Molecular Signaling Laboratory, Department of Chemistry, Seoul National University, Seoul, Korea.
Plant Signal Behav. 2010 Dec;5(12):1534-6. doi: 10.4161/psb.5.12.13159. Epub 2010 Dec 1.
Potential roles of salicylic acid (SA) on seed germination have been explored in many plant species. However, it is still controversial how SA regulates seed germination, mainly because the results have been somewhat variable, depending on plant genotypes used and experimental conditions employed. We found that SA promotes seed germination under high salinity in Arabidopsis. Seed germination of the sid2 mutant, which has a defect in SA biosynthesis, is hypersensitive to high salinity, but the inhibitory effects are reduced in the presence of physiological concentrations of SA. Abiotic stresses, including high salinity, impose oxidative stress on plants. Endogenous contents of H(2)O(2) are higher in the sid2 mutant seeds. However, exogenous application of SA reduces endogenous level of reactive oxygen species (ROS), indicating that SA is involved in plant responses to ROS-mediated damage under abiotic stress conditions. Gibberellic acid (GA), a plant hormone closely associated with seed germination, also reverses the inhibitory effects of high salinity on seed germination and seedling establishment. Under high salinity, GA stimulates SA biosynthesis by inducing the SID2 gene. Notably, SA also induces genes encoding GA biosynthetic enzymes. These observations indicate that SA promotes seed germination under high salinity by modulating antioxidant activity through signaling crosstalks with GA.
水杨酸（SA）在种子萌发中的潜在作用在许多植物物种中得到了探索。然而，SA 如何调节种子萌发仍然存在争议，主要是因为结果因所使用的植物基因型和实验条件而异。我们发现 SA 可促进拟南芥在高盐条件下的种子萌发。SA 生物合成缺陷的 sid2 突变体的种子对高盐敏感，但在生理浓度的 SA 存在下，抑制作用降低。非生物胁迫，包括高盐，对植物造成氧化应激。过氧化氢（H2O2）的内源性含量在 sid2 突变体种子中较高。然而，外源应用 SA 降低了内源性活性氧（ROS）的水平，表明 SA 参与了植物对 ROS 介导的非生物胁迫条件下损伤的反应。赤霉素（GA），一种与种子萌发密切相关的植物激素，也能逆转高盐对种子萌发和幼苗建立的抑制作用。在高盐条件下，GA 通过诱导 SID2 基因来刺激 SA 生物合成。值得注意的是，SA 也诱导编码 GA 生物合成酶的基因。这些观察结果表明，SA 通过与 GA 的信号串扰来调节抗氧化活性，从而促进高盐条件下的种子萌发。
