Jasmonates (JAs) play a key role in the regulation of growth and the defense response to environmental stresses. JAs inhibit plant growth and promote defense response. However, their roles in desert halophyte in the response to salt stress remain poorly understood. The effects of the combination of methyl jasmonate (MeJA) and NaCl treatment (the 'MeN' condition) on the growth regulation and defense response of Nitraria tangutorum seedlings were investigated. Compared with NaCl treatment alone, exogenous MeJA aggravated the growth inhibition of seedlings by antagonizing to growth-related hormones and suppressing the transcript levels of these hormones-responsive genes, including gibberellin (GA)-responsive NtPIF3, NtGAST1, NtGSAT4, and cytokinin (CYT)-responsive NtARR1, NtARR11, NtARR12. Meanwhile, exogenous MeJA enhanced defense response and alleviated the stress damage by increasing antioxidase activity and antioxidant content, accumulating more osmolytes, maintaining lower Na+ /K+ ratios in shoots and higher Na+ efflux rates in roots of plants. In addition, exogenous MeJA increased the contents of endogenous JA and ABA, and the transcript levels of genes involved in their biosynthesis and responsiveness, thereby further regulating the transcript levels of defense response genes. These findings suggest that exogenous MeJA increases salt stress-induced growth inhibition and prioritizes the defensive responses (e.g. antioxidant defense, osmotic adjustment, and ion homeostasis) of N. tangutorum. These effects may be related to the amplification of jasmonic acid (JA) and abscisic acid (ABA) signals.

中文翻译：

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外源茉莉酸甲酯促进盐胁迫诱导的生长抑制并优先考虑 Nitraria tangutorum Bobr 的防御反应

茉莉酸 (JA) 在生长调节和对环境压力的防御反应中发挥着关键作用。JA 抑制植物生长并促进防御反应。然而，它们在沙漠盐生植物对盐胁迫的反应中的作用仍然知之甚少。研究了茉莉酸甲酯 (MeJA) 和 NaCl 处理（“MeN”条件）的组合对 Nitraria tangutorum 幼苗的生长调节和防御反应的影响。与单独的 NaCl 处理相比，外源性 MeJA 通过拮抗生长相关激素并抑制这些激素反应基因的转录水平，包括赤霉素（GA）反应性 NtPIF3、NtGAST1、NtGSAT4 和细胞分裂素（CYT），从而加重了幼苗的生长抑制。 )-响应 NtARR1、NtARR11、NtARR12。同时，外源性MeJA通过增加抗氧化酶活性和抗氧化剂含量，积累更多渗透物，维持较低的芽中Na + /K + 比率和较高的植物根部Na + 流出率来增强防御反应并减轻胁迫损伤。此外，外源性 MeJA 增加了内源性 JA 和 ABA 的含量，以及参与其生物合成和反应的基因的转录水平，从而进一步调节防御反应基因的转录水平。这些发现表明外源性 MeJA 增加了盐胁迫诱导的生长抑制，并优先考虑了 N. tangutorum 的防御反应（例如抗氧化防御、渗透调节和离子稳态）。这些效应可能与茉莉酸 (JA) 和脱落酸 (ABA) 信号的放大有关。