Antagonistic Activity Assessment of Fungal Endophytes from Oil Palm Tissues Against Ganoderma boninense Pat

Abstract

Ganoderma boninense is a major pathogen in oil palm plantations which easily infects basal stems and thus it is difficult to be eradicated. Fungal endophytes from healthy oil palm tissues can be used as biological control agents in host plants against G. boninense. For selecting the antagonist candidates against G. boninense, a simple method of dual culture assay was used. A total of 526 endophytic fungi were isolated from 531 oil palm segments in three of plantations location in Medan, North Sumatera province of Indonesia i.e. Kuala Bekala (KB), Medan Tuntungan (MT) and Medan Johor (MJ). Overall, fungal isolation rate in oil palm segments was 0.99 and colonization rate was 77.2% and the highest being found in the KB plantation. From different sample parts, we found that palm leaf midrib had the highest value of colonization and isolation rate. Based on six categories in qualitative dual culture assay, 53 isolates showed a high antagonism effect to G. boninense, twenty two of which were found to have a Colony Growth Inhibition (% CGI) value of more than 80%. Further studies showed that all 22 isolates exhibited a chitinolytic activity on Coloidal Chitin Bromcresol purple (CCBp) assay while only ten (crude extract of liquid culture) inhibited mycelial colony of G. boninense. From microscopic observation, fungal endophytes attached themselves to the hyphae of G. boninense at the interaction zone and causing hypae abnormalities to the pathogen. Almost all selected fungal endophytes potential to be biocontrol agents against G. boninense belong to the Genera of Trichoderma.