Project description:Pseudostellaria heterophylla is a traditional Chinese herbal medicine, which has been cultivated for hundreds of years. Viral diseases of P. heterophylla occur widely and limit the yield and quality of this medicinal plant. In this study, five leaf samples of P. heterophylla with typical viral symptoms were collected from four main producing regions that are distributed in Fujian, Guizhou, and Anhui Provinces in China and analyzed by next-generation sequencing. Comprehensive bioinformatics analyses revealed that nine viruses in five genera Carlavirus, Potyvirus, Fabavirus, Cucumovirus, and Amalgavirus infected P. heterophylla. Among these viruses, three novel and two known carlaviruses, tentatively designated Pseudostellaria heterophylla carlavirus 1, 2, and 3 (PhCV1, PhCV2, and PhCV3), Jasmine virus C isolate Ph (Ph-JVC) and Stevia carlavirus 1 isolate Ph (Ph-StCV1), respectively, were first identified in P. heterophylla. PhCV1-3 share a similar genomic organization and clear sequence homology with members in the genus Carlavirus and could potentially be classified as new species of this genus. One novel amalgavirus, tentatively designated P. heterophylla amalgavirus 1 (PhAV1), was first identified in P. heterophylla. It had a typical genomic organization of the genus Amalgavirus. In PhAV1, the + 1 programmed ribosomal frameshifting, which is prevalent in most amalgaviruses, was identified and used in the expression of RNA-dependent RNA polymerase (RdRp). Combined with a phylogenetic analysis, PhAV1 could potentially be classified as new species of the genus Amalgavirus. In addition, multiple Broad bean wilt virus 2 (BBWV2) variants, Turnip mosaic virus (TuMV), and Cucumber mosaic virus (CMV), which have been reported in P. heterophylla, were also detected in this study. The distribution of PhCV1-3, Ph-JVC, Ph-StCV1, TuMV, BBWV2, and CMV in four production regions in Fujian, Guizhou, and Anhui Provinces was determined. This study increased our understanding of P. heterophylla virome and provided valuable information for the development of a molecular diagnostic technique and control of viral diseases in P. heterophylla.
Project description:Pseudostellaria heterophylla (Miq.) Pax is a mild tonic herb widely cultivated in the Southern part of China. The tuberous roots of P. heterophylla accumulate high levels of secondary metabolism products of medicinal value such as saponins, flavonoids, and isoquinoline alkaloids. Despite numerous studies on the pharmacological importance and purification of these compounds in P. heterophylla, their biosynthesis is not well understood. In the present study, we used Illumina HiSeq 4000 sequencing platform to sequence the RNA from flowers, leaves, stem, root cortex and xylem tissues of P. heterophylla. We obtained 616,413,316 clean reads that we assembled into 127, 334 unique sequences with an N50 length of 951 bp. Among these unigenes, 53,184 unigenes (41.76%) were annotated in a public database and 39, 795 unigenes were assigned to 356 KEGG pathways; 23,714 unigenes (8.82%) had high homology with the genes from Beta vulgaris. We discovered 32, 095 DEGs in different tissues and performed GO and KEGG enrichment analysis. The most enriched KEGG pathway of secondary metabolism showed up-regulated expression in tuberous roots as compared with the ground parts of P. heterophylla. Moreover, we identified 72 candidate genes involved in triterpenoids saponins biosynthesis in P. heterophylla. The expression profiles of 11 candidate unigenes were analyzed by quantitative real-time PCR (RT-qPCR). Our study established a global transcriptome database of P. heterophylla for gene identification and regulation. We also identified the candidate unigenes involved in triterpenoids saponins biosynthesis. Our results provide an invaluable resource for the secondary metabolites and physiological processes in different tissues of P. heterophylla.