توان باکتری Stenotrophomonas sp.-J29 در بیوکنترل عامل کپک سبز مرکبات

Citrus hold significant importance and economic value among tropical and subtropical products. The most critical postharvest storage disease in citrus is green mold, which annually causes substantial damage and is caused by the fungus Penicillium digitatum. Nowadays, biological control agents, particularly bacteria, are widely used in managing postharvest diseases. In this study, strain J29 from the collection of the Plant Pathology Department in Ferdowsi University of Mashhad was used for biocontrol tests. The growth of the pathogenic fungus in the presence of the bacteria, the volatile compounds produced by the bacteria, and the cell-free bacterial suspension were evaluated. The potential for reducing fungal activity was also assessed on Thompson variety oranges under laboratory conditions in the presence of the antagonist bacteria and compared with a control. For this purpose, 50 µl of bacterial suspension was inoculated into wounded, disinfected oranges, and after 24 hours, 30 µl of fungal spore suspension at a concentration of 105 were added to the wounded site. The fruits were kept under controlled conditions for one week. All experiments were performed with four replications in two separate trials. In the dual culture assay of the fungus and bacteria, 47% inhibition of P. digitatum growth was observed in petri dishes. In the volatile compounds assay in inverted petri dishes, 55% inhibition of fungal growth was recorded after one week. Additionally, in the evaluation of the cell-free bacterial suspension, the bacterial-free liquid culture medium was added to PDA medium at a 25% concentration, and the growth rate of the pathogenic fungus was assessed. Under these conditions, 50% fungal growth inhibition compared to the control was achieved. The treated fruits also showed a 70% reduction in green mold under in vivo assay. It seems that Stenotrophomonas sp.-J29 is a proper candidate for controlling citrus green mold. However, further comprehensive studies and evaluations under storage conditions are necessary.