Gall induction on tomato root tips by Paralongidorus buchae: ultrastructural aspects

Abstract

A population of Paralongidorus buchae, Lamberti, Roca et Chinappen from Mauritius, fed exclusively on the root tips of tomato seedlings. As a response tips started to swell and became transformed into terminal galls three days after nematode inoculation. Electron microscopy studies of swollen root-tips revealed ultrastructural changes resembling those induced by Longidorus species. These included necrotic cells, where nematodes inserted their odontostyle and occurrence of a lysigenous cavity, as consequence of cell wall dissolution in the feeding site. In addition a cytopathic effect on the nuclei of the neighbouring cells was observed, such as synchronous mitosis, hypertrophy of nucleolus and occurrence of fibrillar bodies in the nucleoplasm. Unusual localization of cell wall thickenings was found in the meristematic tissue of the infested root tip, very close to the initial cells and also at a distance from the feeding site.