遮阴对柠檬香茅类黄酮及其合成酶基因差异表达研究

Effects of Shading on Secondary Metabolites and Their Synthase Genes of Flavonoid in Cymbopogon citratus

摘要:

为了解柠檬香茅(Cymbopogon citratu)中类黄酮及其合成酶基因信息，以阳光直射及遮阴环境下生长的柠檬香茅嫩叶为材料，进行代谢组、转录组结合qRT-PCR验证分析。结果表明，柠檬香茅中含有11类共69种黄酮化合物，其中芦丁、去甲基托罗沙黄酮、紫云英苷及葡萄糖醇等类黄酮化合物在遮阴环境下相对含量显著降低；类黄酮生物合成涉及10类酶54个基因，其中类黄酮3'羟化酶(c99177.1)等4个酶基因在遮阴环境下相对表达量显著降低，而异黄酮合成酶(c51975.0)等6个酶基因相对表达量正好相反；其中5个类黄酮合成酶基因在光照及遮阴柠檬香茅中的上下调表达趋势与转录组测序结果中FPKM值变化一致，而二者检测结果中差异表达倍数存在差异。遮阴使柠檬香茅中大多黄酮类化合物相对含量降低，而其合成酶基因上下调表达趋势规律不明显。

Abstract:

In order to understand the gene information of flavonoids and their synthase in Cymbopogon citratu, the metabolome, transcriptome and qRT-PCR were studied by using young leaves of C. citratu growing in sunlight and shade. The results showed that C. citratus contained 69 flavonoids belonging to 11 kinds. The contents of flavonoids, such as rutin, demethyltorosaflavone, astragalin and glucosylorobol etc., decreased under shade environment. The flavonoid biosynthesis involved 10 kinds of enzymes encoded by 54 genes. The expressions of 4 genes, such as F3'H (c99177.1), decreased significantly under shade environment, while those of 6 genes, such as FSI (c51975.0) etc., were opposite. The up-or down-regulation expression trend of 5 flavonoid synthase genes under light and shading was consistent with the change of FPKM in transcriptome sequencing, however, there was difference in the differential expression multiples between the two methods. Therefore, Shading could decrease the relative content of flavonoid in C. citratus, but the relative expression of synthetase genes was irregular whether up or down regulation.