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Characterization of a Unique “Super Soft” Kernel Trait in Wheat

¹USDA-ARS Western Wheat Quality Laboratory, Washington State University, Pullman, WA 99164-6394. Mention of trademark or proprietary products does not constitute a guarantee or warranty by the U.S. Department of Agriculture and does not imply its approval to the exclusion of other products that may also be suitable. ²Corresponding author. USDA-ARS Western Wheat Quality Laboratory, E-202 Food Science and Human Nutrition Facility East, P.O. Box 646394, Washington State University, Pullman, WA 99164. Phone: (509) 335-4062. Fax: (509) 335-8573. E-mail: morrisc@wsu.edu ³Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, MN 55108. ⁴Retired from Department of Food Science and Human Nutrition, Washington State University, Pullman, WA 99164; assigned to the Western Wheat Quality Laboratory. ⁵USDA-ARS Wheat Genetics, Quality, Physiology, and Disease Unit, Washington State University, Pullman, WA 99164. ⁶Retired from USDA-ARS Wheat Genetics, Quality, Physiology, and Disease Unit, Washington State University, Pullman, WA 99164. ⁷Department of Crop and Soil Sciences, Washington State University, Pullman, WA 99164; assigned to the Western Wheat Quality Laboratory.

Kernel texture in wheat (Triticum sp.) is central to end-use quality and utilization. Here we report the discovery of a novel soft kernel trait in soft white winter wheat (T. aestivum L.). Two heritable kernel phenotypes were selected among F₃-derived sibs, hereafter designated “normal soft” (wild-type) and “super soft.” Normal soft lines exhibited single kernel characterization system (SKCS) hardness index (HI) values typical of soft wheat (HI ≈ 20), whereas the super soft lines were unusually soft (HI ≈ 5). Under some environments, individual super soft lines exhibited HI values as low as HI = –4. The super soft trait was manifested in reduced SKCS kernel texture and higher break flour yields, with some increase in sodium carbonate SRC (solvent retention capacity) values and sponge cake volumes. Straight-grade flour yield, flour ash, milling score, and cookie diameter were largely unaffected. With the possible exception of the sodium carbonate SRC values, we observed no indication that the super soft trait conferred any negative aspects to commercial soft wheat quality. As such, the super soft trait may provide wheat breeders with new opportunities to modify the end-use quality of wheat.