Exploration and Selection of Potential Epiphytic Yeasts to Control Fusarium Fujikuroi cause of Bakanae Disease in Rice Plants

Abstract

Bakanae disease on rice is caused by Fusarium fujikuroi which can cause yield losses ranging from 3.0-95.4%. Epiphytic yeasts have been known as biological control agents for plant pathogens. The purpose of this study was to determine the potential of epiphytic yeast derived from rice leaves to control bakanae disease. The study consisted of several stages, namely: 1). Exploration of epiphytic yeasts in 3 districts in West Sumatra, namely Pesisir Selatan, Solok and Tanah Datar 2). Selection epiphytic yeasts based on morphological characteristics and pathogenicity 3). Testing the ability of epiphytic yeasts to control F. fujikuroi using the dual culture and Sealed Plate Methods 4). Testing epiphytic yeasts to control F. fujikuroi from infected rice seed and 5). Molecular identification of potential epiphytic yeast isolates for controlling F. fujikuroi. Forty-two yeast isolates were successfully explored, isolated and characterised. Then they were tested for their ability to suppress the growth of F. fujikuroi by using the dual culture method and 14 isolates were obtained which had an inhibitory power above 50%. Then, these 14 isolates were tested for their ability to produce volatile compounds and control F. fujikuroi in vivo. The percentage of inhibition of epiphytic yeast against F. fujikuroi using dual culture and Sealed Plate Methods were range from 55.12 – 86.00% and 32.35- 73.03% respectively.  The results of in vivo study showed that treatment of rice seeds with epiphytic yeast isolates reduced ungerminated seeds, infected seedlings except (KS3, KTD8, KS6) and disease severity with the percentage of inhibition of (25.84-100%), (13.26-21.42%) and (31.77- 44.18%) respectively.  There were 4 epiphytic yeast isolates that had high potential in suppressing the growth of F. fujikuroi in vitro and in vivo studies, namely KS2, KTD1, KTD6, and KS6, molecularly identified as Candida parapsilosis, Moesziomyces antarcticus, Pseudozyma churashimaensis and Moesziomyces antarcticus respectively.