Résumé
The rubber tree is the only source of natural rubber exploited on an industrial scale. Natural rubber has been placed on the list of strategic materials for Europe since 2017. The cis-1,4 polyisoprene is biosynthesized from sucrose produced by photosynthesis in the leaves and translocated to specialized cells called laticifers. After loading, sucrose is metabolized into isopentenyl pyrophosphate (IPP), a monomer used for elongation of the polymer biosynthesized in the rubber particles of latex cells. All genes involved in the NR biosynthesis pathway have been identified in the genomic sequences of the Chinese rubber clone Reyan 7-33-97 [1] and in clone PB 260 [2], and particularly the genes encoding the Rubber Elongation Factor (REF1–8) and Small Rubber Particle Protein (SRPP1–10) families. Difficulties persist in establishing a functional model for the final step of polyisoprene chain polymerization. Routine somatic embryogenesis procedure [3-5] has allowed developing an efficient Agrobacterium tumefaciens-mediated genetic modification [6-8]. Several functional studies by endogenous or exogenous gene overexpression have been successfully carried out allowing the discovery of new functions in Hevea, notably in laticifier cell differentiation [9-11]. The identification of a highly expressed HbMIR408 gene allowed the development of a gene silencing strategy using artificial miRNA leading to a partial inactivation of the uidA transcript, present in a transgenic line overexpressing this gene [12]. The same approach is underway with the use of sgRNAs targeted against the uidA gene in order to obtain total inactivation. The partial or total extinction of the expression of the genes coding for the proteins of the biosynthetic complex could make it possible to disentangle the role of each protein that constitutes it by taking into account the functional redundancy.