristics varied among the genotypes according to GBSSI class and accounted for the primary compositional difference between genotypes. Total (TAM), apparent (AAM), and lipid-complexed (LAM) amylose contents ranged from 1.0–25.5 g, 0.7–20.4 g, and 0.3–5.6 g/100 g of native starch, respectively, and gradually decreased with the progressive loss of active Wx alleles. In addition, genotype flour total starch (FTS) and A-type starch granule contents, which ranged from 81.7–87.6 g/100 g of flour (db) and 61.6–76.8 g/100 g of native starch (db), respectively, generally decreased with an increase in waxy character in parallel with amylose characteristics, as likely secondary effects of Wx gene dosage. Though amylose characteristics predominantly accounted for the majority of genotype flour pasting properties, FTS content and ratios of A- to B-type granules also exhibited significant influence. Thus, loss of one or more Wx genes appeared to induce measurable secondary effects on starch characteristics and properties.