Latex-specific transcriptome analysis reveals mechanisms for latex metabolism and natural rubber biosynthesis in laticifers of Hevea brasiliensis

Natural rubber, produced in the laticifers of the para rubber tree (Hevea brasiliensis), is a valuable biopolymer of commercial and strategic importance. While the basic pathway of rubber biosynthesis has been established, further understanding of its regulatory mechanisms might be obtained by studying laticifer-specific gene expression. Here, gene expression patterns was investigated in five different tissues of the rubber tree to explore differentially expressed genes (DEGs). The expression of 4122 high expression genes and 6485 low expression genes in the laticifer was enriched in various metabolic pathways related to rubber biosynthesis. The study results suggest that isopentenyl pyrophosphate (IPP), a principal precursor of natural rubber, is supplied mainly via the mevalonate (MVA) pathway in rubber biosynthesis, rather than the 2-C-methyl-D-erythritol-4-phosphate (MEP) pathway. The ubiquitin-proteasome system (UBS) that is surprisingly active in the laticifer might serve as an important metabolic control mechanism in rubber biosynthesis. The involvement of latex specific transcription factors (TFs) was identified in seven plant hormone signal transductions, suggesting that jasmonate (JA) signaling is active in the positive regulation of rubber biosynthesis.