Kanagendran Arooran, Pazouki Leila, Niinemets Ülo
Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Kreutzwaldi 1, Tartu 51014, Estonia.
Estonian Academy of Sciences, Kohtu 6, 10130 Tallinn, Estonia.
Environ Exp Bot. 2018 Jan;145:21-38. doi: 10.1016/j.envexpbot.2017.10.012.
Both ozone and wounding constitute two key abiotic stress factors, but their interactive effects on plant constitutive and stress-elicited volatile (VOC) emissions are poorly understood. Furthermore, the information on time-dependent modifications in VOC release during recovery from a combined stress is very limited. We studied the modifications in photosynthetic characteristics and constitutive and stress-induced volatile emissions in response to single and combined applications of acute ozone (4, 5, and 6 ppm) and wounding treatments through recovery (0.5-75 h) in a constitutive isoprene and mono- and sesquiterpene emitter . Overall, the photosynthetic characteristics were surprisingly resistant to all ozone and wounding treatments. Constitutive isoprene emissions were strongly upregulated by ozone and combined ozone and wounding treatments and remained high through recovery phase, but wounding applied alone reduced isoprene emission. All stress treatments enhanced emissions of lipoxygenase pathway volatiles (LOX), mono- and sesquiterpenes, saturated aldehydes (C7-C10), benzenoids, and geranylgeranyl diphosphate (GGDP) pathway volatiles. Once elicited, GGDP volatile, saturated aldehyde and benzenoid emissions remained high through the recovery period. In contrast, LOX emissions, and total mono- and sesquiterpene emissions decreased through recovery period. However, secondary rises in total sesquiterpene emissions at 75 h and in total monoterpenes at 25-50 h were observed. Overall, acute ozone and wounding treatments synergistically altered gas exchange characteristics and stress volatile emissions. Through the treatments and recovery period, stomatal ozone uptake rate and volatile emission rates were poorly correlated, reflecting possible ozone-scavenging effect of volatiles and thus, reduction of effective ozone dose and elicitation of induced defense by the acute ozone concentrations applied. These results underscore the important role of interactive stresses on both constitutive and induced volatile emission responses.
臭氧和机械损伤均构成两个关键的非生物胁迫因子，但其对植物组成型和胁迫诱导型挥发性有机化合物（VOC）排放的交互作用却鲜为人知。此外，关于复合胁迫恢复过程中VOC释放随时间变化的信息非常有限。我们研究了在一个组成型异戊二烯、单萜和倍半萜排放植物中，通过恢复阶段（0.5 - 75小时），响应急性臭氧（4、5和6 ppm）和机械损伤单一及复合处理时，光合特性以及组成型和胁迫诱导型挥发性排放的变化。总体而言，光合特性对所有臭氧和机械损伤处理均表现出惊人的抗性。组成型异戊二烯排放受到臭氧、臭氧与机械损伤复合处理的强烈上调，并且在恢复阶段一直保持在较高水平，但单独施加机械损伤会降低异戊二烯排放。所有胁迫处理均增强了脂氧合酶途径挥发性有机化合物（LOX）、单萜和倍半萜、饱和醛（C7 - C10）、苯类化合物以及香叶基香叶基二磷酸（GGDP）途径挥发性有机化合物的排放。一旦被诱导，GGDP挥发性有机化合物、饱和醛和苯类化合物的排放在恢复期间一直保持在较高水平。相比之下，LOX排放以及单萜和倍半萜的总排放量在恢复期间下降。然而，在75小时时观察到倍半萜总排放量的二次上升，在25 - 50小时时观察到单萜总排放量的二次上升。总体而言，急性臭氧和机械损伤处理协同改变了气体交换特性和胁迫挥发性排放。在处理和恢复期间，气孔对臭氧的吸收速率与挥发性排放速率相关性较差，这反映了挥发性有机化合物可能具有的臭氧清除作用，从而降低了有效臭氧剂量，并通过所施加的急性臭氧浓度引发诱导防御。这些结果强调了交互胁迫在组成型和诱导型挥发性排放响应中的重要作用。
