Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Kreutzwaldi 1, 51006 Tartu, Estonia.
College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China.
Int J Mol Sci. 2020 Feb 4;21(3):1018. doi: 10.3390/ijms21031018.
Treatment by volatile plant hormone methyl jasmonate (MeJA) leads to release of methanol and volatiles of lipoxygenase pathway (LOX volatiles) in a dose-dependent manner, but how the dose dependence is affected by stomatal openness is poorly known. We studied the rapid (0-60 min after treatment) response of stomatal conductance (), net assimilation rate (), and LOX and methanol emissions to varying MeJA concentrations (0.2-50 mM) in cucumber () leaves with partly open stomata and in leaves with reduced due to drought and darkness. Exposure to MeJA led to initial opening of stomata due to an osmotic shock, followed by MeJA concentration-dependent reduction in , whereas initially decreased, followed by recovery for lower MeJA concentrations and time-dependent decline for higher MeJA concentrations. Methanol and LOX emissions were elicited in a MeJA concentration-dependent manner, whereas the peak methanol emissions (15-20 min after MeJA application) preceded LOX emissions (20-60 min after application). Furthermore, peak methanol emissions occurred earlier in treatments with higher MeJA concentration, while the opposite was observed for LOX emissions. This difference reflected the circumstance where the rise of methanol release partly coincided with MeJA-dependent stomatal opening, while stronger stomatal closure at higher MeJA concentrations progressively delayed peak LOX emissions. We further observed that drought-dependent reduction in ameliorated MeJA effects on foliage physiological characteristics, underscoring that MeJA primarily penetrates through the stomata. However, despite reduced , dark pretreatment amplified stress-volatile release upon MeJA treatment, suggesting that increased leaf oxidative status due to sudden illumination can potentiate the MeJA response. Taken together, these results collectively demonstrate that the MeJA dose response of volatile emission is controlled by stomata that alter MeJA uptake and volatile release kinetics and by leaf oxidative status in a complex manner.
用挥发性植物激素茉莉酸甲酯（MeJA）处理会导致甲醇和脂氧合酶途径挥发物（LOX 挥发物）以剂量依赖的方式释放，但气孔开度如何影响剂量依赖性尚不清楚。我们研究了在部分开放气孔的黄瓜（）叶片和由于干旱和黑暗导致气孔开度降低的叶片中，气孔导度（）、净同化率（）和 LOX 及甲醇排放对不同 MeJA 浓度（0.2-50mM）的快速（处理后 0-60 分钟）响应。MeJA 处理导致气孔初始开放，这是由于渗透压冲击，随后 MeJA 浓度依赖性降低，而最初降低，随后较低 MeJA 浓度恢复，较高 MeJA 浓度时间依赖性下降。甲醇和 LOX 排放以 MeJA 浓度依赖性的方式被激发，而甲醇排放的峰值（MeJA 处理后 15-20 分钟）先于 LOX 排放（处理后 20-60 分钟）。此外，较高 MeJA 浓度处理中的甲醇排放峰值更早出现，而 LOX 排放则相反。这种差异反映了这样一种情况，即甲醇释放的增加部分与 MeJA 依赖性的气孔开放同时发生，而在较高 MeJA 浓度下更强的气孔关闭逐渐延迟了 LOX 排放的峰值。我们进一步观察到，干旱依赖性的降低改善了 MeJA 对叶片生理特征的影响，这强调了 MeJA 主要通过气孔渗透。然而，尽管减少，黑暗预处理在 MeJA 处理时放大了应激挥发物的释放，这表明由于突然光照引起的叶片氧化状态增加可以增强 MeJA 的反应。综上所述，这些结果共同表明，挥发性排放的 MeJA 剂量反应受气孔控制，气孔以复杂的方式改变 MeJA 吸收和挥发性释放动力学以及叶片氧化状态。
