茉莉酸甲酯对马尾松萜类合成酶活性及其细胞化学定位的影响
摘要： 马尾松（Pinus massoniana）是我国南方生态建设与造林用材的主要树种，为了揭示马尾松抗虫机理尤其是诱导抗虫性的分子机制，该研究以马尾松幼苗为材料，通过外源喷施茉利酸甲酯（MeJA），分析了处理与对照间植株针叶显微结构、萜类合成酶活性及其细胞化学定位的变化。结果表明：在0.2 mmol·L-1 MeJA处理下马尾松植株松针中萜类物质，尤其是单萜、二萜的相对含量增加，马尾松毛虫拒食性明显，诱导抗性增强。显微观测中，针叶叶肉细胞内树脂道分泌物增加，叶绿体数目减少，但叶绿体体积增大，叶绿体片层结构增加。MeJA处理4周后，针叶中萜类合成酶活性增加，通过电镜酶细胞化学观察，膜系统尤其是叶绿体膜上萜类合成酶活性定位明显增强。这说明MeJA诱导的马尾松诱导抗性可能与改变的叶绿体结构及绿色质体萜类合成酶活性密切相关。
关键词： 马尾松， 诱导抗性， 细胞化学， 萜类物质
中图分類号： S722.8文献标识码： A文章编号： 1000-3142（2018）07-0876-10
Abstract： Pinus massoniana is one of the most important tree species for afforestation in South China， and it is of great economic value and ecological benefit. This study aimed to reveal the cytological basis in relation to induced resistance during the biosynthesis of terpenoids in P. massoniana， and provide the guide for the further research on molecular mechanism of induced insect resistance in P. massoniana. In the illumination incubator with strictly controlled conditions of light and temperature， variations of microscopic structure， terpenoid synthetase activity and its cytochemical localization of needles were investigated in P. massoniana seedlings treated by exogenous jasmonates. The results showed that there were increases in the relative contents of terpenoids， especially， in those of monoterpenoids and diterpenoids， and the antifeedant of Dendrolimus punctatus against needles in Pinus massoniana seedlings was increased following the treatment of 0.2 mmol·L-1 MeJA， which indicated that the induced resistance of P. massoniana were strengthened. For the variations of anatomical structure， secretions of resin canal were enhanced， the number of chloroplast was reduced， the volume of it was increased， and the thylakoid of it was enhanced in the needles of P. massoniana seedlings. The activity of terpenoid synthetase was increased after four weeks of MeJA treatment. The localization of terpenoid synthetase activity was remarkably increased from membrane system， especially， from chloroplast membrane in the needles of P. massoniana seedlings using the method for electron microscopic cytochemistry of enzyme. This implies that the induced resistance is closely related to the changed chloroplast structure and terpenoid synthetase activity in green plastids in P. massaniana exposed to MeJA treatment.
Key words： Pinus massoniana， induced resistance， cytochemistry， terpenoid
马尾松（Pinus massoniana）是我国造林用材与生态建设的主要造林树种，人工林面积达1 200万hm2，居全国乔木树种的首位，其利用价值高，生态、经济与社会效益显著，具有广阔的推广应用前景（丁贵杰等，2006）。马尾松虫害严重，发生面积最大，在我国周期性暴发成灾，制约了马尾松产业的高效发展（戈峰等，2002）。目前，利用马尾松组成抗性通过良种选育在虫害防治方面取得了显著成效，但在马尾松诱导抗性方面的报道仍鲜少见，其抗虫机制仍不清楚（胡少波等，1988；马尾松抗松毛虫抗性研究组，1990；孙艳丽，2010）。在马尾松的诱导抗性机理研究中，许多学者发现马尾松抗虫性与萜类物质有关（胡少波等，1988；胡永建，2010）。