Key message

Supplying Ca²⁺ and MT can be a key approach to elucidating the diverse physiological and biochemical mechanisms of plant growth, development, and resistance under environmental stresses.

Abstract

Although many studies have demonstrated the positive effects of exogenous melatonin (MT) under diverse stresses, most are related to crops and few have focused on woody trees. Moreover, the best outcomes related to the positive influence of MT on plants under chilling stress were obtained by applying MT alone. Thus, this work aimed to boost the strength of MT in the woody plant Dalbergia odorifera under cold stress through combination with the signaling molecule Ca²⁺, which has a major role in plant defense against abiotic stresses. Results showed that in D. odorifera seedlings, exogenous MT and Ca²⁺ application improved growth traits and relieved injuries, whereas chilling stress caused injuries and reduced growth. Exogenous MT and Ca²⁺increased photosynthetic activity and compatible solute (proline, glucose, fructose, and sucrose) accumulation. Starch degradation induced by chilling stress was significantly reduced in seedlings under treatment with MT combined with Ca²⁺. Furthermore, in D. odorifera seedlings, relative conductivity, lipid peroxidation, and reactive oxygen species were elevated under cold stress, whereas these indexes were strongly decreased by exogenous MT and Ca²⁺. Exogenous MT and Ca²⁺ enhanced the antioxidant activities against chilling stress. In addition, in D. odorifera seedlings under cold stress, exogenous MT and Ca²⁺ strongly elevated the levels of the phytohormones gibberellin (GA₃) and auxin (IAA) but decreased those of abscisic acid (ABA) was decreased. The IAA and GA₃ contents were increased respectively by 17.34% and 22.47% in seedlings treated with MT-Ca²⁺ compared to MT treatment. Meanwhile, the ABA content was decreased by 44.80% in MT-Ca²⁺-treated seedlings compared to MT treatment. In conclusion, exogenous MT and Ca²⁺ improved chilling stress tolerance in D. odorifera seedlings by regulating phytohormones, osmolytes, and antioxidant activities.

中文翻译：

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外源褪黑素与Ca 2+的耦合缓解了黄檀中的冷胁迫

关键信息

提供Ca ²⁺和MT可能是阐明环境胁迫下植物生长，发育和抗性的多种生理和生化机制的关键方法。

抽象的

尽管许多研究表明外源褪黑素（MT）在多种压力下均具有积极作用，但大多数与农作物有关，很少关注木本植物。此外，单独施用MT可获得与MT对低温胁迫下植物的积极影响相关的最佳结果。因此，这项工作旨在通过与信号分子Ca ^2+的组合来增强冷胁迫下木本植物黄檀中MT的强度，该信号分子在植物对抗非生物胁迫中起主要作用。结果表明，在D. odoruma幼苗中，外源MT和Ca ²⁺施用可改善生长特性并减轻伤害，而寒冷的压力可导致伤害并减少生长。外源MT和Ca ²⁺增加了光合作用活性和相容性溶质（脯氨酸，葡萄糖，果糖和蔗糖）的积累。MT ⁺ Ca ²⁺处理对幼苗低温胁迫诱导的淀粉降解显着降低。此外，在D. odorifera幼苗中，冷胁迫下相对电导率，脂质过氧化和活性氧种类均升高，而外源MT和Ca ²⁺则使这些指标大大降低。外源MT和Ca ²⁺增强了抗寒应激的抗氧化活性。另外，在D. odorifera幼苗在冷胁迫下，外源MT和Ca ²⁺强烈提高了植物激素赤霉素（GA ₃）和生长素（IAA）的水平，但降低了脱落酸（ABA）的水平。与MT处理相比，MT-Ca ²⁺处理的幼苗的IAA和GA ₃含量分别增加了17.34％和22.47％。同时，与MT处理相比，MT-Ca ²⁺处理的幼苗中的ABA含量降低了44.80％。总之，外源MT和Ca ²⁺通过调节植物激素，渗透压和抗氧化活性，提高了香D幼苗的耐冷胁迫能力。