Abstract

                                Southern root knot nematode, Meloidogyne incognita is an important nematode genus infesting okra growing tracts of Tamil Nadu. The present study was carried out to understand the cytological changes that occur during Meloidogyne incognita interaction with okra roots by employing Scanning Electron Microscope (SEM). The results exhibited the explicit changes in cellular structures of healthy and nematode-infested roots. The healthy roots possessed normal cell size for metaxylem, protoxylem, pith and cortex region nevertheless nematode infested roots revealed coalesced cellular structures. Root cell wall thickening, cell wall ingrowth, and starch granule accumulates of varying diameter were also observed in M. incognita infested okra roots, which were found to be the factors responsible for producing above ground symptoms during host-nematode interaction. Longitudinal imaging of nematode infested roots showed the nematode entry points of varying diameter along with adhered juveniles Juveniles on root topography and this was in contrast in M. incognita infested okra roots. Comparatively, these structures were absent in healthy roots.

Key words : Host- Nematode interaction; Okra roots-; Meloidogyne incognita; Ultrastructural changes; Scanning Electron Microscope (SEM)