Abstract：Loquat (Eriobotrya japonica) is an important plant species resources of traditional Chinese medicine. It has been reported that the main activity components in E. japonica were pentacyclic triterpenoids, which have been extensively known for its important and wide biological activity. Comparing with original plant plants, the content of tpentacyclic triterpenoids in E. japonica obtained by suspension culture is much higher. In this study, the genetic basis of these active components enrichment after suspension culture was analyzed to improve the synthesis mechanism of tricyclic triterpenoids in plant and provide reference for the artificial regulation of terpenoids in large-scale loquat cell suspension culture. The loquat leaves (sampleⅠ), the loquat callus on solid media (the necessary stage of suspension culture, sampleⅡ), the loquat suspension cell lines (two regulations rich in pentacyclic triterpenoids, sample Ⅲ and sample Ⅳ) were sequenced by Illumina Hiseq4000. The results are as follows: De novo assembly , protein function annotations, Gene Ontology (GO) annotations and Metabolic pathway analysis (the Kyoto Encyclopedia of Genes and Genomes) of Unigenes were obtained using bioinformatics. A total of 123 685 Unigenes were obtained with an average length of 804.44 bp. The genes related to triterpene synthesis expression profiles of samples Ⅰ and three other cultured cells (samples Ⅱ, Ⅲ, Ⅳ) were significantly different, but the difference was not significant among the three cultured cells. From expression profile of the differentially expressed genes in the skeleton formation and modification metabolic pathways of triterpenoid, 10 potential-selection genes were selected by the intersection of the different expressed genes between the samples and the importance of the genes reported. Those genes are two acetyl-CoA acetyltransferase genes (AACTs), squalene synthase gene (SQS), two squalene monooxygenase-like genes (SQEs), two amyrin synthase genes (ASs), cytochrome P450 gene (CYP450) and two UDP-glycosyltransferase–like genes (UGTs). And more from the overall analysis of those genes indicated that the expression level of those genes and the content of the target products had some relevance. Those genes will contribute significantly to further research and analysis for the pathway of triterpenes in this species. At the same time, the synthesis route of the pentacyclic triterpenoid in the loquat callus stage (sampleⅡ)had been opened extensively, which is an important intermediate stage of the suspension culture of the loquat cells. This study will help to improve the synthesis mechanism and the applied research of plant pentacyclic triterpenoids.
