Department of Environmental Science, University of Eastern Finland, FI-70211 Kuopio, Finland.
Tree Physiol. 2011 Dec;31(12):1356-77. doi: 10.1093/treephys/tpr111. Epub 2011 Nov 22.
Plants produce a variety of volatile organic compounds (VOCs). Under abiotic and biotic stresses, the number and amount of produced compounds can increase. Due to their long life span and large size, trees can produce biogenic VOCs (BVOCs) in much higher amounts than many other plants. It has been suggested that at cellular and tree physiological levels, induced production of VOCs is aimed at improving plant resistance to damage by reactive oxygen species generated by multiple abiotic stresses. In the few reported cases when biosynthesis of plant volatiles is inhibited or enhanced, the observed response to stress can be attributed to plant volatiles. Reported increase, e.g., in photosynthesis has mostly ranged between 5 and 50%. A comprehensive model to explain similar induction of VOCs under multiple biotic stresses is not yet available. As a result of pathogen or herbivore attack on forest trees, the induced production of VOCs is localized to the damage site but systemic induction of emissions has also been detected. These volatiles can affect fungal pathogens and the arrival rate of herbivorous insects on damaged trees, but also act as signalling compounds to maintain the trophic cascades that may improve tree fitness by improved efficiency of herbivore natural enemies. On the forest scale, biotic induction of VOC synthesis and release leads to an amplified flow of BVOCs in atmospheric reactions, which in atmospheres rich in oxides of nitrogen (NOx) results in ozone formation, and in low NOx atmospheres results in oxidation of VOCs, removal in ozone from the troposphere and the resulting formation of biogenic secondary organic aerosol (SOA) particles. I will summarize recent advances in the understanding of stress-induced VOC emissions from trees, with special focus on Populus spp. Particular importance is given to the ecological and atmospheric feedback systems based on BVOCs and biogenic SOA formation.
植物会产生多种挥发性有机化合物（VOCs）。在非生物和生物胁迫下，产生的化合物数量和种类会增加。由于树木寿命长、体型大，因此产生的生物源挥发性有机化合物（BVOCs）比许多其他植物要多得多。有人提出，在细胞和树木生理水平上，VOC 的诱导产生旨在提高植物对多种非生物胁迫产生的活性氧物质造成的损害的抵抗力。在少数报道的植物挥发物生物合成被抑制或增强的情况下，对胁迫的观察反应可以归因于植物挥发物。例如，光合作用的增加大多在 5%至 50%之间。目前还没有一个综合的模型可以解释在多种生物胁迫下 VOC 类似的诱导。由于森林树木受到病原体或食草动物的攻击，VOC 的诱导产生局限于受损部位，但也检测到系统诱导排放。这些挥发性物质可以影响真菌病原体和食草昆虫到达受损树木的速度，但也可以作为信号化合物，维持营养级联，通过提高草食性昆虫天敌的效率来提高树木的适应性。在森林尺度上，生物诱导 VOC 合成和释放导致大气反应中 BVOCs 的放大流动，在富含氮氧化物（NOx）的大气中导致臭氧形成，在低 NOx 大气中导致 VOC 氧化、对流层中臭氧去除以及生物源二次有机气溶胶（SOA）颗粒的形成。我将总结近年来对树木胁迫诱导 VOC 排放的理解进展，特别关注杨树属。特别重视基于 BVOCs 和生物 SOA 形成的生态和大气反馈系统。
