【摘要】 表观遗传变异影响表型多样性越来越受到关注,然而其内部调控机制,仍没有较为明确而系统的阐述。为了阐述其叶长表型多样性的表观遗传学机制,本实验研究了27个生态型拟南芥(Arabidopsis thaliana)种群的叶长多样性与相关基因甲基化变异的关系,试图揭示其表观遗传调控机制。研究结果发现,不同生态型拟南芥叶长呈现出丰富的遗传多样性,通过甲基化抑制剂5-氮杂胞苷(5-azacytidine,5-aza C)去甲基化处理后,各种群叶长多样性变异降低,表现为叶长较长的拟南芥种群叶长缩短,而叶长较短的拟南芥种群叶长呈增长的变化趋势。生物信息学分析揭示拟南芥叶长发育通路中4个swp(struwwelpeter,SWP)、生长素响应因子2(auxin response factor 2,ARF2)、生长调节因子1(growthregulating factor 1,GRF1)、Erb B-3表皮生长因子受体结合蛋白(erbb-3 epidermal growth factor receptor binding protein,EBP1)基因的甲基化程度与拟南芥叶长显著正相关。继而比较了这些基因在其中的3个典型拟南芥种群的野生型及其5-aza C处理后的表达模式,结果表明,在野生型拟南芥种群中,这些基因的表达量与基因甲基化程度及叶长呈显著正相关;而5-aza C处理后不同拟南芥种群间基因表达量差异降低。即去甲基化处理导致了3个典型拟南芥种群间SWP、ARF2、GRF1和EBP1基因表达量差异减小,这与去甲基化处理后拟南芥叶长表型多样性降低相关,说明SWP、ARF2、GRF1和EBP1基因的甲基化参与了拟南芥叶长多样性的调控。综上所述,本研究揭示了拟南芥叶长的多样性是受叶长发育关键基因的甲基化变异调控所致,从而进一步的揭示了甲基化表观遗传修饰对于拟南芥叶长表型可塑性的内部调控机制。更多还原

【Abstract】 Influence of epigenetic variation on phenotypic diversity has become a research hotspot recently.However,it remains largely unknown how epigenetic variation regulates plant phenotypic diversity.In this research,the leaf length diversity of 27 Arabidopsis thaliana genotypes and its correlation with DNA methylation of related genes to leaf development were studied.The results showed that a great leaf length diversity existed among different A.thaliana genotypes.After treatment with demethylation agent 5-azacytidine(5-aza C),leaf length variation of different genotypes decreased significantly.The leaf length of long-leaved A.thaliana genotypes decreased after 5-aza C treatment while short-leaved populations tend to increase.Leaf development related genes of different A.thaliana genotypes showed various DNA methylation levels via bioinformatics analysis.Meanwhile,leaf length of different A.thaliana genotypes were positively and significantly correlated with DNA methylation of 4 genes struwwelpeter(SWP),auxin response factor 2(ARF2),growth-regulating factor 1(GRF1),erbb-3 epidermal growth factor receptor binding proteinebp1(EBP1)which involved in A.thaliana leaf development.Three typical A.thaliana genotypes with different leaf lengths,long-leaved Gr-1,mediate leaved Ty-0 and short-leaved Br-0,were selected and used for gene expression analysis.The results showed that long-leaved Gr-1 had highest methylation levels of SWP,ARF2,GRF1 and EBP1 genes among the three selected populations while short-leaved Br-0 had lowest methylation levels of SWP,ARF2 and GRF1 and mediate methylated EBP1 gene.Q-PCR analysis showed that expression levels of these 4 genes were positively correlated with DNA methylation level and leaf length of A.thaliana genotypes,respectively.Gr-1 had the highest expression levels of SWP,ARF2,GRF1 and EBP1 genes compared with the other two populations.Br-0 had the lowest expression of SWP,ARF2 and GRF1 genes and the mediate expression level of EBP1 gene.However,relative expression level differences of these 4 genes among the 3 genotypes decreased significantly after 5-aza C treatment.The relative expression levels of SWP,ARF2,GRF1 and EBP1 in Gr-1 decreased significantly after 5-aza C treatment while relative expression levels of those four genes in Br-0 increased.In conclusion,demethylation of these 4 genes led to smaller relative expression level differences among the 3 populations,which contributed to the less leaf length diversity.These results indicated that DNA methylation of SWP,ARF2,GRF1 and EBP1 genes play a role in regulating leaf length diversity of A.thaliana.This may provide a basis for further study of the role of epigenetic variation on plants phenotypic diversity.更多还原