目的:内部曝气对植物在淹水期间的生存很重要,形成aerenchyma的能力通过在芽和根之间创建连续的气体空间来贡献。玉米根(Zeamays)通过响应乙烯的程序性细胞死亡(PCD)在根皮质细胞中形成通erenchyma,从而对长期的淹水产生反应。这项研究的目的是通过鉴定玉米根皮质细胞中乙烯处理上调或下调的基因来了解乙烯诱导的细胞形成的分子机制。
方法:在有氧条件下用乙烯处理三天龄的玉米幼苗数小时。使用激光显微切割(LM)从原始根中分离出皮层细胞,通过微阵列比较了有和没有乙烯处理的转录物图谱。此外,对乙烯诱导的二苯基碘(DPI)细胞形成的影响,NADPH氧化酶的抑制剂,进行了检查,以评估活性氧(ROS)的参与。
结果:总共鉴定出223个基因,它们的转录水平在有氧条件下通过乙烯处理在根皮质细胞中显着增加或减少。随后的组织特异性定量逆转录PCR分析显示,乙烯增加了所有检查的根组织中与乙烯信号相关的基因的转录水平(石细胞,皮质细胞和外细胞层),而它增加了与皮质细胞中细胞壁修饰和蛋白水解相关的基因的转录水平。DPI处理抑制了乙烯诱导的细胞形成,并抑制了一些细胞壁修饰相关基因的表达。
结论:在乙烯处理的有氧条件下,在裂解性细胞形成过程中,一些与细胞壁修饰和蛋白水解相关的基因在皮质细胞中特异性上调或下调。结果表明,乙烯在恒星细胞中被感知,玉米初根的皮层细胞和外细胞层,皮质细胞特异性PCD通过随后的基因表达被控制在乙烯感知的下游,部分由ROS调节,在皮质细胞中。
OBJECTIVE: Internal aeration is important for plants to survive during periods of waterlogging, and the ability to form aerenchyma contributes by creating a continuous gas space between the shoots and the roots. Roots of maize (Zea mays) react to prolonged waterlogging by forming aerenchyma in root cortical cells by programmed cell death (PCD) in response to ethylene. The aim of this study was to understand the molecular mechanisms of ethylene-induced aerenchyma formation by identifying genes that are either up- or downregulated by ethylene treatment in maize root cortical cells.
METHODS: Three-day-old maize seedlings were treated with ethylene for several hours under aerobic conditions. Cortical cells were isolated from the primary roots using laser microdissection (LM), and transcript profiles with and without ethylene treatment were compared by microarray. In addition, the effect on ethylene-induced aerenchyma formation of diphenyleneiodonium (DPI), an inhibitor of NADPH oxidases, was examined in order to assess the involvement of reactive oxygen species (ROS).
RESULTS: A total of 223 genes were identified whose transcript levels were significantly increased or decreased by ethylene treatment in root cortical cells under aerobic conditions. Subsequent tissue-specific quantitative reverse-transcription PCR analyses revealed that ethylene increased the transcript levels of genes related to ethylene signalling in all of the root tissues examined (stelar cells, cortical cells and outer cell layers), whereas it increased the transcript levels of genes related to cell wall modification and proteolysis specifically in the cortical cells. DPI treatment inhibited the ethylene-induced aerenchyma formation and suppressed expression of some cell wall modification-related genes.
CONCLUSIONS: Several genes related to cell wall modification and proteolysis are specifically up- or downregulated in cortical cells during lysigenous aerenchyma formation under aerobic conditions with ethylene treatment. The results suggest that ethylene is perceived in stelar cells, cortical cells and outer cell layers in the maize primary root, and that the cortical cell-specific PCD is controlled downstream of ethylene perception through subsequent gene expression, which is partly regulated by ROS, in the cortical cells.