Isolation of salt tolerance related membrane component from mangrove tree

我们前期的研究表明，红树林根系中萜类化合物的含量随盐度的增加而增加。出于这个原因，非皂化脂质（NSL）从冲绳红树林进行了分析，特别提到萜类化合物。通过~ 1HC-NMR和GC-MS分析鉴定了其中的三萜和甾醇<13>。三萜类和植物甾醇类化合物是NSL的主要成分。其中三萜类化合物主要有11个，甾醇类化合物主要有6个。三萜类化合物中主要成分为羽扇豆醇、□-香树脂醇和蒲公英甾醇，植物甾醇中主要成分为□-谷甾醇和豆甾醇。红树林植物的根和叶的NSL组成的多样性，这意味着不同的酶系统的生物合成的发生。根的萜类组成并不总是与叶的萜类组成相似，这表明根中的萜类化合物是通过原位生物合成产生的，而不是从叶中转运的萜类化合物。萜类化合物主要分布在根的外部，表明三萜类化合物在红树林中具有保护作用。采用PCR方法从红树林根中分离氧化角鲨烯环化酶（OSC）基因，并将其转化到OSC缺陷型酵母突变株GIL 77中。用OSC基因转化GIL 77不导致OSC相关萜类化合物的积累。分离的OSC的表达和功能分析正在进行中。

Our previous study showed that the terpenoid concentration of mangrove root increased with salinity. For this reason, nonsaponifiable lipids(NSL) from Okinawan mangroves were analyzed with a special reference to terpenoids. Identifications of the triterpenoids and phytosterols were based on the analysis of ^<13>C-NMR and GC-MS spectra. Triterpenoids and phytosterols comprised the major proportion of NSL. The triterpenoids and phytosterols mainly consisted of 11 and 6 compounds, respectively. The major components were lupeol, □-amyrin and taraxerol for triterpenoids and were □-sitosterol and stigmasterol for phytosterols. The diversity in the NSL composition was noted with mangrove species for both leaves and roots, implying the occurrence of divergent enzyme systems for biosynthesis. Terpenoid compositions of the root are not always similar to that of leaf, suggesting that terpenoids in the root are produced by biosynthesis in situ, not a translocation of the synthate from the leaf. Terpenoids existed in greater proportion in the outer parts of the root, suggesting the protective roles of triterpenoids in mangrove. Oxidosqualene cyclase(OSC) gene was isolated from mangrove root by PCR, introduced into osc-defective yeast mutant GIL 77. Transformation of GIL 77 with OSC gene resulted in no accumulation of the OSC related terpenoids. Expression and functional analysis of the isolated OSC is in progress.