Inhibition of Lasiodiplodia pseudotheobromae Causing Fruit Rot Disease of Longan by Using Antagonistic Bacillus siamensis RFCD306
Authors:   Division of Plant Pathology, Department of Entomology and Plant Pathology, Faculty of Agriculture, Chiang Mai University, Chiang Mai 50200, Thailand, Pipattanapuckdee Aimalin , Seehanam Pimjai ,   Division of Horticulture, Department of Plant and Soil Sciences, Faculty of Agriculture, Chiang Mai University, Chiang Mai 50200, Thailand,   Postharvest Technology Research Center, Faculty of Agriculture, Chiang Mai University, Chiang Mai 50200, Thailand,   Postharvest Technology Innovation Center, Ministry of Higher Education, Science, Research and Innovation, Bangkok 10400, Thailand, Tiyayon Chantalak ,   Division of Horticulture, Department of Plant and Soil Sciences, Faculty of Agriculture, Chiang Mai University, Chiang Mai 50200, Thailand,   Postharvest Technology Research Center, Faculty of Agriculture, Chiang Mai University, Chiang Mai 50200, Thailand,   Postharvest Technology Innovation Center, Ministry of Higher Education, Science, Research and Innovation, Bangkok 10400, Thailand, Boonyakait Danai ,   Postharvest Technology Innovation Center, Ministry of Higher Education, Science, Research and Innovation, Bangkok 10400, Thailand, Kunasakdakul Kaewalin ,   Division of Plant Pathology, Department of Entomology and Plant Pathology, Faculty of Agriculture, Chiang Mai University, Chiang Mai 50200, Thailand, Supakitthanakorn Salit ,   Division of Plant Pathology, Department of Entomology and Plant Pathology, Faculty of Agriculture, Chiang Mai University, Chiang Mai 50200, Thailand, Ruangwong On-Uma ,   Division of Plant Pathology, Department of Entomology and Plant Pathology, Faculty of Agriculture, Chiang Mai University, Chiang Mai 50200, Thailand,   Postharvest Technology Research Center, Faculty of Agriculture, Chiang Mai University, Chiang Mai 50200, Thailand,   Postharvest Technology Innovation Center, Ministry of Higher Education, Science, Research and Innovation, Bangkok 10400, Thailand
Published: January 2023

P ostharvest fruit rot disease of longan (Dimocarpus longan Lour.) caused by Lasiodiplodia pseudotheobromae is one of the most devastating problems for longan production in Thailand. To reduce the use of chemicals, the endophytic bacterium was isolated from healthy longan fruit for using as a biological control agent. The antagonistic bacterium Bacillus siamensis isolate RFCD306 which was identified based on morphological, biochemical and molecular characterization. It showed the antifungal effect with 94.40% of fungal growth inhibition which was conducted by a dual culture method. The efficacy of B. siamensis RFCD306 on the inhibition of fungal growth and conidial germination was observed under the scanning electron microscope (SEM) and revealed the abnormal germination of conidial and hyphal growth. Moreover, four antibiotic synthesis-related genes consisting of srfA, ituA, bacD and bymA were detected from B. siamensis RFCD306 by a polymerase chain reaction (PCR) technique. These genes might be involved in the antifungal activity of the antagonistic bacterium. Furthermore, the disease control efficiency of B. siamensis RFCD306 was evaluated on harvested longan fruits and showed that the bacterium decreased the incidence of fruit rot disease. Therefore, this study represented the effective B. siamensis RFCD306 for using as a biological agent in controlling postharvest fruit rot disease of longan.