基于转录组和代谢组解析香瓜茄果实类黄酮代谢差异

Analysis of Flavonoid Metabolism in Different Cultivated Pepino Fruits Based on Transcriptome and Metabolome

为了解香瓜茄果实主要类黄酮成分以及不同栽培种间类黄酮物质的代谢差异,以我国当前主栽的淡椭圆形果实(LOF)和甜圆形果实(SRF)2个香瓜茄栽培种类型为对象,对成熟果实进行转录组和代谢组联合分析。结果表明,香瓜茄果实中类黄酮组分共鉴定出9类二级代谢产物,41种三级代谢产物,黄酮醇含量最高。具有显著差异的代谢物有21种,主要分布在黄烷醇类、黄酮碳糖苷等6类二级代谢物质中。LOF的二氢黄酮、黄烷醇类、异黄酮的含量高于SRF,而黄酮醇等其他类黄酮化合物则在SRF中含量较高。RNA-seq分析共鉴定出与类黄酮代谢相关的基因503条,其中类黄酮合成通路上游的苯丙氨酸解氨酶(PAL)、肉桂醇脱氢酶(CAD)、黄烷酮-3-羟化酶(F3H)等关键基因表达在LOF中较SRF均上调,而黄酮醇合成酶基因(FLS)表达则在SRF中高于LOF。根据转录组的结果,4个类黄酮合成酶的表达趋势与RT-PCR的检测结果一致。研究结果表明,在不同香瓜茄资源LOF和SRF中存在大量的类黄酮化合物及其合成酶基因,但不同类黄酮成分及其合成代谢相关酶在不同资源含量均存在差异。

In order to understand the main flavonoids and the key synthase genes related to flavonoids and clarify the differences of flavonoids among different pepino.Combined metabolomic and transcriptomic analyses were carried out with the mature pepino(LOF and SRF)currently main cultivars in China.The results showed that 9 kinds of secondary metabolites and 41 kinds of tertiary metabolites were identified,and the flavonols content was the highest.There were 21 metabolites with significant differences in flavonoid components,which were distributed in 6 secondary metabolites such as flavanols,flavonoid carbonoside.The total content of dihydroflavonol,flavanols and isoflavones was higher in the Light-oval fruit(LOF)than in the Sweet-round fruit(SRF),while other compounds including flavonols were higher in the SRF.A total of 503 genes related to flavonoid synthesis were identified by RNA-seq analysis,the expression of Phenylalanine ammonia-lyase(PAL),Cinnamyl alcohol dehydrogenase(CAD),and Flavanone-3-Hydroxylase(F3H)which were key genes for upstream stage of the whole process of pepino flavonoid synthesis,were all up-regulated in LOF compared to SRF.Flavonol synthase gene expression was consistently higher in SRF than LOF.According to the result of transcriptome,the expressed trend of 4 flavonoid synthases agreed with the testing by the RT-PCR.The results showed that a large number of flavonoid compounds and their synthase genes were present in different cultivars of pepino.However,the content of different flavonoid components and the activities of enzymes related to its assimilation and is varied among different resources.