DNA甲基化参与蓖麻盐胁迫“记忆”形成的分子机理研究

	DNA甲基化参与蓖麻盐胁迫“记忆”形成的分子机理研究
	李仕金
导师	张石宝，刘爱忠
关键词	盐胁迫，胁迫“记忆”，“记忆”基因，DNA甲基化，分子机制 salt stress, stress memory, priming, memory gene, DNA methylation, molecular mechanism
摘要	胁迫“记忆”是植物在经历较温和的胁迫之后，获得对后续胁迫更强耐受能力的现象。盐胁迫已成为影响农作物生长发育、产量和品质的一个重要因素，严重制约了农业可持续发展。研究表明，DNA甲基化在植物胁迫“记忆”的形成和维持过程中起到了重要作用。但DNA甲基化变异在盐胁迫“记忆”中的作用仍有待进一步阐明。我们利用蓖麻盐敏感品种为研究对象，采用转录组测序和全基因组DNA甲基化测序等方法，探索DNA甲基化调控蓖麻盐胁迫“记忆”形成的分子机理。研究发现，蓖麻幼苗经过低盐（75 mM NaCl）胁迫锻炼（priming）之后，明显提高了在高盐胁迫下的耐盐性，在生理上表现为经过锻炼的幼苗比未经锻炼的幼苗在高盐胁迫下积累更少的Na+和H2O2含量。我们在叶片和根中分别发现了57和202个“记忆”基因，特别是发现了HHO3、AGL3、NHL、CML、DIR、CASP2、CASP3和ERF等多个“记忆”基因，它们参与蓖麻胁迫响应过程。说明这些“记忆”基因在蓖麻盐胁迫“记忆”的形成中发挥重要作用。基于基因组DNA甲基化分析，发现蓖麻经低盐锻炼后在盐胁迫下叶片DNA甲基化总体水平有下降的趋势，进一步分析发现低盐锻炼诱导蓖麻叶片CG、CHG和CHH甲基化在耐盐性状形成过程中都发生了明显的差异甲基化区域（differentially methylated regions, DMRs），且主要发生在基因区域。DMRs根据其甲基化变化规律主要分为2类，一类是低盐锻炼时甲基化发生变化，在恢复和高盐胁迫下继续维持甲基化变化的维持DMRs。一类是低盐锻炼后甲基化发生改变，在恢复阶段甲基化水平回复到对照水平的恢复DMRs。维持和恢复DMRs也是倾向于发生在基因区域。通过基因组DNA差异甲基化和转录组差异表达基因的关联分析，发现DNA甲基化在promoter和genebody区域主要抑制基因表达。我们鉴别了35个与DMRs紧密关联的差异表达基因，这些基因的功能广泛涉及蓖麻的盐胁迫反应过程。其中发现1个DMR甲基化的变化促进了“记忆”基因AGL3的表达，从而参与蓖麻盐胁迫“记忆”的形成。; Stress memory is a phenomenon that plants acquire stronger tolerance to subsequent stress after mild stress priming. Salt stress has become an important factor affecting the growth and development, yield, and quality of crops, which has seriously restricted the sustainable development of agriculture. Studies have shown that DNA methylation plays an important role in the formation and maintenance of plant stress memory. However, the role of DNA methylation variation in salt stress memory remains to be further clarified. Using castor salt sensitive varieties as the research object, RNA-seq and Whole Genome Bisulfite Sequencing (WGBS) were used to explore the molecular mechanism of DNA methylation regulating the formation of salt stress memory in castor bean. It was found that the salt tolerance of castor seedlings under high salt stress was significantly improved after low salt stress (priming). Physiologically, the acclimated seedlings accumulated less Na+ and H2O2 under high salt stress than those without priming. We found 57 and 202 memory genes in leaves and roots, especially HHO3, AGL3, NHL, CML, DIR, CASP2, CASP3 and ERF, which were involved in the response process of castor under salt stress. It is suggested that these memory genes play an important role in the formation of salt stress memory. Based on genomic DNA methylation analysis, it was found that the overall level of DNA methylation in castor leaves decreased after salt acclimation. Further analysis showed that CG, CHG and CHH methylation in castor leaves induced by low-salt priming had obvious differentially methylated regions (DMRs) during the formation of salt-tolerant traits, and mainly occurred in the gene region. DMRs can be divided into two types: one is that methylation changes during low-salt priming, and the methylation changes were maintained under recovery and high salt stress; one is the methylation changes after low-salt priming, and the methylation level returns to the control level after recovery. Through the association analysis of genomic DNA methylation and transcriptome, it was found that DNA methylation mainly inhibited gene expression in promoter and genebody regions. We identified 35 DEGs closely associated with DMRs. The functions of these genes are widely involved in the salt stress response of castor. It was found that the changes in a DMRs promoted the expression of memory gene AGL3, which was involved in the formation of salt stress memory in castor bean.
语种	中文
	2022-07
学位授予单位	中国科学院大学
文献类型	学位论文
条目标识符	http://ir.kib.ac.cn/handle/151853/75213
专题	昆明植物所硕博研究生毕业学位论文
推荐引用方式 GB/T 7714	李仕金. DNA甲基化参与蓖麻盐胁迫“记忆”形成的分子机理研究[D]. 中国科学院大学,2022.

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