Genetic polymorphism and expression of the rubber elongation factor gene (<em>ref</em>) in <em>Hevea brasiliensis</em> cultivars

Abstract

Rubber Elongation Factor (REF) protein is one of the most abundant proteins found in Hevea latex. Investigation on the organization and expression of the gene encoding REF protein in commercially planted Hevea brasiliensis cultivars is important to shed light on its possible role in rubber biosynthesis, the studies of Hevea latex allergy and in molecular breeding of new rubber clones. RFLP analysis of the Hevea brasiliensis cultivars used in this study, showed the occurrence of the polymorphic forms of the ref gene and its possibility to be used as an important genetic marker in Hevea breeding and selection. The RRIC 100 series clones produced more bands indicating the possibility of occurrence of more ref gene copies. The RFLP analysis of the progeny derived by crossing RRIC 110 and IAN 45/710 proved the nuclear inheritance pattern of the ref gene with two alleles at ref loci E-1 and E-3. The gene expression studies showed the differential expression of the ref gene between leaf and laticiferous tissues with high abundance of ref gene transcripts in lattices of Hevea brasiliensis. The ref gene expression was approximately 100 fold higher in latex than in leaves. The intensities of the hybridisation signals obtained from latex RNA of different clones showed variation implying the existence of the genotypic differences for ref gene expression.