Occurrence of 'super soft' wheat kernel texture in hexaploid and tetraploid wheats

Authors: Morris, Craig; ORENDAY-ORTIZ, JOSE - Washington State University; IBBA, MARIA ITRIA - Washington State University; Kiszonas, Alecia; Delwiche, Stephen - Steve; Wilson, Jeff

Submitted to: American Association of Cereal Chemists Meetings
Publication Type: Abstract Only
Publication Acceptance Date: 5/24/2018
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Wheat kernel texture is a key trait that governs milling performance, flour starch damage, flour particle size, flour hydration properties, and baking quality. Kernel texture is commonly measured using the Perten Single Kernel Characterization System (SKCS). The SKCS returns texture values (Hardness Index, HI) of ~25 for soft hexaploid wheat (Triticum aestivum), ~55-70 for hard hexaploid wheat, and ~75-90 for durum wheat (T. turgidum subsp. durum). The primary basis for kernel texture is the puroindoline genes at the Hardness locus. When the wild-type puroindoline genes are naturally present in hexaploid wheat or introduced into durum wheat, the texture is soft. However, we have observed SKCS phenotypes considerably softer than those commonly encountered, as low as -9 (hexaploid) and -2 (tetraploid) in two genetically defined populations. The hexaploid population was a recombinant inbred line (RIL) set from cv. Alpowa soft white spring by a back-cross-2 (BC2) super soft Alpowa derivative (BC2SS163); the durum population was a RIL set from cv. Creso durum by a Langdon durum translocation line carrying the Hardness locus on ca. 28 Mbp of chromosome 5DS. Genotyping by sequencing (GBS) identified 193 significant Single Nucleotide Polymorphic markers at two Quantitative Trait Loci, the more prominent one was associated with a major locus on chromosome 1B in hexaploid wheat. In durum wheat, significant dominant markers identified loci on 6AS and 3AL. Cylinders of defined geometry were prepared from kernel endosperm and subjected to compression testing. SKCS HI for the tested hexaploid samples ranged from -9 to 25, whereas the tetraploids ranged from 1 to 26; Creso durum was 78. Results indicated that for the hexaploid wheats, SKCS HI was positively correlated with maximum stress (r=0.72), Young’s Modulus (r=0.68), and work at maximum stress (r=0.55). For the tetraploids, SKCS HI was positively correlated with maximum stress (r=0.86), Young’s Modulus (r=0.85), and work at maximum stress (r=0.74). Among the hexaploid wheat lines, HI was correlated with percentage B-type starch granules (<10 um) at r=-0.61. Whereas ‘normal soft’ flour had 2.0% damaged starch, the super soft hexaploid wheat flours ranged down to a low of 1.2%. We continue to resolve the genetic basis and commercial value of this ‘super soft’ phenotype.