College of Horticulture, Beijing Key Laboratory of Growth and Developmental Regulation, China Agricultural University, Beijing, China.
School of Agriculture, Virginia State University, Petersburg, VA, USA.
Plant Cell Physiol. 2019 Mar 1;60(3):562-574. doi: 10.1093/pcp/pcy226.
Melatonin plays an important role in stress tolerance in plants. In this study, exogenous melatonin significantly alleviated the dwarf phenotype and inhibited the decrease of plant fresh weight induced by excess copper (Cu2+). Our results indicated that melatonin alleviated Cu2+ toxicity by improving Cu2+ sequestration, carbon metabolism and ROS (reactive oxygen species) scavenging, rather than by influencing the Cu2+ uptake under excess Cu2+ conditions. Transcriptome analysis showed that melatonin broadly altered gene expression under Cu2+ stress. Melatonin increased the levels of glutathione and phytochelatin to chelate excess Cu2+ and promoted cell wall trapping, thus keeping more Cu2+ in the cell wall and vacuole. Melatonin inhibited ROS production and enhanced antioxidant systems at the transcriptional level and enzyme activities, thus building a line of defense in response to excess Cu2+. The distribution of nutrient elements was recovered by melatonin which was disturbed by Cu2+. In addition, melatonin activated carbon metabolism, especially glycolysis and the pentose phosphate pathway, to generate more ATP, an intermediate for biosynthesis. Taken together, melatonin alleviated Cu2+ toxicity in cucumber via multiple mechanisms. These results will help to resolve the toxic effects of Cu2+ stress on plant growth and development. These results can be used for new strategies to solve problems associated with Cu2+ stress.
褪黑素在植物的应激耐受中起着重要作用。在这项研究中，外源褪黑素显著缓解了矮化表型，并抑制了过量铜（Cu2+）诱导的植物鲜重下降。我们的结果表明，褪黑素通过提高 Cu2+螯合、碳代谢和 ROS（活性氧）清除，而不是通过影响过量 Cu2+条件下的 Cu2+摄取，来缓解 Cu2+毒性。转录组分析表明，褪黑素在 Cu2+胁迫下广泛改变了基因表达。褪黑素增加了谷胱甘肽和植物螯合肽的水平，以螯合过量的 Cu2+，并促进细胞壁捕获，从而使更多的 Cu2+留在细胞壁和液泡中。褪黑素抑制 ROS 的产生，并在转录水平和酶活性上增强抗氧化系统，从而建立一条防线来应对过量的 Cu2+。褪黑素恢复了受 Cu2+干扰的营养元素的分布。此外，褪黑素激活了碳代谢，特别是糖酵解和戊糖磷酸途径，以产生更多的 ATP，这是生物合成的中间产物。综上所述，褪黑素通过多种机制缓解了黄瓜中的 Cu2+毒性。这些结果将有助于解决 Cu2+胁迫对植物生长和发育的毒害作用。这些结果可用于解决与 Cu2+胁迫相关问题的新策略。
