Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, Sichuan, PR China.
Plant Cell Physiol. 2018 Nov 1;59(11):2381-2393. doi: 10.1093/pcp/pcy164.
Light signaling and phytohormones play important roles in plant growth, development, and biotic and abiotic stress responses. However, the roles of phytochromes and cross-talk between these two signaling pathways in response to salt stress in tobacco plants remain underexplored. Here, we explored the defense response in phytochrome-defective mutants under salt stress. We monitored the physiological and molecular changes of these mutants under salt stress conditions. The results showed that phytochrome A (phyA), phytochrome B (phyB) and phyAphyB (phyAB) mutants exhibited improved salt stress tolerance compared with wild-type (WT) plants. The mutant plants had a lower electrolyte leakage (EL) and malondialdehyde (MDA) concentration than WT plants, and the effect was clearly synergistic in the phyAB double mutant plants. Furthermore, the data showed that the transcript levels of defense-associated genes and the activities of some antioxidant enzymes in the mutant plants were much higher than those in WT plants. Additionally, the results indicated that phytochrome signaling strongly modulates the expression of endogenous abscisic acid (ABA) and jasmonic acid (JA) of Nicotiana tobacum in response to salt stress. To illustrate further the relationship between phytochrome and phytohormone, we measured the expression of defense genes and phytochrome. The results displayed that salt stress and application of methyl jasmonate (MeJA) or ABA up-regulated the transcript levels of salt response-associated genes and inhibited the expression of NtphyA and NtphyB. Foliar application of inhibitors of ABA and JA further confirmed that JA co-operated with ABA in phytochrome-mediated salt stress tolerance.
光信号和植物激素在植物生长、发育以及生物和非生物胁迫响应中起着重要作用。然而，在烟草植物中，光敏色素和这两种信号通路之间的相互作用在盐胁迫响应中的作用仍未得到充分探索。在这里，我们研究了盐胁迫下光敏色素缺陷突变体的防御反应。我们监测了这些突变体在盐胁迫条件下的生理和分子变化。结果表明，与野生型（WT）植物相比，光敏色素 A（phyA）、光敏色素 B（phyB）和 phyAphyB（phyAB）突变体表现出更好的耐盐胁迫能力。突变体植物的电解质渗漏（EL）和丙二醛（MDA）浓度比 WT 植物低，phyAB 双突变体植物的效果明显协同。此外，数据表明，突变体植物中防御相关基因的转录水平和一些抗氧化酶的活性远高于 WT 植物。此外，结果表明，光敏色素信号强烈调节拟南芥内源脱落酸（ABA）和茉莉酸（JA）的表达，以响应盐胁迫。为了进一步说明光敏色素和植物激素之间的关系，我们测量了防御基因和光敏色素的表达。结果表明，盐胁迫和施用茉莉酸甲酯（MeJA）或 ABA 上调了与盐反应相关基因的转录水平，并抑制了 NtphyA 和 NtphyB 的表达。ABA 和 JA 抑制剂的叶面喷施进一步证实了 JA 与 ABA 在光敏色素介导的耐盐胁迫中协同作用。
