College of Horticulture, Northwest A&F University, Yangling 712100, China.
Key Laboratory of Protected Horticultural Engineering in Northwest, Ministry of Agriculture, Yangling 712100, China.
Int J Mol Sci. 2023 Jun 28;24(13):10781. doi: 10.3390/ijms241310781.
Previous studies found that 5-aminolevulinic acid (ALA) and abscisic acid (ABA) can mitigate damage from adversity by enhancing photosynthesis. However, it is not clear whether they have positive effects on iron utilization and chlorophyll synthesis of tomato seedlings under low-temperature stress. To investigate the possible functional relationship between ABA and ALA and elucidate the possible mechanisms of action of ALA to alleviate low-temperature stress in tomato seedlings, this experiment analyzed the effects of ALA and ABA on chlorophyll synthesis in tomato seedling leaves sprayed with exogenous of ALA (25 mg·L) or ABA (100 µM) under low-temperature stress (8-18 °C/8-12 °C, day/night). The results show that exogenous ALA increased the Fv/Fm of tomato leaves by 5.31% and increased the accumulation of iron and chlorophyll by 101.15% and 15.18%, respectively, compared to the low-temperature treatment alone, and tomato resistance of low-temperature stress was enhanced. Meanwhile, exogenous application of ALA increased the ABA content by 39.43%, and subsequent application of exogenous ABA revealed that tomato seedlings showed similar effects to exogenous ALA under low-temperature stress, with increased accumulation of iron and chlorophyll in tomato seedlings, which eventually increased the maximum photochemical efficiency of PS II. Under low-temperature stress, application of exogenous ABA significantly reduced ALA content, but the expression of key enzyme genes (, , , and ), precursors of chlorophyll synthesis by ALA, was significantly elevated, presumably because the increased activity of these enzymes after external application of ABA accelerated ALA consumption. In conclusion, ABA may crosstalk with ALA to improve the photochemical efficiency and low temperature resistance of tomatoes by regulating chlorophyll synthesis and iron accumulation.
先前的研究发现，5-氨基乙酰丙酸（ALA）和脱落酸（ABA）可以通过增强光合作用来减轻逆境损伤。然而，目前尚不清楚它们在低温胁迫下对番茄幼苗铁利用和叶绿素合成是否有积极影响。为了研究 ABA 和 ALA 之间可能的功能关系，并阐明 ALA 缓解番茄幼苗低温胁迫的可能作用机制，本实验分析了在低温胁迫下（8-18°C/8-12°C，白天/黑夜）外源喷施 ALA（25mg·L）或 ABA（100µM）对番茄幼苗叶片叶绿素合成的影响。结果表明，与单独低温处理相比，外源 ALA 使番茄叶片的 Fv/Fm 提高了 5.31%，铁和叶绿素的积累分别增加了 101.15%和 15.18%，增强了番茄对低温胁迫的抗性。同时，外源 ALA 增加了 ABA 含量 39.43%，随后外源 ABA 的应用表明，番茄幼苗在低温胁迫下表现出与外源 ALA 相似的效果，番茄幼苗中铁和叶绿素的积累增加，最终增加了 PSII 的最大光化学效率。在低温胁迫下，外源 ABA 的应用显著降低了 ALA 含量，但 ALA 合成的关键酶基因（、、、和）和前体的表达显著升高，推测可能是因为 ABA 外源处理后这些酶活性的增加加速了 ALA 的消耗。综上所述，ABA 可能通过调节叶绿素合成和铁积累与 ALA 相互作用，提高番茄的光化学效率和抗低温能力。
