Transcriptome analysis of four maize lines to detect the different responses to chilling stress and reveal the survival mechanisms in maize. Transcriptome analysis of four maize lines to detect the different responses to chilling stress and reveal the survival mechanisms in maize

Purpose: The goal of this analysis is that to reveal the different expression pattern in chilling-tolerant and chilling susceptible lines under chilling stress.Chilling is a major stress to plants of subtropical and tropical origins including maize. To reveal molecular mechanisms underlying chilling tolerance and chilling survival, we investigated maize transcriptome responses to chilling stress in differentiated leaves and roots as well as in crowns with meristem activity for survival. Chilling stress on maize shoots and roots is found to each contribute to seedling lethality in maize. Comparison of maize lines with different chilling tolerance capacity reveals that chilling survival in maize is highly associated with upregulation in leaves and crowns of abscisic acid response pathway, transcriptional regulators and metal ion transporters as well as downregulation of heat response in crowns. Comparison of chilling treatment on whole and part of the plants reveals that response to distal-chilling is very distinct from, and sometimes opposite to, response to local- or whole-plant chilling in both leaves and roots, suggesting a communication between shoots and roots in environmental perception. In sum, this study details chilling responses in leaves, roots and crowns and reveals potential chilling survival mechanism in maize, which lays ground for further understanding survival and tolerance mechanisms under low but non-freezing temperatures in tropical and subtropical plants. Overall design: Examination of 4 different maize lines, and normal temperature for control group, while 4 treatment for experiment group.研究目的：本研究旨在揭示耐冷系（chilling-tolerant lines）与冷敏感系（chilling susceptible lines）在冷胁迫（chilling stress）下的基因表达差异模式。冷胁迫是包括玉米在内的亚热带、热带起源植物面临的主要逆境之一。为解析耐冷性与冷存活背后的分子机制，本研究针对玉米已分化叶片、根部，以及具有分生组织（meristem）活性、参与冷存活过程的冠部，分析了其在冷胁迫下的转录组（transcriptome）响应。研究发现，玉米地上部与根部所受的冷胁迫均会导致幼苗死亡。对不同耐冷能力玉米品系的比较分析显示，玉米的冷存活能力与叶片及冠部中脱落酸（abscisic acid）响应通路、转录调控因子及金属离子转运蛋白的上调表达高度相关，同时与冠部中热响应通路的下调表达密切关联。对整株及局部植株施加冷胁迫的对比实验表明，远距冷胁迫响应与局部或整株冷胁迫响应在叶片与根部中差异显著，甚至有时完全相反，这暗示玉米地上部与根部在环境感知过程中存在信号交流。综上，本研究详细阐明了玉米叶片、根部及冠部的冷胁迫响应机制，揭示了玉米潜在的冷存活通路，为进一步理解热带、亚热带植物在低非冻结低温下的存活与耐冷机制奠定了基础。 实验设计：本实验共纳入4个不同玉米品系，以常温处理作为对照组，以4组冷胁迫处理作为实验组。