Chang Jingjing, Zhu Xuemei, Lian Yixuan, Li Jing, Chen Xiao, Song Zhao, Chen Lei, Xie Dasen, Zhang Baige
Key Laboratory for New Technology Research of Vegetable, Vegetable Research Institute, Guangdong Academy of Agricultural Science, Guangzhou 510640, China.
Antioxidants (Basel). 2024 Dec 22;13(12):1580. doi: 10.3390/antiox13121580.
In plants, calcium (Ca) serves as an essential nutrient and signaling molecule. Melatonin is a biologically active and multi-functional hormone that plays an important role in improving nutrient use efficiency. However, its involvement in plant responses to Ca deficiency remains largely unexplored. This study aimed to assess the effects of melatonin on Ca absorption, the antioxidant system, and root morphology under low-Ca (LCa) stress conditions, as well as to identify key regulatory factors and signaling pathways involved in these processes using transcriptome analysis. Under LCa conditions, wax gourd seedling exhibited significant decreases in Ca accumulation, showed inhibition of root growth, and demonstrated the occurrence of oxidative damage. However, melatonin application significantly enhanced Ca content in wax gourd seedlings, and it enhanced the absorption of Ca in roots by upregulating Ca channels and transport genes, including , , , , and . Furthermore, the application of exogenous melatonin mitigated the root growth inhibition and oxidative damage caused by LCa stress. This was evidenced by increases in the root branch numbers, root tips, root surface area, and root volume, as well as enhanced root vitality and antioxidant enzyme activities, as well as decreases in the reactive oxygen species content in melatonin treated plants. Transcriptome results revealed that melatonin mainly modulated the brassinosteroids (BRs) and auxin signaling pathway, which play essential roles in root differentiation, elongation, and stress adaptation. Specifically, melatonin increased the active BR levels by upregulating (a BR biosynthesis gene) and downregulating (BR degradation genes), thereby affecting the BR signaling pathway. Additionally, melatonin reduced IAA levels but activated the auxin signaling pathway, indicating that melatonin could directly stimulate the auxin signaling pathway via an IAA-independent mechanism. This study provides new insights into the role of melatonin in nutrient stress adaptation, offering a promising and sustainable approach to improve nutrient use efficiency in wax gourd and other crops.
在植物中，钙（Ca）是一种必需的营养物质和信号分子。褪黑素是一种具有生物活性的多功能激素，在提高养分利用效率方面发挥着重要作用。然而，其在植物对缺钙反应中的作用在很大程度上仍未得到探索。本研究旨在评估褪黑素在低钙（LCa）胁迫条件下对钙吸收、抗氧化系统和根系形态的影响，并通过转录组分析确定参与这些过程的关键调控因子和信号通路。在LCa条件下，冬瓜幼苗的钙积累显著减少，根系生长受到抑制，并出现氧化损伤。然而，施用褪黑素显著提高了冬瓜幼苗的钙含量，并通过上调钙通道和转运基因，包括、、、和，增强了根系对钙的吸收。此外，外源褪黑素的施用减轻了LCa胁迫引起的根系生长抑制和氧化损伤。这表现为褪黑素处理植株的根分支数、根尖数、根表面积和根体积增加，根系活力和抗氧化酶活性增强，活性氧含量降低。转录组结果显示，褪黑素主要调节油菜素内酯（BRs）和生长素信号通路，这两条信号通路在根系分化、伸长和胁迫适应中起着至关重要的作用。具体而言，褪黑素通过上调（一个BR生物合成基因）和下调（BR降解基因）来提高活性BR水平，从而影响BR信号通路。此外，褪黑素降低了IAA水平，但激活了生长素信号通路，表明褪黑素可以通过一种不依赖IAA的机制直接刺激生长素信号通路。本研究为褪黑素在养分胁迫适应中的作用提供了新的见解，为提高冬瓜和其他作物的养分利用效率提供了一种有前景的可持续方法。
