EXPRESSION RESPONSES OF PATHOGENESIS-RELATED PROTEINS IN TOLERANT AND SUSCEPTIBLE Hevea brasiliensis CLONES TO THE WHITE ROOT DISEASE

Abstract

Pathogenesis-related proteins play crucial functions in the plant defense with antimicrobial activity response to pathogen infections. In this study, cDNA parts of selected antifungal genes (HbPR-2, HbPR-4 and HbPR-5) were isolated from Hevea brasiliensis, the parts spanning 1,120, 233, and 517 bp, respectively. In BLASTP analysis HbPR2 showed a Glyco_hydro_17 domain; HbPR-4 showed a Barwin domain; and HbPR-5 contained a GHG-TLP-SF domain. The sequence alignment of amino acids indicated high similarities to the PR-2, PR-4 and PR-5 genes found in other plants. Transcriptional profiles from quantitative real time-PCR were compared in three Hevea clones, namely PB5/51 (a tolerant clone), BPM24 and RRIM600 (susceptible clones), after inoculation with Rigidoporus microporus at 0, 12, 24, 48, 72 and 96 h. The results revealed that these gene transcripts were more active in the tolerant clone than in the susceptible clones. These clearly indicate varied defense responses across clonal varieties, in the important context of host-pathogen interactions between the white root disease and rubber trees. This gives the priming strategy for tolerant rubber selection.