Full-length transcriptome analysis of multiple organs and identification of adaptive genes and pathways in Mikania micrantha.

Mikania micrantha is a notorious invasive weed that has caused huge economic loss and negative ecological consequences in invaded areas. This species can adapt well to invasive environments with various stress factors. The identification of gene families and functional pathways related to environmental adaptability is lack in M. micrantha at the multi-organ full-length transcriptome level. In this study, we sequenced the transcriptomes of five M. micrantha organs using PacBio single-molecule real-time sequencing and Illumina RNA sequencing technologies. Based on the transcriptome data, full-length transcripts were captured and gene expression patterns among the five organs were analyzed. KEGG enrichment analysis of genes with higher expression indicated their special roles in environmental stress response and adversity adaptation in the various five organs. The gene families and pathways related to biotic and abiotic factors, including terpene synthases, glutathione S-transferases, antioxidant defense system, and terpenoid biosynthesis pathway, were characterized. The expression levels of most differentially expressed genes in the antioxidant defense system and terpenoid biosynthesis pathway were higher in root, stem, and leaf than in the other two organs, suggesting that root, stem, and leaf have strong ability to respond to adverse stresses and form the important organs of terpenoid synthesis and accumulation. Additionally, a large number of transcription factors and alternative splicing events were predicted. This study provides a comprehensive transcriptome resource for M. micrantha, and our findings facilitate further research on the adaptive evolution and functional genomics of this species.