Isolation of salt tolerance related membrane component from mangrove tree

我们前期的研究表明，随着盐度的增加，红树植物根部的萜类化合物含量增加。为此，分析了冲绳红树林中的非皂化脂(NSL)，并特别参考了萜类化合物。通过~(13)&gt；~(13)C-核磁共振和GC-MS谱图分析鉴定了三萜类和植物甾醇类化合物。三萜类和植物甾醇是NSL的主要成分。其中三萜类化合物主要由11个化合物组成，植物甾醇类化合物主要由6个化合物组成。三萜类的主要成分为羽扇豆醇、-香草素和蒲公英醇，植物甾醇的主要成分为-谷甾醇和豆甾醇。红树植物叶片和根的NSL组成具有多样性，表明存在不同的生物合成酶系统。根的萜类成分并不总是与叶的相似，这表明根中的萜类化合物是由原位生物合成产生的，而不是叶的合成物的转运。三萜类化合物在红树根部的分布比例较大，提示了三萜类化合物对红树林的保护作用。利用聚合酶链式反应技术从红树林根部分离得到氧化苦参烯环化酶基因，并将其导入酵母突变株Gil 77中。将OSC基因转化GIL-77后，未见与OSC相关的萜类物质积累。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.