Barley HOMOCYSTEINE METHYLTRANSFERASE 2 confers drought tolerance by improving polyamine metabolism

作者：Cheng‐Wei Qiu, Yue Ma, Qingqing Wang, Manman Fu, Chengdao Li, Yizhou Wang, Feibo Wu · 发表于：PLANT PHYSIOLOGY · 年份：2023 · DOI：10.1093/plphys/kiad333 · 被引用次数：21 · 研究领域：Polyamine Metabolism and Applications、Cassava research and cyanide、Plant responses to water stress

Drought stress poses a serious threat to crop production worldwide. Genes encoding homocysteine methyltransferase (HMT) have been identified in some plant species in response to abiotic stress, but its molecular mechanism in plant drought tolerance remains unclear. Here, transcriptional profiling, evolutionary bioinformatics, and population genetics were conducted to obtain insight into the involvement of HvHMT2 from Tibetan wild barley (Hordeum vulgare ssp. agriocrithon) in drought tolerance. We then performed genetic transformation coupled with physio-biochemical dissection and comparative multiomics approaches to determine the function of this protein and the underlying mechanism of HvHMT2-mediated drought tolerance. HvHMT2 expression was strongly induced by drought stress in tolerant genotypes in a natural Tibetan wild barley population and contributed to drought tolerance through S-adenosylmethionine (SAM) metabolism. Overexpression of HvHMT2 promoted HMT synthesis and efficiency of the SAM cycle, leading to enhanced drought tolerance in barley through increased endogenous spermine and less oxidative damage and growth inhibition, thus improving water status and final yield. Disruption of HvHMT2 expression led to hypersensitivity under drought treatment. Application of exogenous spermine reduced accumulation of reactive oxygen species (ROS), which was increased by exogenous mitoguazone (inhibitor of spermine biosynthesis), consistent with the association of HvHMT2-mediate...