CATALASE INDUCTION IN GALLS PRODUCED BY MELOIDOGYNE-TOMATO ROOT INTERACTIONS IN VITRO
Susceptible and resistant tomato roots cultured in vitro were inoculated with avirulent and virulent populations of Meloidogyne spp. The interactions between M hapla and M. incognita with the susceptible tomato cultivar Roma VF were used as the standard compatible response, whilst the resistant tomato cultivars Cold-Set, Small-Fry and VFN8 were inoculated, respectively, with M. incognita, M. hapla and a virulent population of M javanica in order to have compatible responses producing galls. Galls were analyzed for their content of antioxidant enzymes, such as superoxide dismutase, Catalase and ascorbate peroxidase with respect to non-galled tissue. Catalase was induced in all the interactions tested when galls were fully developed at 50 days after inoculation with egg masses. SOD activity was higher in galls produced in susceptible roots and lower in those in resistant roots compared with non-galled tissue. Variation of ascorbate peroxidase activity during the infestation period in galls produced in the M. hapla-Roma VF interaction was similar to that of Catalase. The importance of such enzymes in the metabolism of root-knot galls is discussed.