Melatonin antagonizes ABA action to promote seed germination by regulating Ca2+ efflux and H2O2 accumulation
Melatonin antagonizes ABA action to promote seed germination by regulating Ca2+ efflux and H2O2 accumulation
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DOI：
10.1016/j.plantsci.2020.110761
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发表时间：
2021-02-01
期刊：
影响因子：
5.2
通讯作者：
Zhang, Xian
中科院分区：
文献类型：
--
作者：
Li, Hao;Guo, Yanliang;Zhang, Xian
种子萌发是植物生活史中的一个重要阶段，对植物的建立起着至关重要的作用。褪黑素已被证明在各种环境胁迫下促进种子萌发；然而，其机制仍未得到很大程度的了解。在此，我们报道了褪黑素通过调节脱落酸(ABA)和赤霉酸(GA(3))的平衡来拮抗ABA促进种子萌发的作用。转录分析表明，褪黑素的这种作用与钙离子和氧化还原信号有关。褪黑素可诱导细胞内钙外流，并上调空泡H+/钙逆向转运体3(CAX3)的表达。在拟南芥中，AtCAX3缺失表现为钙外流减少。在ABA胁迫下，抑制甜瓜种子和拟南芥突变体AtCAX3的Ca~(2+)外流可抑制褪黑激素诱导的萌发。在ABA胁迫下，褪黑素增加了H_2O_2的积累，H_2O_2处理降低了ABA/GA(3)比值，促进了种子萌发。然而，完全抑制过氧化氢的积累破坏了褪黑素诱导的ABA和GA(3)平衡和种子萌发。我们的研究揭示了一种新的调节机制，即褪黑素抵消ABA诱导种子萌发，主要涉及CAX3介导的钙离子外流和过氧化氢积累，进而通过促进ABA的分解代谢和/或GA(3)的生物合成来调节ABA和GA(3)的平衡。
Seed germination is a vital stage in the plant life-cycle that greatly contributes to plant establishment. Melatonin has been shown to promote seed germination under various environmental stresses; however, the mechanism remains largely underexplored. Here, we reported that melatonin antagonized abscisic acid (ABA) to promote seed germination by regulating ABA and gibberellic acid (GA(3)) balance. Transcriptomic analysis revealed that such a role of melatonin was associated with Ca2+ and redox signaling. Melatonin pretreatment induced Ca2+ efflux accompanied by an up-regulation of vacuolar H+/Ca2+ antiporter 3 (CAX3). AtCAX3 deletion in Arabidopsis exhibited reduced Ca2+ efflux. Inhibition of Ca2+ efflux in the seeds of melon and Arabidopsis mutant AtCAX3 compromised melatonin-induced germination under ABA stress. Melatonin increased H2O2 accumulation, and H2O2 pretreatment decreased ABA/GA(3) ratio and promoted seed germination under ABA stress. However, complete inhibition of H2O2 accumulation abolished melatonin-induced ABA and GA(3) balance and seed germination. Our study reveals a novel regulatory mechanism in which melatonin counteracts ABA to induce seed germination that essentially involves CAX3-mediated Ca2+ efflux and H2O2 accumulation, which, in turn, regulate ABA and GA(3) balance by promoting ABA catabolism and/or GA(3) biosynthesis.