Xin Lu , Yuhong Lei, Zhennan Xu, Zixiang Cheng, Meng Liu, Yuxin Tai, Xiaohua Han, Zhuanfang Hao, Mingshun Li, Degui Zhang, Hongjun Yong, Jienan Han, Zhenhua Wang, Wenxue Li, Jianfeng Weng, Zhiqiang Zhou, Xinhai Li

Molecular Plant; 2025; IF:17.1

DOI: 10.1016/j.molp.2025.04.008

Abstract

Efforts to improve the methionine (Met) content in maize kernels are of key importance to the animal feed industry. In this study, a panel consisting of 348 diverse inbred maize lines was leveraged to explore the genetic and molecular mechanisms that govern kernel Met levels. A genome-wide association study ultimately identified the deSUMOylating isopeptidase gene ZmDeSI2. In subsequent experiments, ZmDeSI2 was confirmed to directly reduce the SUMOylation and accumulation of the sulfite reductase ZmSIR, ultimately repressing Met accumulation. Natural variants identified in the ZmDeSI2 promoter region were found to serve as key determinants of the expression of this gene, with these effects predominantly being attributable to the absence of a ZmWRKY105 transcription factor binding site in ZmDeSI2^Hap2 lines. The artificially selected elite ZmDeSI2^Hap2 haplotype was associated with a 1.36-fold increase in Met levels in the kernels of modified near-isogenic lines generated through marker-assisted breeding based on a presence-absence variation in the ZmDeSI2 promoter. Together, these results provide new insights into the molecular processes that control Met biosynthesis while also highlighting an elite natural variant suitable for application in maize breeding efforts focused on Met biofortification.