Molecular cloning and characterization of putative virulence factors of Ganoderma boninense
M. S. JEE1,2, C. L. HO2, M. T. YUSOF2, S. Y. L. LAU1, L. MELLING1

Ganoderma boninense is a white rot fungus which causes basal stem rot (BSR) disease in oil palm. This study aims to isolate the transcripts for putative virulence factors from G. boninense and to profile their gene expressions during plant-pathogen interactions. Four putative virulence factors that were present in the G. boninense-treated oil palm root transcriptomes from a previous study were selected. The full-length cDNAs of the candidate transcripts for putative metalloproteinase (U14090), aspartic protease (U42611), polysaccharide deacetylase (U128397), and lipase (U56931) were isolated from G. boninense BLSM5B, cloned, and verified by sequencing. Gene expression analysis of these four genes in treatments with salicylic acid (SA), jasmonic acid (JA), and hydrogen peroxide (H2O2) that mediate plant defense signaling and respiratory burst oxidation showed that only SA downregulated U56931. On the other hand, oil palm roots in direct contact with G. boninense mycelia upregulated U14090 consistently at 24- and 48-hours post inoculation (hpi) as compared to the uninoculated control. The findings provided an insight on the expression of putative virulence factors encoding hydrolytic enzymes from G. boninense during plant-pathogen interactions. This information could serve as a clue for gene-targeted study in development of effective cure against G. boninense to minimize yield loss of the oil palm industry.

1-Sarawak Tropical Peat Research Institute, 94300 Kota Samarahan, Sarawak, MALAYSIA.

2-Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor, MALAYSIA.