In situ 13CO2 labelling of rubber trees reveals a seasonal shift in the contribution of the carbon sources involved in latex regeneration

Abstract

Rubber trees (Hevea brasiliensis) are the main source of natural rubber, extracted from latex, which exudes from the trunk after tapping. Tapped trees require large amounts of carbon (C) to regenerate the latex after its collection. Knowing the contribution of C sources involved in latex biosynthesis will help in understanding how rubber trees face this additional C demand. Whole crown 13CO2 pulse labelling was performed on 4-year-old rubber trees in June, when latex production was low, and in October, when it was high. 13C content was quantified in the foliage, phloem sap, wood, and latex. In both labelling periods, 13C was recovered in latex just after labelling, indicating that part of the carbohydrate was directly allocated to latex. However, significant amounts of 13C were still recovered in latex after 100 d and the peak was reached significantly later than in phloem sap, demonstrating the contribution of a reserve pool as a source of latex C. The contribution of new photosynthates to latex regeneration was faster and higher when latex metabolism was well established, in October, than in June. An improved understanding of C dynamics and the source–sink relationship in rubber tree is crucial to adapt tapping system practices and ensure sustainable latex production.

Transcript and Protein Profiling Provides Insights Into the Molecular Mechanisms of Harvesting-Induced Latex Production in Rubber Tree

“…In regularly tapped Hevea trees, the main metabolic activity of the laticifers is latex regeneration, which centers on the biosynthesis of NR that consists of about 90% of the latex dry weight ( d’Auzac et al, 1997 ). Sucrose is the precursor material for rubber biosynthesis in laticifers, and provides the carbon skeleton and energy required for latex regeneration ( Tupý, 1989 ; Duangngam et al, 2020 ). In Hevea trees that are tapped at two-four days of intervals, a tree produces dozens to hundreds of milliliters of fresh latex, and the removed latex could be effectively recovered before the next tapping ( d’Auzac et al, 1997 ; Tang et al, 2010 ).…”

Foliar and flowering phenology of three rubber (Hevea brasiliensis) clones in the eastern plains of Colombia

“…Subsequently, the refoliation begins before the beginning of the rains. Duangngam et al (2020) mentioned that defoliation and refoliation occur from January to March in Thailand (13.5°N), coinciding with the dry season (December to April). Various authors have mentioned the relationship of vegetative and reproductive flows with the transition from dry to rainy seasons in various crops, such as Orduz and Garzón (2012) in "Valencia" orange and Borchert (1983) in some forest species.…”

Transcript Profiling Provides Insights into the Molecular Mechanisms of Harvesting-activated Latex Regeneration in Virgin Rubber Trees

“…In regularly tapped Hevea trees, the main metabolic activity of the laticifers is latex regeneration, which centers on the biosynthesis of rubber hydrocarbon that accounts for about 90% of the dry weight of fresh latex [3]. Sucrose has been identi ed as the precursor material for rubber biosynthesis in laticifers, providing the carbon skeleton and energy required for latex regeneration [11,36]. In Hevea trees normally tapped at intervals of 2-4 days, each tree produces dozens to hundreds of milliliters of fresh latex, and the removed latex could be effectively recovered before the next tapping to ensure the sustained productivity of the tree [3,12].…”