Raw data for all figures (including the data for the supplementary figures and tables) from Volatile-mediated between-plant communication in Scots pine and the effects of elevated ozone

Conifers are dominant tree species in boreal forests, but are susceptible to attack by bark beetles. Upon bark beetle attack, conifers release substantial quantities of volatile organic compounds known as herbivore-induced plant volatiles (HIPVs). Earlier studies of broadleaved plants have shown that HIPVs provide information to neighbouring plants, which may enhance their defenses. However, the defence responses of HIPV-receiver plants have not been described for conifers. Here we advance knowledge of plant–plant communication in conifers by documenting a suite of receiver-plant responses to bark-feeding-induced volatiles. Scots pine seedlings exposed to HIPVs were more resistant to subsequent weevil feeding and received less damage. Receiver plants had both induced and primed volatile emissions and their resin ducts had an increased epithelial cell (EC) mean area and an increased number of cells located in the second EC layer. Importantly, HIPV exposure increased stomatal conductance and net photosynthesis rate of receiver plants. Receiver-plant responses were also examined under elevated ozone conditions and found to be significantly altered. However, the final defense outcome was not affected. These findings demonstrate that HIPVs modulate conifer metabolism through responses spanning photosynthesis and chemical defense. The responses are adjusted under ozone stress, but the defense benefits remain intact.

针叶树（Conifers）是北方森林中的优势树种，但易受树皮甲虫（bark beetles）的侵袭。当遭受树皮甲虫侵袭时，针叶树会释放大量挥发性有机化合物，即植食性昆虫诱导植物挥发物（herbivore-induced plant volatiles，HIPVs）。此前针对阔叶植物的研究表明，HIPVs可向邻近植株传递信息，从而增强其防御能力。但目前尚未有关于针叶树的HIPV接收植株防御反应的相关报道。本研究通过记录针叶树接收取食树皮诱导挥发物后的一系列植株响应，拓展了人们对针叶树植株间通讯的认知。暴露于HIPVs环境下的欧洲赤松幼苗，对后续象甲取食的抗性更强，受损伤程度更低。接收植株同时出现了诱导型与启动型的挥发物释放，且其树脂道的上皮细胞（epithelial cell，EC）平均面积增大，第二层EC层的细胞数量也有所增加。值得注意的是，HIPV暴露可提升接收植株的气孔导度与净光合速率。本研究还在高臭氧环境下检测了接收植株的响应，发现其发生了显著变化，但最终的防御效果并未受到影响。上述研究结果表明，HIPVs可通过调控光合与化学防御相关的响应来调节针叶树的代谢过程。虽然在臭氧胁迫下这些响应会发生调整，但防御益处依然得以保留。