Pichia caribbica improves disease resistance of cherry tomatoes by regulating ROS metabolism

• P. caribbica decreased the occurrence of black spot in postharvest cherry tomatoes. • The production rate of O 2 ¯ · and the contents of H 2 O 2 and MDA were reduced. • P. caribbica increased SOD, POD and CAT activities in cherry tomatoes. • P. caribbica stimulated AsA-GSH cycle, GPX cycle and GST activity in cherry tomatoes. Black spot caused by Alternaria alternata is one of major diseases of postharvest cherry tomatoes. This study intends to investigate biocontrol efficacy of Pichia caribbica against black spot and explore the mechanisms involved in improved disease resistance of cherry tomatoes through analyzing reactive oxygen species (ROS) metabolism. The results demonstrated that P. caribbica significantly decreased the occurrence of black spot in cherry tomatoes. P. caribbica improved the activities of enzymatic system for ROS scavenging in cherry tomatoes, including some antioxidant enzymes, the enzymes in ascorbic acid-glutathione (AsA-GSH) and glutathione peroxidase (GPX) cycles, and glutathione S-transferase (GST). Furthermore, P. caribbica maintained the high level of the key antioxidant substances and then decreased the production rate of O 2 ¯ ·, the contents of H 2 O 2 and malondialdehyde (MDA). These results revealed that P. caribbica induced the enzymatic and non-enzymatic systems to remove ROS, and then improved the disease resistance of cherry tomatoes against pathogen. This study will provide new strategy for controlling postharvest disease of fruits and vegetables by improving the ability of ROS scavenging to defense against pathogens.