California tomato pathogens and fruit ripening

The main objective of this project is to establish the significance of fruit ripening softening for the susceptibility of ripe tomato fruit to four fungal pathogens important for the quality of fruit harvested in California: A. alternata, G. candidum, R. stolonifer and B. cinerea, which cause an enormous economic damage to a wide spectrum of crop species. Susceptibility of transgenic lines of tomato with suppressed expression of two cell wall degrading enzymes polygalacturonase (PG) and expansin(Exp) and non-ripening mutants lines Cnr, rin and nor were evaluated though the assessment of several parameter of the disease caused by each pathogen in light red fruit. This project begun on January 2010, and the results have shown that the four fungi do not all require the same ripening processes in order to infect fruit and suppression in both PG and Exp cell wall degrading proteins reduced the showed that tomato fruit with simultaneously reduced PG and Exp reduced the tendency to rot due to infections by these pathogens.  The project is currently set to do molecular analysis of these different lines of tomato when infection occurs, by analysis of genes involved in the cell wall disassembly metabolism, such as PMEs, XTHs, PGs.

The project was funded in 2010 and 2011 by the California Tomato Research Institute (CTRI)