Overexpressing peach PpePAO1 gene improves the nutrient value of tomato and enhances resistance against Botrytis cinerea

Polyamine oxidase (PAO), which catalyzes the catabolism of spermidine and spermine, is involved in fruit ripening and pathogen response. However, the function of PAO in fruit quality and disease resistance against Botrytis cinerea (B. cinerea) is still unclear. The effect of polyamine oxidation on tomato fruit quality and disease resistance against B. cinerea was investigated. Overexpressing peach PAO gene PpePAO1 increased ethylene production and accelerated fruit ripening of transgenetic lines. The ascorbic acid (AsA) and lycopene contents were dramatically higher in transgenic lines. The transgenic lines exhibited a much lower disease incidence and smaller lesion area after incubation of B. cinerea. The contents of H2O2 and O2•− in transgenic fruits were much higher than control after infection, and an ROS burst and PCD were observed in the infection site of transgenic leaves. Furthermore, the activity of the antioxidases SOD, POD, CAT and APX were higher in transgenic lines after infection. The expression of AsA biosynthesis-related genes in transgenic lines was significantly higher than control. Taken together, our study highlights enhancing polyamine oxidation as a novel approach for improving the nutritional value of tomato and resistance against B. cinerea.