Natural rubber (cis-1,4-polyisoprene, NR) is an important raw material utilized widely in the manufacturing of medical, agricultural, and industrial products. Rubber tree (Hevea brasiliensis) and several alternative rubber-producing plants (Taraxacum kok-saghyz, Lactuca sativa, and Parthenium argentatum) have the capability to produce high-quality NR. With the progress of genome sequencing, similar rubber biosynthesis pathways have been discovered among different rubber-producing plant species. NR is synthesized and stored in rubber particles, which are specialized organelles comprising a hydrophobic NR core surrounded by a lipid monolayer and membrane-bound proteins. The rubber transferase complex is considered to be the pivotal enzyme involved in catalyzing NR biosynthesis. However, the exact compositions of the RT complex in rubber-producing plants remain elusive and poorly understood. Here, we review the progress of genome sequencing, natural rubber biosynthesis, and the components of the RT complex in rubber-producing plants. We emphasize that identifying the detailed components of the RT complex holds great significance for exploring the mechanism of NR biosynthesis and accelerating molecular breeding in rubber-producing plants.

Transgenic technology is a crucial tool for gene functional analysis and targeted genetic modification in the para rubber tree (Hevea brasiliensis). However, low efficiency of plant regeneration via somatic embryogenesis remains a bottleneck of successful genetic transformation in H. brasiliensis. Enhancing expression of GROWTH-REGULATING FACTOR 4 (GRF4)-GRF-INTERACTING FACTOR 1 (GIF1) has been reported to significantly improve shoot and embryo regeneration in multiple crops. Here, we identified endogenous HbGRF4 and HbGIF1 from the rubber clone Reyan7-33-97, the expressions of which dramatically increased along with somatic embryo (SE) production. Intriguingly, overexpression of HbGRF4 or HbGRF4-HbGIF1 markedly enhanced the efficiency of embryogenesis in two H. brasiliensis callus lines with contrasting rates of SE production. Transcriptional profiling revealed that the genes involved in jasmonic acid response were up-regulated, whereas those in ethylene biosynthesis and response as well as the S-adenosylmethionine-dependent methyltransferase activity were down-regulated in HbGRF4- and HbGRF4-HbGIF1-overexpressing H. brasiliensis embryos. These findings open up a new avenue for improving SE production in rubber tree, and help to unravel the underlying mechanisms of HbGRF4-enhanced somatic embryogenesis.

Natural rubber (NR), derived from the latex of the Para rubber tree (Hevea brasiliensis), is an irreplaceable raw material for the tire, medical, and engineering industries. Despite its global economic importance, rubber tree breeding has historically been constrained by a narrow genetic base originating from the 1876 Wickham collection and a prolonged juvenile phase. This review synthesizes historical germplasm conservation efforts—most notably the IRRDB 1981 Amazonian expedition—and over a century of clonal selection that has increased NR yields nearly tenfold. We critically assess recent biotechnological advances, including somatic embryogenesis and Agrobacterium-mediated transformation, highlighting their current bottlenecks and the potential of developmental regulators to overcome recalcitrance. A major focus is the rapid acceleration of genomic resources, tracing the progression from early draft assemblies to recent telomere-to-telomere (T2T) haplotype-resolved genomes and pan-genome analyses. We further summarize quantitative trait loci (QTL) mapping and genome-wide association studies (GWAS) that have identified key genes governing growth traits, latex yield, and laticifer differentiation. Finally, we outline future perspectives emphasizing the integration of CRISPR/Cas9-based gene editing with multi-omics-driven genomic selection to drastically shorten breeding cycles. By consolidating these interdisciplinary advancements, this review underscores the transition of rubber tree improvement from traditional selection toward precision molecular breeding, thereby ensuring the sustainable supply of this strategic industrial resource.