TbMYC4A Is a Candidate Gene Controlling the Blue Aleurone Trait in a Wheat- Triticum boeoticum Substitution Line

Xin Liu; Minghu Zhang; Xiaomei Jiang; Hui Li; Zhenjiao Jia; Ming Hao; Bo Jiang; Lin Huang; Shunzong Ning; Zhongwei Yuan; Xuejiao Chen; Xue Chen; Dengcai Liu; Baolong Liu; Lianquan Zhang

doi:10.3389/fpls.2021.762265

TbMYC4A Is a Candidate Gene Controlling the Blue Aleurone Trait in a Wheat- Triticum boeoticum Substitution Line

Front Plant Sci. 2021 Nov 5:12:762265. doi: 10.3389/fpls.2021.762265. eCollection 2021.

Authors

Xin Liu¹, Minghu Zhang¹, Xiaomei Jiang¹, Hui Li¹, Zhenjiao Jia¹, Ming Hao¹, Bo Jiang¹, Lin Huang^{1

2}, Shunzong Ning¹, Zhongwei Yuan¹, Xuejiao Chen¹, Xue Chen¹, Dengcai Liu^{1

2}, Baolong Liu^{3

4}, Lianquan Zhang^{1

2}

Affiliations

¹ Triticeae Research Institute, Sichuan Agricultural University, Chengdu, China.
² State Key Laboratory of Crop Gene Exploration and Utilization in Southwest China, Sichuan Agricultural University, Chengdu, China.
³ Qinghai Province Key Laboratory of Crop Molecular Breeding, Xining, China.
⁴ Key Laboratory of Adaptation and Evolution of Plateau Biota (AEPB), Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining, China.

Abstract

Triticum boeoticum Boiss (A^bA^b, 2n = 2x = 14) is one of the sources of the blue grain trait controlled by blue aleurone layer 2 (Ba2). However, the underlying genes have not been cloned. In this study, a transcriptomic comparison between a blue-grained wheat-T. boeoticum substitution line and its wheat parent identified 41 unigenes related to anthocyanin biosynthesis and 29 unigenes related to transport. The bHLH transcription factor gene TbMYC4A showed a higher expression level in the blue-grained substitution line. TbMYC4A contained the three characteristic bHLH transcription factor domains (bHLH-MYC_N, HLH and ACT-like) and clustered with genes identified from other wheat lines with the blue grain trait derived from other Triticeae species. TbMYC4A overexpression confirmed that it was a functional bHLH transcription factor. The analysis of a TbMYC4A-specific marker showed that the gene was also present in T. boeoticum and T. monococcum with blue aleurone but absent in other Triticeae materials with white aleurone. These results indicate that TbMYC4A is a candidate gene of Ba2 controlling the blue aleurone trait. The isolation of TbMYC4A is helpful for further clarifying the genetic mechanism of the blue aleurone trait and is of great significance for breeding blue-grained wheat varieties.

Keywords: TbMYC4A; Triticum boeoticum; anthocyanin biosynthesis; blue aleurone; transcriptome analysis.