Mapping of Traits Adaptive to the U.S. Southern and Central Great Plains in a ‘Tam 204’/’Iba’ Population and Developing Superior Pre-Harvest Sprouting Tolerant Hard White Winter Wheat Version of ‘Tam 114’ Using Crispr-Cas9 Gene Editing

Abstract

The development of superior cultivars with outstanding agronomical performance, enhanced pest resistance, or special traits could be facilitated with the use of molecular breeding techniques. To achieve this, the Texas A&M wheat breeding and genetics program have developed the bi-parental population derived from ‘TAM 204’ and ‘Iba’ to identify genomic regions with favorable alleles for pest resistance and agronomical traits. The 221 recombinant inbred lines of this population were screened for Greenbug and Hessian fly under greenhouse conditions as well as grown in 11 environments across Texas. Also, a second project to develop a white grain isoline of ‘TAM 114’ was established. In the first study, the accuracy of the linkage groups was validated by mapping highly heritable traits. Quantitative Trait Loci (QTL) associated with Hessian fly were detected on chromosome 1A and 3B. A major QTL for Greenbug resistance was identified in chromosome 7D. For agronomical traits, a total of 86 QTL were identified, for which 38 were consistent. For grain yield, ten consistent QTL were identified on chromosomes 2A, 2B, 2D, 3D, 5A and 6A, with the QTL located at 29 Mb on 2D having a high additive effect. For plant height, 11 QTL were identified in chromosomes 2A, 2B, 4A, 4B, 4D, 5A, 6A and 6D, whereas for days to heading, four consistent QTL were found in chromosomes 2B, 2D and 5B. With regards to the test weight and thousand kernel weight traits, eight and three consistent QTL were detected, respectively. For the second project, two highly specific sgRNA for multiplex editing of the Tamyb-10 homeologous genes were designed and their cleaved efficiency was validated in vitro. The Immature embryo transformation was performed using biolistics. A total of 63 plants were regenerated out of 266 immature embryos, demonstrating that TAM 114 has a modest regeneration capability. Genotyping of the targeted regions using Sanger sequencing was performed, but no results were obtained. Additionally, an alternative tissue transformation protocol using mature embryos was tested. This second protocol significantly reduced the time and labor associated with tissue culture; however, the transformation efficiency of both protocols has not been tested yet.