DNA甲基化参与调控马铃薯干旱胁迫响应

非生物胁迫下表观遗传对调控植物基因表达起重要作用,但是有关马铃薯干旱胁迫下的表观遗传研究甚少。本研究以马铃薯品种大西洋、费乌瑞它、C119、C16和青薯9号为试验材料,以MS培养基为对照以及分别添加200 mmol L~(-1)甘露醇、60μmol L~(-1)甲基化抑制剂(5-azadC)和60μmol L~(-1)甲基化抑制剂+200 mmol L~(-1)甘露醇,处理24 d后对试管苗表型性状和生理指标进行综合分析。结果发现,不同品种马铃薯对甘露醇和甲基化抑制剂响应程度趋势类似。在干旱和DNA甲基化抑制剂分别处理下,马铃薯植株干鲜重、株高、叶片数和叶绿素含量均显著减少(P0.05), SOD、POD、CAT活性和Pro、MDA含量均显著增加(P0.05),而分枝数、根长、平均根粗均无明显变化,表明马铃薯不同性状指标在响应干旱胁迫和DNA去甲基化时,受到的调控通路可能不同。进一步比较干旱胁迫和DNA去甲基化共同处理与分别处理下表型性状和生理指标的差异发现,共同处理使马铃薯植株表型性状受到进一步抑制,同时活化了SOD、POD、CAT,并且使Pro、MDA含量增加,表明马铃薯在响应干旱胁迫过程中,部分表型的形成与DNA甲基化调控相关。这将为深入研究马铃薯干旱胁迫响应与表观遗传学之间的调控网络通路提供初步的理论基础。

DNA methylation involved in regulating drought stress response of potato

Although epigenetics is essential for regulating gene expression in plant under abiotic stress, there are few reports regarding the epigenetics of potato under drought stress. In this study, five potato cultivars including Atlantic, Favorita, C119, C16, and Qingshu 9, were used to verify that DNA methylation is involved in potato drought stress response. The plantlets were cultured for 24 days on MS medium, MS medium supplemented with 60 μmol L ^-1 methylation inhibitor (5-azadC), 200 mmol L ^-1 mannitol, and 60 μmol L ^-1 methylation inhibitor combined with 200 mmol L ^-1 mannitol, respectively. Phenotypes, and physiological and biochemical traits were recorded and comprehensively analyzed. The response of five potato cultivars to mannitol and 5-azadC was similar. With treatments of mannitol or 5-azadC, the dry/fresh weight, shoot height, leaf number and chlorophyll content decreased significantly (P < 0.05), while the activities of SOD, POD, CAT, and contents of proline and MDA increased significantly (P < 0.05). No significant changes were observed in branch number, root length and average root diameter, indicating that potato traits might have different regulatory pathways in response to drought stress and DNA demethylation. Compared with the individual treatment, combined-treatment further inhibited the growth of plantlets, and increased activities of SOD, POD, CAT, and contents of MDA and Pro under drought stress and 5-azadC treatment, indicating that the formation of some phenotypes (not all) in response to drought was regulated through the DNA methylation. The results provide preliminary data for further study on epigenetics regulatory pathway of potato under drought stress.