Endogenous melatonin deficiency aggravates high temperature-induced oxidative stress in Solanum lycopersicum L.
Endogenous melatonin deficiency aggravates high temperature-induced oxidative stress in Solanum lycopersicum L.
复制标题
内源性褪黑激素缺乏加剧了番茄高温诱导的氧化应激。
DOI：
10.1016/j.envexpbot.2018.06.006
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发表时间：
2019-05-01
影响因子：
5.7
通讯作者：
Chen, Shuangchen
中科院分区：
文献类型：
--
作者：
Ahammed, Golam Jalal;Xu, Wen;Chen, Shuangchen
褪黑素是一种天然的生物刺激分子，存在于许多植物物种中。尽管植物褪黑激素的研究历史很短，但褪黑素在植物胁迫反应中的关键作用已经被广泛地记录在案。然而，大多数这类研究构成了药理学方法，而探索内源性褪黑素相关性的研究很少。为了揭示内源褪黑素在植物耐热性中的作用，我们通过沉默参与褪黑素生物合成的基因咖啡酸O-甲基转移酶1(COMT1)，获得了褪黑素缺乏的番茄植株。我们首先研究了外源褪黑素的影响，然后详细分析了褪黑素缺乏对番茄植株氧化胁迫标记物、酶和非酶抗氧化剂以及氧化还原动态平衡的影响。结果表明，抑制内源褪黑素对番茄耐高温胁迫的影响与抑制外源褪黑素相反。内源褪黑素缺乏加剧了高温诱导的氧化胁迫，表现为番茄叶片的电解质渗漏率、丙二醛浓度增加，氧化和不溶蛋白积累增加。这些变化伴随着抗坏血酸过氧化物酶和过氧化氢酶活性的显著降低，这两个关键抗氧化酶在植物耐热性中起着突出的作用。此外，COMT1的沉默改变了氧化还原平衡，这反映在高温胁迫下GSH/GSSG和ASA：DHA的比率显著降低。相反，外源褪黑素提高了COMT1沉默植物的内源褪黑素水平，并缓解了热诱导的氧化胁迫。我们的结果表明，合适的内源性褪黑素水平不仅对其自身抗氧化能力至关重要，而且对于在扰动的环境条件下维持有效的酶促抗氧化系统和氧化还原动态平衡也是至关重要的。
Melatonin is a natural biostimulating molecule that occurs in a number of plant species. Despite a short history of phytomelatonin research, the critical roles of melatonin in plant stress responses have extensively been documented. However, the majority of such studies constitute 'pharmacological approach' and studies exploring the relevance of endogenous melatonin are scanty. As an attempt to unmask the role of endogenous melatonin in plant thermotolerance, we generated melatonin deficient tomato plants by silencing a gene, CAFFEIC ACID O-METHYLTRANSFERASE 1 (COMT1), involved in melatonin biosynthesis. We first examined the effect of exogenous melatonin and then performed a detailed analysis of the effect of melatonin deficiency on oxidative stress markers, enzymatic and non-enzymatic antioxidants, and redox homeostasis in tomato plants. The results showed that suppression of endogenous melatonin had an opposite effect of exogenous melatonin on tomato tolerance to high temperature stress. Endogenous melatonin deficiency aggravated high temperature-induced oxidative stress as evidenced by increased electrolyte leakage percentage, malondialdehyde concentration, and oxidized and insoluble protein accumulation in tomato leaves. These changes were accompanied with the significant reductions in the activity of ascorbate peroxidase and catalase, two key antioxidant enzymes that play prominent role in plant thermotolerance. Furthermore, silencing of COMT1 altered redox balance as reflected by the significantly decreased ratios of GSH:GSSG and AsA:DHA under high temperature stress. In contrast, exogenous melatonin augmented the endogenous melatonin level in COMT1-silenced plants and alleviated the heat-induced oxidative stress. Our results suggest that an optimal endogenous melatonin level is critical, not only for its self-antioxidant capacity, but also for maintaining an efficient enzymatic antioxidant system and redox homeostasis under perturbed environmental conditions.