Institute of Plant Stress Biology, State Key Laboratory of Cotton Biology, Department of Biology, Henan University, 85 Minglun Street, Kaifeng 475001, China.
Stress Adaptation Research Unit, RIKEN Center for Sustainable Resource Science, 1-7-22, Suehiro-cho, Tsurumi, Yokohama 230-0045, Japan.
Biomolecules. 2020 Apr 14;10(4):607. doi: 10.3390/biom10040607.
Previous investigations have shown that the SUPPRESSORS OF MAX2 1-LIKE6, 7 and 8 (SMXL6, 7 and 8) proteins redundantly repress strigolactone (SL) signaling in plant growth and development. Recently, a growing body of evidence indicated that SLs positively regulate plant drought resistance through functional analyses of genes involved in SL biosynthesis and positive regulation of SL signaling. However, the functions of the SL-signaling negative regulators SMXL6, 7 and 8 in drought resistance and the associated mechanisms remain elusive. To reveal the functions of these SMXL proteins, we analyzed the drought-resistant phenotype of the triple ,, mutant plants and studied several drought resistance-related traits. Our results showed that the ,, mutant plants were more resistant to drought than wild-type plants. Physiological investigations indicated that the ,, mutant plants exhibited higher leaf surface temperature, reduced cuticle permeability, as well as decreases in drought-induced water loss and cell membrane damage in comparison with wild-type plants. Additionally, ,, mutant plants displayed an increase in anthocyanin biosynthesis during drought, enhanced detoxification capacity and increased sensitivity to abscisic acid in cotyledon opening and growth inhibition assays. A good correlation between the expression levels of some relevant genes and the examined physiological and biochemical traits was observed. Our findings together indicate that the SMXL6, 7 and 8 act as negative regulators of drought resistance, and that disruption of these genes in crops may provide a novel way to improve their drought resistance.
先前的研究表明，MAX2 抑制子 1 样蛋白 6、7 和 8（SMXL6、7 和 8）在植物生长发育中冗余地抑制独脚金内酯（SL）信号。最近，越来越多的证据表明，SL 通过参与 SL 生物合成的基因的功能分析以及 SL 信号的正向调控，正向调节植物抗旱性。然而，SL 信号负调节因子 SMXL6、7 和 8 在抗旱性中的功能及其相关机制仍不清楚。为了揭示这些 SMXL 蛋白的功能，我们分析了三重 ，，突变体植物的抗旱表型，并研究了几个与抗旱性相关的性状。我们的结果表明，与野生型植物相比，，，突变体植物对干旱更具抗性。生理研究表明，与野生型植物相比，，，突变体植物的叶片表面温度更高，角质层渗透率降低，干旱诱导的水分损失和细胞膜损伤减少。此外，在干旱胁迫下，，，突变体植物的花青素生物合成增加，在子叶张开和生长抑制试验中，解毒能力增强，对脱落酸的敏感性增加。观察到一些相关基因的表达水平与所检查的生理生化性状之间存在良好的相关性。我们的研究结果表明，SMXL6、7 和 8 作为抗旱性的负调节因子，破坏这些基因可能为提高作物的抗旱性提供一种新方法。
