Catalase inhibition as a biochemical marker of resistance to root-knot nematodes in tomato

Resumen

Three tomato cultivars carrying the gene Mi-1, which confers resistance to root-knot nematodes, were compared to susceptible counterparts in terms of nematode reproduction and changes in catalase activity of roots due to nematode infestation. The resistant cultivars did not allow nematodes to reproduce significantly and maintained optimal growth parameters, whilst great nematode development and reproduction, along with loss of plant fitness, were observed with the susceptible cultivars 40 days after inoculation. The resistant response was constantly associated with an inhibition of catalase activity in root extracts five days after inoculation, whilst such a change in enzyme activity was lacking in infested susceptible cultivars. Ultrafiltration of root extracts was carried out to get rid of free phenol and, in particular, salicylic acid. Such treatment did not alter catalase inhibition in roots during the early stages of the incompatible plant-nematode interactions considered. The opportunity to use the method described in screening for resistance of core collections of tomato is discussed.