Induced defence of pine (Pinus sylvestris) against egg deposition by sawflies: Characterisation of the elicitor

植食性昆虫产卵能诱导植物的防御反应。松树（Pinus sylvestris）改变其萜类化合物的气味，以响应卵沉积的食草性松叶蜂。产卵诱导的松树挥发物吸引卵寄生蜂杀死卵，从而保护松树免受叶蜂幼虫取食的危害。这种由昆虫卵沉积诱导的间接植物防御的激发子已知位于叶蜂输卵管分泌物中，该分泌物将卵附着在松针上。卵沉积对植物挥发性模式的影响可以通过将孤立的输卵管分泌物应用于（无卵）松针来模拟。用蛋白酶处理分泌物会破坏其诱导活性，从而表明诱导子具有蛋白质性质。本研究旨在分离和鉴定松叶蜂输卵管分泌物中的诱导子。此外，我们希望获得有关交配对激发子活性影响的信息。最后，为了阐明该激发子的种特异性，我们将对与D. pini和寻找激发子同系物。

Egg deposition by herbivorous insects can induce defensive responses in plants. Pine (Pinus sylvestris) changes its terpenoid odour in response to egg deposition by herbivorous pine sawflies. The oviposition-induced pine volatiles attract egg parasitoids killing the eggs, thus protecting pine from damage by sawfly larval feeding. The elicitor of this indirect plant defence induced by insect egg deposition is known to be located in sawfly oviduct secretion which is attaching the eggs to pine needles. The effect of egg deposition on the plant´s volatile pattern can be mimicked by application of isolated oviduct secretion onto (egg-free) pine needles. Treatment of secretion with a protease destroys its inducing activity, thus indicating a proteinaceous character of the elicitor. This project focuses on the isolation and identification of the elicitor present in oviduct secretion of the pine sawfly Diprion pini. Furthermore, we want to gain information on the effect of mating on elicitor activity. Finally, in order to elucidate the sawfly species specificity of this elicitor, we will chemically analyse oviduct secretion of species closely related to D. pini and search for elicitor homologs.