RNA-seq derived identification of coronatine-regulated genes putatively involved in terpenoid biosynthetic pathway in the rubber tree Hevea brasiliensis

Abstract

Rubber tree (Hevea brasiliensis) is a woody plant of the Spurge family (Euphorbiaceae) and the most economically important member of the genus Hevea. Rubber trees are often damaged and exposed to the attack of pathogens through wounds during and after tapping periods. Jasmonic acid (JA) and methyl jasmonate (MeJA), collectively termed jasmonates (JAs), are signaling molecules that are produced by plants, especially when subjected to environmental stresses. JA/MeJA treatment triggers the biosynthesis of many specialized metabolites including terpenoids through transcriptional reprogramming. To gain molecular insights into terpenoid metabolism and mechanism underlying rubber tree's responses to stress signals such as wounding and pathogenicity, we performed an RNA-seq analysis of H. brasiliensis treated with either water or coronatine (COR) - a structural and functional mimic of JAs. We reconstructed the transcriptomes from the published RNA-sequencing data under the guidance of the newly released high-quality chromosome-level genome assembly of H. brasiliensis cultivar GT1 and screened for genes that are differently expressed between the two treatments. The putative functions and pathways of the differently expressed genes (DEGs) were obtained by using BLASTX search against NCBI non-redundant database, followed by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) mapping. As a result, six out of the 446 identified DEGs were mapped to terpenoid metabolism pathway, five of which were up-regulated by coronatine treatment. This result provides a clue to gain insight into the genetic basis underlying terpenoid-related yield and resistance traits in the rubber tree.