|Kumar, Neeraj - Washington State University|
|Ibba, Maria Itria - Washington State University|
|Orenday-ortiz, Jose - Washington State University|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 4/8/2019
Publication Date: N/A
Technical Abstract: Kernel texture in wheat is an essential aspect of flour quality and utilization. In general terms, there are three kernel texture classes that follow the presence, absence, and haplotype of the Hardness locus, which is comprised of the puroindoline a and b genes/proteins (Pina and Pinb). Wild type Pina and Pinb produce soft endosperm texture, with Single Kernel Characterization System (SKCS) phenotypes of ~25-30. However, a novel "super soft" kernel phenotype has been observed in both Triticum aestivum and T. turgidum subsp. durum. This phenotype is characterized by SKCS hardness index (HI) values as low as -9. The origin of this super soft kernel phenotype transcends species; its cause is unknown. The original observation of super soft phenotype was among a small set of F5-derived sibs of soft white winter club wheat with the pedigree WA7437/WA7665. These ‘WA’ breeding lines were obtained from the USDA, but neither exhibited the super soft phenotype. The super soft sib line SS163 was crossed to the soft white spring wheat cultivar Alpowa. Spring progeny were selected and subsequently a back-cross-2 (Alpowa recurrent parent) derivative (‘BC2SS163’) was isolated. BC2SS163 was crossed to Alpowa and F3, F4, and F5 RIL populations were advanced by single seed descent. Composite interval mapping with 90K chip SNP markers produced four QTL with PVE (percent variance explained) of 18% (1BS), 13% (4BS), 11% (5AL), and 16% (7AS). In all these lines Ha was present in its wild-type haplotype. Subsequently, we conducted QTL mapping using the F6 RIL population and developed two molecular markers that explained PVE of 35.7% and 9.3%. Independently, a super soft phenotype was observed in durum wheat. An F6 RIL population was developed from the durum cultivar ‘Creso’ and a soft homoeologous recombinant line. GBS was performed on 426 RILs and identified major QTL on 3AL and 6AS; each locus contributed about 6 SKCS HI units (PVE 9% and 11%, respectively). The combined 3AL and 6AS haplotype produced a SKCS additive effect of 12 HI. A subset of these lines was analyzed through genomic in situ hybridization and scanning electron microscopy. The super soft durum lines did not differ from normal soft lines for either chromosome structure or endosperm morphology. Overall, results have advanced the understanding of the genetic inheritance and endosperm morphology associated with the super soft kernel phenotype. Current studies continue to identify the genetic basis and mechanism of the super soft trait.