Variation in the responsiveness of induced resistance against Pseudomonas syringae pv. tomato by Solanum lycopersicum treated with para-aminobenzoic acid

Para-aminobenzoic acid (PABA) induced resistance against Pseudomonas syringae pv. tomato in Solanum lycopersicum. Fertilizer application was necessary for induced resistance and only two out of eight breeding lines showed PABA-induced resistance. A comparison of gene expression between a PABA-responsive and PABA-non-responsive line showed that either the responsive line had a faster and stronger increase in expression or the responsive line showed increased expression due to PABA. Although PABA affected SA-related gene expression, changes in gene expression were not always directly related to the responsiveness to PABA. The response to PABA by SA, JA and ET-related mutants showed SA dependence. Factors, such as fertilization practices and host genotype, are important considerations in the development of PABA as a disease management product.