Li Jianwu, Yang Jiao, Liang Xin, Zhan Shuping, Bai Yixuan, Ruan Li
College of Environment and Resources, Carbon Neutrality, Zhejiang A&F University, Hangzhou 311300, China.
Institute of Sericulture and Tea, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China.
Plants (Basel). 2025 May 9;14(10):1417. doi: 10.3390/plants14101417.
Lead (Pb) is a toxic heavy metal that severely impairs plant growth and crop quality. Melatonin, a widely present indoleamine compound, enhances plant stress tolerance, yet its role in tea plant resistance to lead stress remains unclear. This study examined two tea genotypes with distinct anthocyanin levels, Longjing43 (LJ43) and Zijuan (ZJ), comparing their phenotype, antioxidant capacity, secondary metabolite synthesis, and lead transport gene expression under lead stress. Excessive Pb exposure caused severe oxidative stress, reducing PSII efficiency, increasing ROS accumulation, and intensifying lipid peroxidation. ZJ, with higher anthocyanin concentration, exhibited stronger lead stress resistance than LJ43. Under lead stress, melatonin promoted phenylalanine accumulation in ZJ, facilitating its conversion into anthocyanins and catechins via key gene regulation (, , and ). Moreover, exogenous melatonin significantly reduced Pb concentrations in roots, stems, and leaves, with a more pronounced effect in ZJ (reductions of 20.46%, 53.30%, and 38.17%, respectively), which might be associated with the downregulation of Pb transport genes like (notably showing a 29-fold decrease). While these results suggest that melatonin might enhance Pb stress tolerance by modulating flavonoid metabolism and restricting Pb uptake, the specific roles of anthocyanins and catechins in this process remains to be fully elucidated. Further studies are necessary to clarify the primary bioactive compounds and mechanisms involved in melatonin-mediated heavy metal stress mitigation.
铅（Pb）是一种有毒重金属，会严重损害植物生长和作物品质。褪黑素是一种广泛存在的吲哚胺化合物，可增强植物的胁迫耐受性，但其在茶树抗铅胁迫中的作用仍不清楚。本研究考察了两种花青素水平不同的茶树基因型，龙井43（LJ43）和紫娟（ZJ），比较了它们在铅胁迫下的表型、抗氧化能力、次生代谢物合成以及铅转运基因表达。过量的铅暴露会导致严重的氧化应激，降低PSII效率，增加活性氧积累，并加剧脂质过氧化。花青素浓度较高的ZJ比LJ43表现出更强的铅胁迫抗性。在铅胁迫下，褪黑素促进了ZJ中苯丙氨酸的积累，通过关键基因调控（ 、 和 ）促进其转化为花青素和儿茶素。此外，外源褪黑素显著降低了根、茎和叶中的铅浓度，在ZJ中效果更明显（分别降低了20.46%、53.30%和38.17%），这可能与 等铅转运基因的下调有关（显著下降了29倍）。虽然这些结果表明褪黑素可能通过调节类黄酮代谢和限制铅吸收来增强对铅胁迫的耐受性，但花青素和儿茶素在这一过程中的具体作用仍有待充分阐明。有必要进一步研究以明确参与褪黑素介导的重金属胁迫缓解的主要生物活性化合物和机制。
