五指毛桃(Ficus hirta)是一种重要的药食两用植物资源, 但叶片形态变异较大。为揭示其叶形差异与主要活性物质含量间的关系, 本研究采用LC-MS/MS测定全缘型(EL)、浅裂型(LL)和五指深裂型(PDL)3种叶形五指毛桃根中补骨脂素和佛手柑内酯含量, 并进一步利用转录组测序技术探索其含量差异形成的潜在分子机制。结果表明, PDL的补骨脂素含量显著高于EL和LL; EL的佛手柑内酯含量显著高于LL, 但与PDL没有显著性差异。测序共获得60.9 Gb clean reads, 组装获得46 194个unigenes, 同源序列比对显示五指毛桃与川桑(Morus notabilis)的同源性最高。从PDL_vs_EL、PDL_vs_LL和LL_vs_EL比较组分别筛选出2 355、2 067和2 001个DEGs, 它们主要富集在苯丙烷生物合成、淀粉和蔗糖代谢、植物-病原体相互作用等通路上, 其中苯丙烷生物合成通路和植物-病原体相互作用通路可能是五指毛桃主要活性物质生物合成与积累的重要通路。该研究初步探讨了五指毛桃不同叶形与主要活性物质积累间的关系、扩展了五指毛桃转录组数据库, 为进一步利用不用叶形五指毛桃种质资源及品质育种提供参考依据。

INTRODUCTION: Ficus hirta Vahl is a common Chinese herbal medicine and edible plant resource in the Lingnan area of China. It contains coumarins, flavonoids and other chemical compounds, which have antioxidant, anti-inflammatory, antibacterial, antiviral and antitumor effects. However, F. hirta exhibits significant morphological variation in leaf shapes due to its high genetic diversity. 

RATIONALE: To investigate the relationship between the leaf shape differences and the contents of major active compounds, herein, LC-MS/MS was performed to determine the contents of psoralen and bergapten in F. hirta roots from three different leaf shapes (entirc leaf, EL; lobed leaf, LL; Palmately deeply leaf, PDL), and transcriptome sequencing was further employed to explore the potential molecular mechanisms underlying these contents variations. 

RESULTS: Results showed that PDL exhibited significantly higher psoralen content compared to EL and LL, while EL with significantly higher bergapten content than that in LL, but no significant difference was observed between EL and PDL. A total of 60.9 Gb clean reads were obtained, and 46 194 unigenes were assembled. F. hirta had the highest homology with Morus notabilis, according to the homologous sequencing alignment. 2 355, 2 067 and 2 001 differentially expressed genes (DEGs) were screened from three comparison groups PDL_vs_EL, PDL_vs_LL, and LL_vs_EL, respectively. These DEGs were primarily enriched in the pathways such as phenylpropanoid biosynthesis, starch and sucrose metabolism, and plant-pathogen interaction etc. 

CONCLUSION: There were differences in the contents of psoralen and bergapten among the three leaf shapes of F. hirta. The phenylpropanoid biosynthesis and plant-pathogen interaction pathway may play crucial roles in the biosynthesis and accumulation of psoralen and bergapten in F. hirta. This study preliminarily revealed the correlation between the leaf morphology and major active compounds of F. hirta, and extended its public transcriptome database, which will provide reference for further utilizing different leaf shape of F. hirta germplasm resources and quality breeding.