Presence of Indole compound in nematode galls

Abstract

Multi-nucleate structures or giant cells in plants infected by root-knot nematodes are believed to arise in response to substances emanating from the parasite. DuCharme stated that the resulting tumours and galls are due to reactions of the host plant and might be considered as a kind of defence mechanism. According to him, growth-stimulating substances, presumably released by the nematodes, lead to hyperplasia of the pericycle and root tip if citrus. Krusberg found that tryptophan, the precursor of indole, is present in the nematodes infected or nematode-free callus tissues and also in the galls caused by Ditylenchus dipsaci (Kuhn) Filipjev on alfalfa roots. According to Goodey, Wallace suggested that formation of giant cells in roots attacked by Heterodera spp. and Meloidogyne spp. might possibly be due to the presence of growth hormones. The experiment reported here was undertaken to examine whether any indole compound is present in the galled tissues of nematode-infected plants.