321 A TOOL FOR MONITORING Trichoderma AND Fusarium oxysporum f.sp. elaeidis OIL PALM INTERACTIONS, USING CONSTITUTIVE AND INDUCIBLE GREEN FLUORESCENT PROTEIN (GFP) AND RED FLUORESCENT PROTEIN (DsRED) REPORTER SYSTEM RUSLI, M H*; IDRIS, A S* and COOPER, R M** ABSTRACT Vascular wilt disease of oil palm is cause by Fusarium oxysporum f.sp elaeidis. The pathogen normally invades intact roots of palms or wounds and colonises the xylem vessels where it causes water stress, and hormonal imbalance result in severe yield loss and possible palm death. This study attempted to visualise the stages of colonisation and penetration into roots by Fusarium oxysporum f.sp elaeidis expressing Red Flourescent Protein (DsRed) in susceptible oil palm line and it’s interactions with Trichoderma TPP4 expressing Green Fluorescent Protein (GFP). Trichoderma TPP4 and Fusarium oxysporum f.sp elaeidis were successfully transformed using Agrobacterium tumefaciens-mediated transformation with both GFP and DsRed respectively using vectors pCAMDsRed and pCAMBgfp whereby this is the first report that Fusarium oxysporum f.sp. elaeidis has been genetically modified. Analysis showed that early colonisation of Foe hyphae on the surface of secondary roots while colonisation by Trichoderma was observed at early stages after inoculation and became denser with time. Trichoderma TPP4 also was seen coiling around the Foe when inoculated together showing potential mycoparasitisic action. Keywords: Fusarium oxysporum f.sp. elaeidis (Foe), Trichoderma, Green Fluorescent Protein (GFP), Red Fluorescent Protein (RFP). Date received: 21 May 2018; Sent for revision: 21 May 2018; Received in final form: 18 October 2018; Accepted: 12 March 2019. A TOOL FOR MONITORING Trichoderma AND Fusarium oxysporum f.sp. elaeidis OIL PALM INTERACTIONS, USING CONSTITUTIVE AND INDUCIBLE GREEN FLUORESCENT PROTEIN (GFP) AND RED FLUORESCENT PROTEIN (DsRED) REPORTER SYSTEM * Malaysian Palm Oil Board, 6 Persiaran Institusi, Bandar Baru Bangi, 43000 Kajang, Selangor, Malaysia. E-mail: mohd.hefni@mpob.gov.my ** Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, United Kingdom. INTRODUCTION Vascular wilt disease of oil palm is caused by Fusarium oxysporum f.sp. elaeidis (Foe) (Wardlaw, 1946). Fusarium vascular wilt is the most important disease of oil palm, endemic in western and central Africa including the Ivory Coast, Ghana, Benin, Nigeria, Cameroon and Congo Democratic Republic (Turner, 1981; Corley and Tinker, 2003; Cooper and Rusli, 2014). However, it remains an anomaly that vascular wilt disease has not occurred or been reported in Malaysia despite reported contamination of oil palm pollen and seed by F. oxysporum, F. solani and several other fungi that are associated with oil palm diseases (Flood et al., 1990). This is thought to be a result of other soil microflora that are antagonistic towards the disease-causing fungus (Mace et al., 1981) primarily Trichoderma and Gliocladium (Chet and Baker, 1981; Papavizas, 1985). Journal of Oil Palm Research Vol. 31 (2) June 2019 p. 321-330 DOI: https://doi.org/10.21894/jopr.2019.0009