Histochemical localisation of carboxylesterases in roots of Lycopersicon esculentum in response to Meloidogyne incognita infection

A cytochemical study of esterase activity of tomato cultivars resistant (VFN8) and susceptible (Roma) to the root-knot nematode Meloidogyne incognita has shown activity present in root tissue of both cultivars. Inhibitor studies indicated the likely involvement of carboxy- and acetyl-esterases as components in the prostele and cortical cells of cv. Roma 1, 2, and 3 days after nematode infestation. In contrast, necrotic cells immediately adjacent to the nematode in roots of VFN8 were seen to contain high levels of phenolics by 3 days after infection with the adjacent cells having high levels of carboxylesterase activity. The possible role of the enzyme in the hypersensitive response of tomato plants during nematode infection is discussed.