Signaling Pathway Research Unit, RIKEN Center for Sustainable Resource Science, Yokohama 230-0045, Japan.
Proc Natl Acad Sci U S A. 2014 Jan 14;111(2):851-6. doi: 10.1073/pnas.1322135111. Epub 2013 Dec 30.
This report provides direct evidence that strigolactone (SL) positively regulates drought and high salinity responses in Arabidopsis. Both SL-deficient and SL-response [more axillary growth (max)] mutants exhibited hypersensitivity to drought and salt stress, which was associated with shoot- rather than root-related traits. Exogenous SL treatment rescued the drought-sensitive phenotype of the SL-deficient mutants but not of the SL-response mutant, and enhanced drought tolerance of WT plants, confirming the role of SL as a positive regulator in stress response. In agreement with the drought-sensitive phenotype, max mutants exhibited increased leaf stomatal density relative to WT and slower abscisic acid (ABA)-induced stomatal closure. Compared with WT, the max mutants exhibited increased leaf water loss rate during dehydration and decreased ABA responsiveness during germination and postgermination. Collectively, these results indicate that cross-talk between SL and ABA plays an important role in integrating stress signals to regulate stomatal development and function. Additionally, a comparative microarray analysis of the leaves of the SL-response max2 mutant and WT plants under normal and dehydrative conditions revealed an SL-mediated network controlling plant responses to stress via many stress- and/or ABA-responsive and cytokinin metabolism-related genes. Our results demonstrate that plants integrate multiple hormone-response pathways for adaptation to environmental stress. Based on our results, genetic modulation of SL content/response could be applied as a potential approach to reduce the negative impact of abiotic stress on crop productivity.
本报告提供了直接证据表明，独脚金内酯（SL）正向调控拟南芥的干旱和高盐响应。SL 缺陷和 SL 响应[更多侧枝生长（max）]突变体均对干旱和盐胁迫表现出超敏反应，这与地上部而非根部相关性状有关。外施 SL 处理挽救了 SL 缺陷突变体的干旱敏感表型，但不能挽救 SL 响应突变体，并且增强了 WT 植物的耐旱性，证实了 SL 作为正向调节剂在应激反应中的作用。与干旱敏感表型一致，max 突变体相对于 WT 表现出增加的叶片气孔密度和较慢的脱落酸（ABA）诱导的气孔关闭。与 WT 相比，max 突变体在脱水过程中表现出增加的叶片水分损失率，并且在萌发和萌发后表现出降低的 ABA 反应性。总的来说，这些结果表明，SL 和 ABA 之间的串扰在整合应激信号以调节气孔发育和功能方面起着重要作用。此外，在正常和脱水条件下，SL 响应 max2 突变体和 WT 植物叶片的比较微阵列分析揭示了一个由 SL 介导的网络，通过许多应激和/或 ABA 响应和细胞分裂素代谢相关基因来控制植物对胁迫的反应。我们的结果表明，植物整合了多个激素反应途径以适应环境胁迫。基于我们的结果，SL 含量/响应的遗传调节可作为一种潜在的方法来减少非生物胁迫对作物生产力的负面影响。
