# Ethylene-Enhanced Latex Proteome Is Involved in Stimulation of Natural Rubber Production in the Hevea Rubber Tree

## TL;DR

This study shows how ethylene boosts natural rubber production in the Hevea tree by regulating key proteins, especially HbCPT7, which was shown to increase rubber content when overexpressed.

## Contribution

Identifies HbCPT7 as a key ethylene-responsive protein in natural rubber biosynthesis and validates its role through overexpression in a model plant.

## Key findings

- Ethylene primarily regulates rubber production at the translational/post-translational level.
- Overexpression of HbCPT7 in Taraxacum kok-saghyz increased rubber content by 27.3% and molecular weight by 1.8-fold.
- 64 genes and 35 proteins are directly involved in natural rubber biosynthesis, with CPT7 showing significant accumulation after ethylene application.

## Abstract

The Hevea brasiliensis is the only commercial source of natural rubber. In natural rubber production, exogenous ethylene is widely used as a stimulant for increasing rubber latex yield. To reveal the potential regulation mechanisms for ethylene stimulation of natural rubber production in H. brasiliensis, we performed an integrative analysis of transcriptomics and proteomics for ethylene-stimulated rubber latex. A total of 35,306 genes and 3620 proteins were successfully identified from the different latex samples upon ethylene stimulation. Gene Ontology analysis revealed that these genes are mainly involved in cytoplasm and cytoplasmic and catalytic activity. Kyoto Encyclopedia of Genes and Genomes analysis demonstrated that their pathways are mainly enriched in alanine and glutamate metabolism, carbon metabolism, and carbon fixation. Ethylene stimulation played a key regulatory role at the translational/post-translational modification level to promote natural rubber synthesis. Notably, 64 genes and 35 proteins are directly involved in natural rubber biosynthesis. Among them, several family members of 3-hydroxy-3-methylglutaryl coenzyme A reductase, small rubber particle protein, and cis-prenyl transferase (CPT) are ethylene-responsive ones. It is noteworthy that accumulation of CPT7 was significantly increased after ethylene application. Overexpression of HbCPT7 in a rubber-producing model plant, Taraxacum Kok-saghyz, resulted in a significant increase in rubber content in the transgenic Taraxacum Kok-saghyz roots.

•The gene and protein profiles of ethylene-stimulated rubber latex were provided.•A total of 35,306 genes and 3620 proteins are identified from rubber latex.•Ethylene-stimulated rubber yield increase primarily involves translational-level regulation.•Cis-prenyl transferase 7 is the key component for natural rubber production.

The gene and protein profiles of ethylene-stimulated rubber latex were provided.

A total of 35,306 genes and 3620 proteins are identified from rubber latex.

Ethylene-stimulated rubber yield increase primarily involves translational-level regulation.

Cis-prenyl transferase 7 is the key component for natural rubber production.

Integrative transcriptomic and proteomic analyses of ethylene-stimulated rubber latex in Hevea brasiliensis revealed that ethylene-stimulated rubber yield increase primarily involves translational-level regulation. H. brasiliensis cis-prenyl transferase (HbCPT7) as a key regulator of natural rubber biosynthesis. Functional validation via HbCPT7 overexpression in Taraxacum kok-saghyz increased rubber content by 27.3% and molecular weight by 1.8-fold, highlighting its pivotal role in natural rubber biosynthesis. This study provides a multiomics framework for understanding ethylene-induced rubber production and identifies HbCPT7 as a potential target for genetic improvement in rubber crops.