Mycoparasitic Scytalidium parasiticum as a potential biocontrol agent against Ganoderma boninense basal stem rot in oil palm^*

* All the experiments undertaken in this study comply with the current laws of the country where they were performed.

ABSTRACT

The objective of this study was to assess the interactions between Scytalidium parasiticum (Sp) and Ganoderma boninense, the causal agent of basal stem rot (BSR) in oil palm (Elaeis guineensis). When compared with Scytalidium ganodermophthorum and Scytalidium sphaerosporum, Sp showed greater inhibition towards all Ganoderma isolates during dual-culture assays. At the interaction zone, coiling of host hyphae, formation of short lateral enlarged contact structures, and production of appressorium-like organs organs were observed in Sp on G. boninense. These were followed by the degradation, shrinkage, and deformation of G. boninense mycelia. Sp reduced mycelial survival and fruiting body regeneration of G. boninense. Sp's non-volatile metabolites suppressed the growth of G. boninense. Our results show that Sp could be a necrotrophic mycoparasite of G. boninense. Nursery experiments revealed that Sp was non-pathogenic to oil palm seedlings, and it could suppress Ganoderma infection and reduce disease severity. Sp increased the height of palms in the positive control with non-Ganoderma-inoculated rubber wood block and Sp inoculum compared to similar control without Sp. Leaf area was greater in the G. boninense G8 inoculated palms when Sp was present compared to without Sp. These results show that Sp might be a potential biocontrol candidate against BSR.

KEYWORDS:

• Elaeis guineensis
• fungal metabolite
• necrotrophic parasitism
• pathogenicity
• Xylogone

Acknowledgements

The authors would like to thank the staff and interns at AAR Crop Protection Laboratory for their valuable technical assistance: I. Hassim, M. A. Hassan Basri, M. S. Mohd. Shaharudin, N. Anuar, S. Y. Wong, and S. J. Chua. The first author would like to thank S. Y. Chin for providing assistance in sourcing the rubber wood blocks, and L. W. Cheah for English proofreading and editing. Furthermore, GYK and MNF would like to thank Dr Roland Kirschner from the National Central University, Taiwan, for great discussions on the topic of fungicolous fungi from the Ganoderma species. The authors would also like to thank their principals, Boustead Plantation Berhad and Kuala Lumpur Kepong Berhad for the financial backing of the present research, and the permission given to them for the publication of their findings.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCiD

Yit Kheng Goh http://orcid.org/0000-0003-2884-7273

Teik Khiang Goh http://orcid.org/0000-0002-6322-0196

Notes

* All the experiments undertaken in this study comply with the current laws of the country where they were performed.