Mor, M., Dept. of Entomology and Nematology, ARO, Volcani Center, Bet Dagan 50520, Israel
Oka, Y., Nematology Unit, ARO, Gilat Research Center, M.P. Negev 85280, Israel

Feeding sites induced by the root-knot nematode Meloidogyne artiellia in turnip (Brassica rapa), cabbage (Brassica oleracea) and barley (Hordeum vulgare) were examined by light and electron transmission microscopy, and compared with those formed by M. javanica and M. hapla. The feeding cells of M. artiellia in turnip and cabbage showed hypertrophy, hyperplasia and vacuolization, and became multinucleate giant cells. In contrast to the typical simple-shaped giant cells of M. javanica and M. hapla, those of M. artiellia had an amoeboid structure containing 'protuberances', which are distinct from previously reported 'projects' of giant cells induced by M. incognita in other plants. Protuberances expanding between vascular cells were observed in young and developed giant cells. Since no cell-wall fragments were found at the bases of the protuberances, either by light or electron microscopy, it is strongly indicated that these structures were caused by local expansion of the giant cells rather than by fusion with adjacent cells. The giant cells of M. artiellia in barley had regular shapes of giant cells without protuberances, and resembled those induced by M. javanica or M. hapla in turnip and cabbage.