Identification of the Solid Stem Suppressor Gene Su-TdDof in Synthetic Hexaploid Wheat Syn-SAU-117

Hui Li，Xin Liu，Junqing Zhang，Longyu Chen，Minghu Zhang，Yongping Miao，Pan Ma，Ming Hao，Bo Jiang，Shunzong Ning，Lin Huang，Zhongwei Yuan

Lodging is one of the most important factors affecting the high and stable yield of wheat worldwide. Solid-stemmed wheat has higher stem strength and lodging resistance than hollow-stemmed wheat does. There are many solid-stemmed varieties, landraces, and old varieties of durum wheat. However, the transfer of solid stem genes from durum wheat is suppressed by a suppressor gene located on chromosome 3D in common wheat, and only hollow-stemmed lines have been created. However, synthetic hexaploid wheat can serve as a bridge for transferring solid stem genes from tetraploid wheat to common wheat. In this study, the F1, F2, and F2:3generations of a cross between solid-stemmed Syn-SAU-119 and semisolid-stemmed Syn-SAU-117 were developed. A single dominant gene, which was tentatively designatedSu-TdDofand suppresses stem solidity, was identified in synthetic hexaploid wheat Syn-SAU-117 by using genetic analysis. By using bulked segregant RNA-seq (BSR-seq) analysis,Su-TdDofwas mapped to chromosome 7DS and flanked by markersKASP-669andKASP-1055within a 4.53 cM genetic interval corresponding to 3.86 Mb and 2.29 Mb physical regions in the Chinese Spring (IWGSC RefSeq v1.1) andAe. tauschii(AL8/78 v4.0) genomes, respectively, in which three genes related to solid stem development were annotated.Su-TdDofdiffered from a previously reported solid stem suppressor gene based on its origin and position.Su-TdDofwould provide a valuable example for research on the suppression phenomenon. The flanking markers developed in this study might be useful for screeningAe. tauschiiaccessions with no suppressor gene (Su-TdDof) to develop more synthetic hexaploid wheat lines for the breeding of lodging resistance in wheat and further cloning the suppressor geneSu-TdDof.