Control of post-harvest gray mold (Botrytis cinerea) on grape (Vitis vinifera) and tomato (Solanum lycopersicum) using volatile organic compounds produced by Xenorhabdus nematophila and Photorhabdus laumondii subsp. laumondii

Abstract

Post-harvest fruit and vegetable rot produced by Botrytis cinerea (Helotiales: Sclerotiniaceae) causes significant reductions in food availability and drastically increases economic losses. The use of microbial-based tools for pathogen management holds promise. In particular, volatile organic compounds (VOCs) emitted by microbes (e.g., bacterial compounds) are becoming increasingly more frequent as an alternative to chemical and physical treatments. In this study, we performed three laboratory experiments to investigate the effects of VOCs emitted by two gram-negative entomopathogenic bacteria, Xenorhabdus nematophila, and Photorhabdus laumondii subsp. laumondii, on the infection and growth of the pathogenic mold B. cinerea on post-harvest red grapes and tomatoes. In addition, we evaluated the preventive effects of these bacterial VOCs against pathogens in post-harvest wounded and intact grapes. Overall, VOCs emitted by X. nematophila and P. laumondii limited the lesion area of B. cinerea to 0.5% and 2.2%, respectively, on the grapes. Similarly, VOCs emitted by X. nematophila and P. laumondii limited the lesion area of B. cinerea to 0.5% and 0.02%, respectively, in tomatoes. In addition, the emission of VOCs by both bacteria showed strong preventive fungal effects. In particular, VOCs emitted by P. laumondii reduced to 13% B. cinerea incidence in damaged grapes exposed to VOCs. Moreover, intact grapes exposed to VOCs emitted by X. nematophila and P. laumondii decreased B. cinerea incidence by 33%. This study provides insightful information about a potential novel bacteria-based tool that can be used as an alternative in the integrated control of post-harvest diseases.