International Research Center for Environmental Membrane Biology, Foshan University, Foshan, China.
International Research Center for Environmental Membrane Biology, Foshan University, Foshan, China.
Ecotoxicol Environ Saf. 2024 Sep 15;283:116768. doi: 10.1016/j.ecoenv.2024.116768. Epub 2024 Jul 26.
Increased anthropogenic activities over the last decades have led to a gradual increase in cadmium content in the soil, which, due to its high mobility in soil, makes Cd accumulation in plants a serious threat to the health of animals and humans. Plant hormones including melatonin (Mel) and brassinosteroids (BR) are known to provide tolerance against various abiotic stresses. In this work, the role of combined and separate exogenous application of Mel and BR on Cd stress in cherry tomato plants was examined. Cd stress significantly reduced tomato growth by inducing oxidative stress and reduced K uptake in roots and shoots. Combined application of Mel and BR reduced detrimental effects of Cd in tomato by (i) reducing Cd accumulation in the shoot; (ii) increasing the activities of different antioxidants (SOD, CAT, APX, GR); (iii) triggering higher expression of genes relating to Cd vacuolar sequestration (Na/H EXCHANGER, SlNHX1; NATURAL RESISTANCE-ASSOCIATED MACROPHAGE PROTEIN 6, SlNRAMP6), and Cd transport and detoxification (HEAVY-METAL-ASSOCIATED 3, SlHMA3; PLANT CADMIUM RESISTANT 2, SlPCR2); and (iv) improving plant K homeostasis and contents in root and shoot. The latter trait was associated with the reduced gene expression of K-permeable outward rectifying channel (SlGORK3), and transcriptional upregulation of high affinity potassium transporter 5 (SIHAK5) under Cd stress. A separate application of Mel and BR showed tissue-specific regulation of tomato growth and Cd tolerance by regulating antioxidant activities, K uptake, Cd uptake, and translocation from root to shoot and their endogenous contents. Melatonin per se was more effective in improving Cd tolerance in shoot while beneficial BR effects were more pronounced in roots, and their combined application was effective in both tissues. Taken together, reported results show tissue-specific regulation of Cd tolerance by Mel and BR in cherry tomato plants and demonstrate the efficiency of combined Mel + BR treatment as a practical tool to reduce Cd accumulation and mitigate its negative effects on plant growth.
在过去几十年中，人为活动的增加导致土壤中镉含量逐渐增加，由于镉在土壤中具有很高的迁移性，因此镉在植物中的积累对动物和人类的健康构成了严重威胁。已知植物激素包括褪黑素（Mel）和油菜素内酯（BR）可以提供对各种非生物胁迫的耐受性。在这项工作中，研究了外源施用 Mel 和 BR 对樱桃番茄植株镉胁迫的单独和联合作用。镉胁迫通过诱导氧化应激和减少根和茎中的 K 吸收，显著抑制了番茄的生长。Mel 和 BR 的联合应用通过以下方式减少了 Cd 对番茄的不利影响：（i）减少地上部的 Cd 积累；（ii）提高不同抗氧化剂（SOD、CAT、APX、GR）的活性；（iii）触发与 Cd 液泡隔离相关基因的更高表达（Na/H EXCHANGER、SlNHX1；天然抗性相关巨噬蛋白 6、SlNRAMP6）、Cd 转运和解毒（重金属相关 3、SlHMA3；植物镉抗性 2、SlPCR2）；（iv）改善植物 K 稳态和根和茎中的含量。后一特性与 Cd 胁迫下 K 通透外向整流通道（SlGORK3）基因表达减少以及高亲和力钾转运体 5（SIHAK5）的转录上调有关。Mel 和 BR 的单独应用通过调节抗氧化剂活性、K 吸收、Cd 吸收、从根到茎的转运及其内源含量，表现出对番茄生长和 Cd 耐受性的组织特异性调节。褪黑素本身在改善地上部 Cd 耐受性方面更有效，而油菜素内酯的有益作用在根部更为明显，两者的联合应用对两种组织都有效。综上所述，研究结果表明 Mel 和 BR 对樱桃番茄植株的 Cd 耐受性具有组织特异性调节作用，并证明了 Mel+BR 联合处理作为减少 Cd 积累和减轻其对植物生长负面影响的实用工具的有效性。
