Virginia Bioinformatics Institute , Virginia Tech, Blacksburg, Virginia 24061, USA.
Plant Physiol. 2012 Oct;160(2):846-67. doi: 10.1104/pp.112.200444. Epub 2012 Jul 26.
Drought stress affects cereals especially during the reproductive stage. The maize (Zea mays) drought transcriptome was studied using RNA-Seq analysis to compare drought-treated and well-watered fertilized ovary and basal leaf meristem tissue. More drought-responsive genes responded in the ovary compared with the leaf meristem. Gene Ontology enrichment analysis revealed a massive decrease in transcript abundance of cell division and cell cycle genes in the drought-stressed ovary only. Among Gene Ontology categories related to carbohydrate metabolism, changes in starch and Suc metabolism-related genes occurred in the ovary, consistent with a decrease in starch levels, and in Suc transporter function, with no comparable changes occurring in the leaf meristem. Abscisic acid (ABA)-related processes responded positively, but only in the ovaries. Related responses suggested the operation of low glucose sensing in drought-stressed ovaries. The data are discussed in the context of the susceptibility of maize kernel to drought stress leading to embryo abortion and the relative robustness of dividing vegetative tissue taken at the same time from the same plant subjected to the same conditions. Our working hypothesis involves signaling events associated with increased ABA levels, decreased glucose levels, disruption of ABA/sugar signaling, activation of programmed cell death/senescence through repression of a phospholipase C-mediated signaling pathway, and arrest of the cell cycle in the stressed ovary at 1 d after pollination. Increased invertase levels in the stressed leaf meristem, on the other hand, resulted in that tissue maintaining hexose levels at an "unstressed" level, and at lower ABA levels, which was correlated with successful resistance to drought stress.
干旱胁迫尤其会影响到作物的生殖阶段。本研究采用 RNA-Seq 分析技术，对玉米（Zea mays）干旱转录组进行了研究，以比较干旱处理和充分浇水施肥的授粉后子房和基部叶片分生组织。与叶片分生组织相比，更多的干旱响应基因在子房中有响应。GO 富集分析表明，只有在干旱胁迫的子房中，细胞分裂和细胞周期基因的转录丰度才会大量减少。在与碳水化合物代谢相关的 GO 类别中，淀粉和蔗糖代谢相关基因在子房中的变化与淀粉水平降低一致，蔗糖转运蛋白功能降低，而在叶片分生组织中没有发生类似的变化。ABA 相关过程呈正响应，但仅在子房中有响应。相关响应表明，在干旱胁迫的子房中存在葡萄糖低感应作用。我们将数据放在背景中进行讨论，即玉米籽粒对干旱胁迫的敏感性导致胚胎流产，而在同一植株上同时从同一植物中取出的分裂营养组织具有相对的健壮性，其处于相同的条件下。我们的工作假说涉及与 ABA 水平升高、葡萄糖水平降低、ABA/糖信号中断、通过抑制 PLC 介导的信号通路激活程序性细胞死亡/衰老、以及授粉后 1 天胁迫子房中细胞周期停滞相关的信号事件。另一方面，胁迫叶片分生组织中转化酶水平的升高导致该组织保持六碳糖水平处于“未胁迫”水平，并降低 ABA 水平，这与成功抵抗干旱胁迫有关。
