Jasmonate signalling in the regulation of rubber biosynthesis in laticifer cells of rubber tree, Hevea brasiliensis

Abstract

Rubber trees are the world's major source of natural rubber. Rubber-containing latex is obtained from the laticifer cells of the rubber tree (Hevea brasiliensis) via regular tapping. Rubber biosynthesis is a typical isoprenoid metabolic process in the laticifer cells; however, little is known about the positive feedback regulation caused by the loss of latex that occurs through tapping. In this study, we demonstrate the crucial role of jasmonate signalling in this feedback regulation. The endogenous levels of jasmonate, the expression levels of rubber biosynthesis-related genes, and the efficiency of in vitro rubber biosynthesis were found to be significantly higher in laticifer cells of regularly tapped trees than those of virgin (i.e. untapped) trees. Application of methyl jasmonate had similar effects to latex harvesting in up-regulating the rubber biosynthesis-related genes and enhancing rubber biosynthesis. The specific jasmonate signalling module in laticifer cells was identified as COI1-JAZ3-MYC2. Its activation was associated with enhanced rubber biosynthesis via up-regulation of the expression of a farnesyl pyrophosphate synthase gene and a small rubber particle protein gene. The increase in the corresponding proteins, especially that of farnesyl pyrophosphate synthase, probably contributes to the increased efficiency of rubber biosynthesis. To our knowledge, this is the first study to reveal a jasmonate signalling pathway in the regulation of rubber biosynthesis in laticifer cells. The identification of the specific jasmonate signalling module in the laticifer cells of the rubber tree may provide a basis for genetic improvement of rubber yield potential.

Recent Advances in Plant Chemical Biology of Jasmonates

“…However, the tools developed to date are limited to the upregulation of plant defense responses against necrotrophic pathogen or insect attack, and although these are important, more versatile tools such as those that are able to improve the efficiency of plant growth are highly desirable. One research priority is a tool that is able to upregulate [79] secondary metabolite production in medicinal plants without concomitant growth inhibition [81,82], and recent studies have revealed the relationship between jasmonate signaling and transcription factors (TFs), which govern the biosynthetic genes of secondary metabolites [83,84]. Thus, chemical control of individual TF or JAZs in the upstream pathway could be an efficient strategy.…”

Genome-wide identification and expression analysis of the phosphatase 2A family in rubber tree (Hevea brasiliensis)

“…The enhanced in vitro rubber biosynthesis of latex from tapped trees is closely associated with the up-regulation of the genes encoding the key enzymes for rubber biosynthesis by activating jasmonate signalling [14]. It may also be related to the changes in the key enzyme activity by phosphorylation modification.…”

“…In natural rubber production, the milky latex is obtained by successive tapping, a process of artificially severing the laticifer rings every 2-3 days [13]. Latex exploitation by tapping enhances latex regeneration and the efficiency of natural rubber biosynthesis by activating jasmonate signalling in laticifers [14]. To increase the tapping efficiency, ethrel is applied to increase the rubber yield per tapping to economize on tapping workers.…”

“…Prolongation of the duration of latex flow mainly increases the rubber yield per tapping by increasing the level of a 44 kDa protein in the cytosol of laticifer cells [15]. Ethrel itself, however, inhibits rubber biosynthesis [14].…”

Tobacco rattle virus -induced gene silencing in Hevea brasiliensis

“…is an important rubber-producing plant of Euphorbiaceae [1,2]. The valuable of rubber tree as a sole commercial source rubber-producing plant led to enormous interest in understanding the natural rubber biosynthesis and regulation [3][4][5]. Natural rubber (NR) is regarded as a valuable industry raw material which is synthesized in latex of laticifers [6,7].…”