期刊
JOURNAL OF EXPERIMENTAL BOTANY
卷 68, 期 5, 页码 1213-1224出版社
OXFORD UNIV PRESS
DOI: 10.1093/jxb/erw496
关键词
Brassica rapa; cold acclimation; DNA methylation; heat tolerance; organic acids; photosynthesis
资金
- National Natural Science Foundation of China [31330067, 31301782]
- Natural Science Foundation of Jiangsu Province of China [BK20130673]
- China Postdoctoral Science Special Foundation [2015T80561]
- China Postdoctoral Science Foundation [2014M550294]
- Opening Foundation of State Key Laboratory of Crop Genetics and Germplasm Enhancement [ZW2014006]
Epigenetic modifications are implicated in plant adaptations to abiotic stresses. Exposure of plants to one stress can induce resistance to other stresses, a process termed cross-adaptation, which is not well understood. In this study, we aimed to unravel the epigenetic basis of elevated heat-tolerance in cold-acclimated Brassica rapa by conducting a genome-wide DNA methylation analysis of leaves from control (CK) and cold-acclimated (CA) plants. We found that both methylation and demethylation occurred during cold acclimation. Two significantly altered pathways, malate dehydrogenase activity and carbon fixation, and 1562 differentially methylated genes, including BramMDH1, BraKAT2, BraSHM4, and Bra4CL2, were identified in CA plants. Genetic validation and treatment of B. rapa with (Aza) suggested that promoter demethylation of four candidate genes increased their transcriptional activities. Physiological analysis suggested that elevated heat-tolerance and high growth rate were closely related to increases in organic acids and photosynthesis, respectively. Functional analyses demonstrated that the candidate gene BramMDH1 (mMDH: mitochondrial malate dehydrogenase) directly enhances organic acids and photosynthesis to increase heat-tolerance and growth rate in Arabidopsis. However, Aza-treated B. rapa, which also has elevated BramMDH1 levels, did not exhibit enhanced heat-tolerance. We therefore suggest that DNA demethylation alone is not sufficient to increase heat-tolerance. This study demonstrates that altered DNA methylation contributes to cross-adaptation.
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