Physiological significance of terpenoid in the salt tolerance of mangrove trees

本研究旨在探讨萜类化合物在红树林植物耐盐性中的生理意义。我们首先研究了萜类化合物合成酶的mRNA水平与生长条件的盐浓度之间的关系，发现这两个参数之间呈正相关。与我们以前的研究一致，也注意到萜类化合物和盐浓度之间的正相关性。而植物甾醇类化合物则没有这种相关性，这表明萜类化合物在植物耐盐性中的生理功能与植物甾醇不同。此外，还发现萜类化合物基因在酵母中的表达影响了它们在盐胁迫下的生长，表明萜类化合物可以作为脂膜成分发挥作用。最后，为了从红树林植物中分离抗盐胁迫基因，构建了红树植物R.构建了红海榄根，并通过基于聚合酶链反应（PCR）的抑制性消减杂交筛选胁迫相关基因。13个转录本的表达水平显著增加，表明这些基因有助于该植物的耐盐性。其中，两个转录因子和多个类异戊二烯生物合成相关基因是首次从红树林中鉴定出作为盐耐性基因。

Present study aimed to address the physiological significance of terpenoid in salt tolerance of mangrove species. We first examined the relationship between mRNA level of terpenoid synthase and salt concentration of growth conditions, and found positive correlation between these two parameters. Consistent with our previous study, a positive correlation between terpenoid and salt concentration was also noted. These correlations were not observed for phytosterols, which suggested that the physiological function of terpenoid in salt tolerance differed from that of phytosterol. It was also found that expression of terpenoid genes in yeast affected their growth under salinity stress suggesting that terpenoid can function as lipid membrane constituent. Finally, To isolate anti-salt stress genes from mangrove plants, a cDNA library of R. stylosa roots was constructed and screened for stress-related genes by polymerase chain reaction (PCR)-based suppressive subtractive hybridization. Significantly increased expression levels were confirmed for 13 transcripts, which suggest that these genes contribute to the salt tolerance of this plant. Among them, two transcription factors and several genes involved in isoprenoid biosynthesis were identified from mangrove trees as salt tolerance genes for the first time.