Combined application of oligochitosan and Pichia carrbbica improves the disease resistance of postharvest tomato fruits

Our previous study showed that postharvest treatment of tomato with Pichia caribbica along with oligochitosan (OCH) significantly alleviated postharvest black spot of tomato fruit compared with P. caribbica alone. This study was to explore the effect of combined application of OCH and P. caribbica on disease resistance of tomato fruits through analyzing the activities of disease resistance-related enzymes, as well as transcriptome analysis of the fruit gene expression. Our findings indicated that P. caribbica, together with OCH, improved the activities of key enzymes associated with disease resistance in tomato fruit. Moreover, the combined application further upregulated the expression of genes involved in alpha-linolenic acid metabolism, the signal transduction pathways such as Ca2+, MAPK and plant hormone signaling pathways, resistant substance synthesis, and ROS metabolism, which improved the fruit disease resistance. Considering the significance of these results, OCH hold great potential for use in microbial biocontrol strategies against postharvest tomato diseases.