遮阴对柠檬香茅中萜类化合物及其合成酶基因影响研究

Effects of Shading on the Production and Synthase Genes of Terpenoids in Cymbopogon citratus

摘要:

为获取柠檬香茅(Cymbopogon citratus)中萜类化合物及其合成酶基因信息，以正常生长及遮阴下的柠檬香茅嫩叶为材料，进行代谢组学和转录组学结合qRT-PCR验证分析。代谢组分析结果表明，柠檬香茅所含萜类共23种，包括单萜4种、倍半萜4种、二萜8种、三萜3种和四萜4种。在遮阴下，柠檬香茅的二萜类银杏内酯C和四萜类虾青素相对含量更高。转录组测序结果表明，单萜生物合成涉及4类合成酶的24个基因，二萜生物合成涉及11类合成酶的49个基因，倍半萜和三萜生物合成涉及12类合成酶的58个基因，其中6类合成酶的8个基因在遮阴下的相对表达量显著提高，而前萘二烯加氧酶(c64786.0)基因正好相反。qRT-PCR分析表明，遮阴下4个FPKM值差异明显的萜类合成酶基因表达的变化趋势与转录组测序结果一致，但不同合成酶基因的差异表达量存在差异。因此，柠檬香茅所含4类共23种萜类化合物由27类合成酶共131个基因编码而来，不同光照强度影响9个合成酶基因的表达和2种萜类化合物含量。

Abstract:

In order to obtain the information of terpenoids and their synthase genes of Cymbopogon citratus, the changes in the transcriptome and metabolome of young leaves under light and shade were studied, and the expression of terpenoid synthase genes was confirmed by qRT-PCR. Metabolomic analysis showed that C. citratus contained 23 terpenes, including 4 monoterpenes, 4 sesquiterpenes, 8 diterpenes, 3 triterpenes and 4 tetraterpenes. The relative contents of ginkgolide C and astaxanthin under shade was higher than those under light. According to transcriptome sequencing, there were 24, 49 and 58 genes encoding 4, 11 and 12 synthases involved monoterpene, diterpene and sesquiterpene and triterpene biosynthesis pathway, respectively, in which the relative expression of 8 genes encoding 6 synthetases significantly increased under shade, but that of premnaspirodiene oxygenase gene was just reverse. The expression patterns of four terpenoid synthase genes with significant difference FPKM values under shading by qRT-PCR was consistent with the transcriptome sequencing results, however, the differential expression of different synthase genes were different. Therefore, it was suggested that C. citratus contains 23 terpenoids in 4 categories catalyzed by 27 synthetases, which are encoded by 131 genes, and light intensity affects the relative content of 2 terpenoids and the expression of 9 synthetase genes.