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Effects on Soft Wheat (Triticum aestivum L.) Quality of Increased Puroindoline Dosage¹

¹This research was supported by USDA-ARS National Research Initiative Competitive Grants Program grant 2004-01141 and by the Montana Agricultural Experiment Station. ²Department of Plant Science and Plant Pathology, Montana State University, 119 Plant BioScience Building, Bozeman, MT 59717-3150. ³WestBred LLC, 8111 Timberline Drive, Bozeman, MT 59718-8184. ⁴Corresponding author. Phone: 406-994-7877. Fax: 406-994-7600. E-mail: mgiroux@montana.edu

Wheat (Triticum aestivum L.) grain hardness affects many end-product quality traits and is controlled primarily by the Hardness (Ha) locus that contains the Puroindoline a and b genes (Pina and Pinb, respectively). All soft hexaploid wheats carry the same Pin alleles, and hard wheats carry a mutation in Pina or Pinb. Here we test the heritability and milling and flour quality effects of increased Pin dosage in soft wheat. Previous experiments have suggested that grain softness can be enhanced by increasing Ha locus dosage through chromosome substitutions. Segregation data from a cross of cultivar Chinese Spring substitution lines with six doses of the Ha locus to the locally adapted soft wheat cultivar Vanna indicate that the substituted B genome Ha locus was not transmitted and that the A genome Ha locus was transmitted normally. Genotypes with the added Pins on the A genome produced seeds that were 7.4 hardness units softer. These softer double Ha genotypes were lower in flour yields, but produced flour with lower ash content, reduced starch damage, and smaller mean particle size. Soft wheats with increased Ha dosage may be useful in improving soft wheat quality through its effects on particle size and starch damage.