Data_Sheet_3_Epigenetic Regulation of Plant Tolerance to Salt Stress by Histone Acetyltransferase GsMYST1 From Wild Soybean.PDF

Salt stress is one of the most devastating environmental factors threatening soybean growth and yield. However, the molecular link between salt stress and epigenetics has not been well-elucidated in soybean. In this study, from the wild soybean cDNA library, we isolated a GsSnRK1 kinase interacting protein (GsMSTY1) which is phylogenetically homologous with histone acetyltransferase MYST family with unknown function. GsMSTY1 gene is dominantly expressed in wild soybean roots and is highly responsive to abiotic stresses. GsMYST1 was able to be phosphorylated at the Ser44 site by GsSnRK1 and demonstrated in vivo acetyltransferase activity in transgenic soybean roots revealed by an anti-H4ace antibody. A transcription factor protein GsNAC83 was identified to interact with both GsMYST1 and GsSnRK1, and GsNAC83 could recruit the GsMYST1-GsSnRK1 module to COR15B gene promoter determined by ChIP-qPCR assay. To dissect the molecular functions of this ternary complex, we treated the transgenic soybean roots with salt stress and found that the stress could activate GsSnRK1, and the activated GsSnRK1 subsequently phosphorylated GsMYST1 to enhance its acetyltransferase activity which may epigenetically promote the target gene expression. To explore the physiological functions, we coexpressed GsSnRK1 and GsMYST1 genes in soybean hairy roots and found that only GsSnRK1(wt)/GsMYST1(wt) but not the mutant genes could promote soybean resistance to salt stress, implicating that phosphorylation of GsMYST1 is required for it to acetylate histone H4 on the target genes to upregulate expression of the stress-related genes. Our data shed new light on the functions of the GsSnRK1-GsMYST1-GsNAC83 module and its regulatory mechanism on plant tolerance to abiotic stresses.

盐胁迫是威胁大豆生长与产量的最具破坏性的环境因子之一，然而目前大豆中盐胁迫与表观遗传学之间的分子关联尚未得到充分阐明。本研究从野生大豆cDNA文库（cDNA library）中分离得到一个与GsSnRK1激酶互作的蛋白（GsMSTY1），该蛋白与功能未知的组蛋白乙酰转移酶MYST家族（histone acetyltransferase MYST family）在系统发育上具有同源性。GsMSTY1基因在野生大豆根系中优势表达，且对多种非生物胁迫响应强烈。GsMYST1可被GsSnRK1在Ser44位点磷酸化，通过抗H4乙酰化抗体（anti-H4ace antibody）检测证实，其在转基因大豆根系中具有体内乙酰转移酶活性。研究鉴定到转录因子GsNAC83可同时与GsMYST1和GsSnRK1互作，且通过染色质免疫共沉淀定量PCR（ChIP-qPCR）实验证实，GsNAC83可将GsMYST1-GsSnRK1复合体招募至COR15B基因启动子区域。为解析该三元复合体的分子功能，我们对转基因大豆根系施加盐胁迫处理，发现胁迫可激活GsSnRK1，活化的GsSnRK1随后磷酸化GsMYST1以增强其乙酰转移酶活性，进而可能通过表观遗传机制促进靶基因的表达。为探究其生理功能，我们在大豆毛状根中共表达GsSnRK1与GsMYST1基因，结果显示仅野生型GsSnRK1（GsSnRK1(wt)）与野生型GsMYST1（GsMYST1(wt)）可提升大豆的耐盐性，而突变体基因则无此效果，这表明GsMYST1的磷酸化是其在靶基因位点乙酰化组蛋白H4、上调胁迫相关基因表达的必要条件。本研究为GsSnRK1-GsMYST1-GsNAC83复合体的功能及其调控植物耐非生物胁迫的分子机制提供了新的见解。