BIODIVERSITAS ISSN: 1412-033X Volume 21, Number 1, January 2020 E-ISSN: 2085-4722 Pages: 28-33 DOI: 10.13057/biodiv/d210105 Induced resistance by Bacillus subtilis on oil palm seedling infected by Ganoderma boninense FIFI PUSPITA 1, , HADIWIYONO 2 , SUSILO HAMBEG POROMORTO 2 , DEWI INDRIYANI ROSLIM 1 1 Department of Agrotechnology, Faculty of Agriculture, Universitas Riau. Jl. H.R. Soebrantas Km. 12,5, Kampus Bina Widya, Simpang Baru, Pekanbaru 28293, Riau, Indonesia. Tel.: +62-761-63270, Fax.: +62-761-63271,  email: fipspt@gmail.com 2 Progam of Agricultural Sciences, Graduate School, Universitas Sebelas Maret. Jl. Ir. Sutami 36A,. Surakarta 57 126, Central Java, Indonesia Manuscript received: 6 August 2019. Revision accepted: 2 December 2019. Abstract. Puspita F, Hadiwiyono, Poromorto S. H, Roslim D. I. 2020. Induced resistance by Bacillus subtilis on Ganoderma boninense infected oil palm seedling. Biodiversitas 21: 28-33. Basal Stem Rot (BSR) caused by Ganoderma boninense Pat is the most important disease in oil palm plantations. The use of biological resistance inducer is a promising alternative disease-control. The research evaluated the potential and mechanism of endophytic Bacillus subtilis as resistance inducer agent of oil palm seedlings to infection of G. boninense. The Experiment was carried out using a completely randomized design consisting of 4 treatments and 3 replications namely of endophytic B. subtilis with four inoculum densities (0, 10 11 , 10 12 , and 10 13 cfu.mL -1 ) on oil palm before inoculation of G. boninense. The observation variables were incubation period, disease intensity, growth and concentration of salicylic acid in leaf extract of oil palm seedlings. In addition, the ability of B. subtilis to produce IAA in liquid Pikovskaya medium enriched by tryptophan was assayed. The results showed that B. subtilis was potential as biological resistance inducer agents of oil palm seedlings to infection of G. boninense. The induced resistance was related to increasing growth, salicylic acid in leaf the seedlings and the capability was assayed to produce IAA. Keywords: Bacillus subtilis, Ganoderma boninense, growth-promoting, induce resistance, oil palm INTRODUCTION Basal Stem Rot (BSR) caused by Ganoderma boninense Pat is the main disease in plantation of oil palm (Elaeis guineensis Jacq) in Indonesia, including in Riau Province. The fungi can infect oil palm in all of stages, starting from seedlings to old plants (Priwiratama et al. 2014). The disease intensity will increase and can reach 40% on the second and third generation of oil palm plantation. In early infection, BSR can cause the end of oil palm production and reduce the weight of fresh fruit bunches (Susanto et al. 2005). Further infection, BSR can kill more than 80% of oil palm plants (Abdul Razak et al. 2004). There are many efforts to control the disease, such as using tolerance varieties. Basal stem rot has been controlled by using tolerance varieties, synthetic chemical fungicides, technical cultures, and biological control. However, the techniques have not been success (Prasetyo et al. 2008). BSR is difficult to control. Development of special disease control such as biological control is urgently needed. The advantages of using endophytic Bacillus as a biological control agent are that they can grow, proliferate and spread in plant tissue, stimulate the growth of plant, induce plant resistance by producing antibiotics and secondary metabolites (Zhao et al. 2015). Endophytic Bacillus, an inducer resistance agent, is a promising biological control agent to be developed to control the disease. Endophytic B. subtilis has been isolated from the oil palms. The use of endophytic bacteria isolated from oil palm root to control G.boninense has been conducted in vitro. The isolates are antagonistic to G. boninense and effectively inhibit the fungi at 50-55%. The ability of the bacteria to suppress the growth of G. boninense with a range from 8.13-49.38% has been reported (Nasahi et al. 2016). The bacteria could contribute to the growth of plants by increasing the leaf number and plant height in cocoa seedlings aged 3 months (Leite et al. (2013). The potency of B. subtilis as a resistant inducer agent in oil palm plantation has not been studied well. Therefore, the purpose of the study is to evaluate the capability of endophytic Bacillus isolated from the oil palm tissue to systemically induce the resistance of oil palm seedlings against G. boninense in the main seedling. MATERIALS AND METHODS Study area This research was conducted in Plant Disease Laboratory, Faculty of Agriculture and Biochemistry Laboratory, Faculty of Science, Universitas Riau, Pekan Baru, Indonesia from April 2016 to December 2017. Procedures The study in vitro was conducted in which it measured the concentration of salicylic acid in leaf extracts including the preparation of endophytic Bacillus isolates. The pure Bacillus endophytes used were re-isolated in the sterilized Nutrient Agar (NA) medium with a scratch method. One isolate of endophytic Bacillus was scratched on the NA media surface in a petri dish than it was covered by plastic