Department of Botany and Plant Sciences, Center for Plant Cell Biology, University of California, Riverside, California 92521, USA.
Plant Cell. 2011 Jan;23(1):412-27. doi: 10.1105/tpc.110.080325. Epub 2011 Jan 14.
Submergence and drought are major constraints to rice (Oryza sativa) production in rain-fed farmlands, both of which can occur sequentially during a single crop cycle. SUB1A, an ERF transcription factor found in limited rice accessions, dampens ethylene production and gibberellic acid responsiveness during submergence, economizing carbohydrate reserves and significantly prolonging endurance. Here, we evaluated the functional role of SUB1A in acclimation to dehydration. Comparative analysis of genotypes with and without SUB1A revealed that SUB1A enhanced recovery from drought at the vegetative stage through reduction of leaf water loss and lipid peroxidation and increased expression of genes associated with acclimation to dehydration. Overexpression of SUB1A augmented ABA responsiveness, thereby activating stress-inducible gene expression. Paradoxically, vegetative tissue undergoes dehydration upon desubmergence even though the soil contains sufficient water, indicating that leaf desiccation occurs in the natural progression of a flooding event. Desubmergence caused the upregulation of gene transcripts associated with acclimation to dehydration, with higher induction in SUB1A genotypes. SUB1A also restrained accumulation of reactive oxygen species (ROS) in aerial tissue during drought and desubmergence. Consistently, SUB1A increased the abundance of transcripts encoding ROS scavenging enzymes, resulting in enhanced tolerance to oxidative stress. Therefore, in addition to providing robust submergence tolerance, SUB1A improves survival of rapid dehydration following desubmergence and water deficit during drought.
淹水和干旱是雨养农田中水稻生产的主要限制因素，这两种因素在单个作物周期内都可能相继发生。在有限的水稻品种中发现的 ERF 转录因子 SUB1A 可以在淹水期间抑制乙烯的产生和赤霉素的反应性，从而节省碳水化合物储备，并显著延长其耐受力。在这里，我们评估了 SUB1A 在适应脱水过程中的功能作用。对具有和不具有 SUB1A 的基因型进行比较分析表明，SUB1A 通过减少叶片水分损失和脂质过氧化作用，以及增加与适应脱水相关的基因表达，从而增强了营养生长阶段对干旱的恢复能力。过量表达 SUB1A 增强了 ABA 的反应性，从而激活了胁迫诱导基因的表达。矛盾的是，尽管土壤中含有足够的水分，但淹水解除后营养组织也会发生脱水，这表明叶片的干燥是在洪水事件的自然发展过程中发生的。淹水解除后，与适应脱水相关的基因转录本上调，在 SUB1A 基因型中诱导更高。SUB1A 还抑制了干旱和淹水解除过程中空气组织中活性氧（ROS）的积累。一致地，SUB1A 增加了编码 ROS 清除酶的转录本的丰度，从而提高了对氧化应激的耐受性。因此，除了提供强大的耐淹水能力外，SUB1A 还提高了淹水解除后快速脱水和干旱期间水分亏缺的生存能力。
