Fine mapping of the reduced height gene Rht22 in tetraploid wheat landrace Jianyangailanmai (Triticum turgidum L.)

https://link.springer.com/article/10.1007/s00122-022-04207-8

Theoretical and Applied Genetics，135，3643–3660（2022）

Chao Wang,Yunjing Bao,Qin Yao,Dan Long,Xue Xiao,Xing Fan,Houyang Kang,Jian Zeng,Lina Sha,Haiqin Zhang,Dandan Wu,Yonghong Zhou,Qiang Zhou，Yi Wang&Yiran Cheng

Key message

Rht22was fine mapped in the interval of 0.53–1.48 Mb on 7AS, which reduces cell number of internode to cause semi-dwarfism in Jianyangailanmai.

Abstract

As a valuable germplasm resource for wheat genetic improvement, tetraploid wheat has several reduced height (Rht) and enhanced harvest index genes.Rht22, discovered in Jianyangailanmai (JAM,Triticum turgidumL., 2n = 4x = 28, AABB), significantly increases the spikelet number per spike, but its accurate chromosomal position is still unknown. In this study, a high-density genetic map was constructed using specific-length amplified fragment sequencing in an F7RIL_DJ population, which was derived from a cross between dwarf Polish wheat (T. polonicumL., 2n = 4x = 28, AABB) and JAM. Two plant height loci,Qph.sicau-4BandQph.sicau-7A, were mapped on chromosomes 4BS and 7AS, respectively.Qph.sicau-7Awas mapped to the 0.33-4.46 Mb interval on 7AS and likely represents the candidate region ofRht22. Fine mapping confirmed and narrowedRht22on chromosome arm 7AS betweenXbag295.s53andXb295.191in three different populations. The physical region ranged from 0.53 to 1.48 Mb and included 18 candidate genes. Transcriptome analysis of two pairs of near-isogenic lines revealed that 135 differentially expressed genes (DEGs) were associated with semi-dwarfism. Of these, the expression of 83 annotated DEGs involved in hormones synthesis and signal transduction, cell wall composition, DNA replication, microtubule and phragmoplast arrays was significantly down-regulated in the semi-dwarf line. Therefore,Rht22causes semi-dwarfism in JAM by disrupting these cellular processes, which impairs cell proliferation and reduces internode cell number.