Development of soft kernel durum wheat

Abstract

Kernel texture (grain hardness) is a fundamental and determining factor related to wheat (Triticum spp.) milling, baking and flour utilization. There are three kernel texture classes in wheat: soft and hard hexaploid (T. aestivum), and very hard durum (T. turgidum subsp. durum). The genetic basis for these three classes lies with the Puroindoline genes. Phenotypically, the easiest means of quantifying kernel texture is with the Single Kernel Characterization System (SKCS), although other means are valid and can provide fundamental material properties. Typical SKCS values for soft wheat would be around 25 and for durum wheat≥80. Soft kernel durum wheat was created via homeologous recombination using the ph1b mutation, which facilitated the transfer of ca. 28 Mbp of 5DS that replaced ca. 21 Mbp of 5BS. The 5DS translocation contained a complete and intact Hardness locus and both Puroindoline genes. Expression of the Puroindoline genes in durum grain resulted in kernel texture and flour milling characteristics nearly identical to that of soft wheat, with high yields of break and straight-grade flours, which had small particle size and low starch damage. Dough water absorption was markedly reduced compared to durum flour and semolina. Dough strength was essentially unchanged and reflected the inherent gluten properties of the durum background. Pasta quality was essentially equal-to-or-better than pasta made from semolina. Agronomically, soft durum germplasm showed good potential with moderate grain yield and resistance to a number of fungal pathogens and insects. Future breeding efforts will no doubt further improve the quality and competitiveness of soft durum cultivars.

Keywords

soft durum wheat / grain hardness / Puroindolines / milling / baking / pasta / noodles

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Acknowledgements

The assistance of Stacey Sykes, Shawna Vogl, and the entire staff of the Western Wheat Quality Laboratory, especially Doug Engle, Gail Peden, Mary Baldridge, Bill Kelley, Mishelle Lenssen and Eric Wegner are gratefully acknowledged. Numerous collaborators made contributions to the development and evaluations of soft durum; please note the co-authors cited in the References. Of particular thanks, the contributions of Leonard Joppa, Alecia Kiszonas, Marco Simeone, Domenico Lafiandra, Jessica Murray, Jeff Boehm Jr., and Maria Itria Ibba are warmly acknowledged.

Compliance with ethics guidelines

Craig F. Morris declares that he has no conflict of interest; as a co-inventor of soft durum wheat, he receives some licensing royalties from USDA.

This article is a review and does not contain any studies with human or animal subjects performed by the author.

RIGHTS & PERMISSIONS

The Author(s) 2019. Published by Higher Education Press. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0)