The endophytic bacteria of oil palm and areca nut are beneficial as antagonist of Ganoderma boninense and potential as plant growth promoter

Abstract

Ganoderma boninense is the pathogenic fungi causing Basal Stem Rot (BSR) disease on oil palm. This study aimed to obtain potential endophytic bacteria as antagonist as well as plant growth promoting rhizobacteria (PGPR) agents. This study employed three stepwises as follows: 1) isolation and selection of endophytic bacteria in vitro, 2) in vitro antagonism and plant growth promoting assays, and 3) molecular identification of the bacteria. Endophytic bacteria isolated from the root tissues of oil palm and areca nut totally produced 88 isolates. Among those, EG17, EG26, EG113, EG215, AC28, AC112, and AC214 were investigated further because they showed negative result on both hypersensitive and hemolytic assays suggesting that these are not plant pathogen and harmless to mammals. Antagonism assay showed that three isolates with highest growth inhibitions to G. boninense were exhibited by EG26, EG113 and AC112 with 56.80%, 56.51% and 56.11%, respectively. These isolates also significantly enhanced the growth of rice seedlings as a model plant, particularly AC112 that increased root length and plant height up to 30.77% and 39.57%. Molecular identification using 16S rDNA sequencing showed that EG26, EG113 and AC112 were identical to Bacillus subtilis strain VD1, Bacillus velezensis strain Bac57, Bacillus toyonensis strain JCT-23, respectively.