Basal stem rot (BSR) of oil palm is a disastrous disease caused by a white-rot fungus Ganoderma boninense Pat. Non-ribosomal peptides (NRPs) synthesized by non-ribosomal peptide synthetases (NRPSs) are a group of secondary metabolites that act as fungal virulent factors during pathogenesis in the host. In this study, we aimed to isolate NRPS gene ofG. boninense strain UPMGB001 and investigate the role of this gene during G. boninense-oil palm interaction. The isolated NRPS DNA fragment of 8322 bp was used to predict the putative peptide sequence of different domains and showed similarity with G. sinense (85%) at conserved motifs of three main NRPS domains. Phylogenetic analysis of NRPS peptide sequences demonstrated that NRPS of G. boninensebelongs to the type VI siderophore family.
Fig: Conserved domains on predicted protein sequence using NCBI Conserved Domain Search. Protein classification: AMP-binding and AA-adenyl-domain belong to adenylation domain, A_NRPS_SidN3_Like is the adenylation A domain of siderophore-synthesizing NRPS, EntF is a NRPS synthetase component F that is responsible for secondary metabolites biosynthesis, catabolism and transport. PP_binding (phosphopantetheine attachment site) is a 4′-phosphopantetheine prosthetic group is linked by a serine. The role of this prosthetic group as a ‘swinging arm’ for the connection of activated fatty acid and amino-acid groups to Condensation domain. Condensation catalyzes a condensation process to form peptide bonds in NRP biosynthesis. AFD_Class_I superfamily, Condensation superfamily, pp-binding superfamily.
The roots of 6-month-old oil palm seedlings were artificially inoculated for studying NRPS gene expression and disease severity in the greenhouse. The correlation between high disease severity (50%) and high expression (67-fold) of G. boninense NRPS gene at 4 months after inoculation and above indicated that this gene played a significant role in the advancement of BSR disease. Overall, these findings increase our knowledge on the gene structure of NRPS in G. boninense and its involvement in BSR pathogenesis as an effector gene.
Shokrollahi, N., Ho, CL., Zainudin, N.A.I.M. et al. Identification of non-ribosomal peptide synthetase in Ganoderma boninense Pat. that was expressed during the interaction with oil palm. Sci Rep 11, 16330 (2021). https://doi.org/10.1038/s41598-021-95549-8