College of Horticulture, Northwest Agricultural & Forest University, Yangling, Shaanxi, China.
College of Horticulture, Shanxi Agricultural & Forest University, Taigu, Shanxi, China.
Sci Rep. 2017 Jul 10;7(1):4998. doi: 10.1038/s41598-017-05267-3.
To obtain new insights into the mechanisms of the positive effects of exogenous melatonin applications to cucumber seedlings during chilling, we investigated its role in regulating photosynthesis, the transcription level of csZat12 and the metabolism of polyamines (PAs) and of abscisic acid (ABA). The negative effects of chilling were clearly alleviated in cucumber seedlings by irrigation with 200 μM melatonin solution. This was evidenced by alleviation of the decline in net photosynthesis rate and also in electrolyte leakage in chilled plants. The reasons for this can be explained as follows. First, melatonin up-regulates CsZat12, an important stress-related gene. Second, melatonin increases the content of putrescine (Put) and spermidine (Spd) and stabilized spermine (Spm) by altering the activity of the PA metabolic enzymes. And, third, ABA is also involved in these effects as melatonin modulated the expression of the key ABA biosynthesis genes (CsNCED1 and CsNCED2) and also the key ABA catabolism genes (CsCYP707A1 and CsCYP707A2). This study provides new evidence suggesting melatonin mitigates chilling stress in cucumber by up-regulating the expression of CsZat12 and by modulating the metabolism of PAs and ABA.
为了深入了解外源褪黑素应用于黄瓜幼苗缓解冷藏胁迫的积极作用的机制，我们研究了褪黑素在调节光合作用、csZat12 转录水平以及多胺（PAs）和脱落酸（ABA）代谢中的作用。用 200μM 褪黑素溶液灌溉明显减轻了冷藏对黄瓜幼苗的负面影响。这可以通过缓解净光合速率的下降和冷胁迫植物的电解质渗漏来证明。其原因如下。首先，褪黑素上调了 CsZat12，这是一个重要的应激相关基因。其次，褪黑素通过改变 PA 代谢酶的活性，增加腐胺（Put）和亚精胺（Spd）的含量，并稳定精胺（Spm）。第三，ABA 也参与了这些作用，因为褪黑素调节了关键 ABA 生物合成基因（CsNCED1 和 CsNCED2）和关键 ABA 分解代谢基因（CsCYP707A1 和 CsCYP707A2）的表达。本研究提供了新的证据，表明褪黑素通过上调 CsZat12 的表达以及调节 PAs 和 ABA 的代谢来缓解黄瓜的冷藏胁迫。
