The Ultrastructure and Histochemistry of a Nematode-Induced Giant Cell

Abstract

The development of giant cells induced by the nematode Meloidogyne in tomato roots has been followed under controlled growth conditions and the ultrastructure and histochemistry of these structures have been examined. Entry of the nematode larvae into the roots took place within 24 hours; giant cell formation started on the 4th day and involved breakdown of the cell walls accompanied by thickening of a surrounding giant cell wall and an increase in density and area of the cytoplasm. The nuclei increased in number by simultaneous mitosis throughout a single giant cell. The peak of cytoplasmic density was reached after moulting and during egg production. The rate of protein synthesis in the giant cell is correlated with the rate of growth of the nematode. The giant cell wall is a thick, irregularly surfaced structure which contains all the normal polysaccharide components of a cell wall. The cytoplasm is rich in protein and RNA and contains mitochondria, proplastids, Golgi bodies, and a dense endoplasmic reticulum. The nuclei are large and irregular in shape and contain large nucleoli and a number of Feulgen-positive bodies scattered irregularly along the nuclear envelope. The nucleolus contains RNA and fat as well as Feulgen-positive granules which are revealed after treatment with ribonuclease.

Studies on the Histopathological Responses of Vigna Mungo towards Meloidogyne Incognita at Different Time Intervals

“…The parenchyma cells, in neighbourhood of the nematode, specially near the head or whole body, were induced to become enlarged. Hypertrophy as a result of presence of the root-knot nematode has been reported by Bird [6], Mountain [9], Dropkin [10] on soybeans; Fawole [11] on white yam; Bhat and Hisamuddin [12] on bitter gourd; and Sayed et al [13] on mango roots.…”

“…The giant cells received metabolites and functioned as sink. The cytoplasm of the matured giant cell became dense and granular, and contained much protein [6]. Plant parasitic nematode, Meloidogyne incognita, takes its food from that multinucleate giant cell, where a group of small and large giant cells induced by the nematode is referred to as giant cell complex.…”

Differential vascularization of nematode-induced feeding sites

“…First, GCs originate from single cells. During their development, they retain their single cell identity, their cell wall thickens considerably, and their surface is further enlarged by cell wall protuberances, which results in a transfer cell-like appearance (13,28). Generally, transfer cells are found in tissues in which apoplastic transport is fundamental (29).…”

Interaction of Meloidogyne hapla and Rhizoctonia solani in alfalfa

“…The nuclei increase in number by simultaneous mitosis throughout a single giant cell (Bird, 1961). The nuclei are large and irregular in shape and contain large nucleoli (Bird, 1961). According to Christie (1936) the galls and cell division are believed to be caused by a secretion from the anterior end of the root-knot nematode.…”

“…The cytoplasm is dense ènd deeply staining, the cell walls are thick and the nuclei become enlarged (Schilke and Crittenden,. The nuclei increase in number by simultaneous mitosis throughout a single giant cell (Bird, 1961). The nuclei are large and irregular in shape and contain large nucleoli (Bird, 1961).…”