Histological Responses of Four Leguminous Crops Infected with Meloidogyne incognita

Histological responses to Meloidogyne incognita infection in Rhizobium nodules of clover, horsebean, lupine, and pea were investigated. The formation of giant cells in vascular bundles of nodules and roots, and the basal connection of the nodule, were usually associated with abnormal xylem and/or deformed xylem strands. However, giant cells did not disturb or prevent the development of nodular tissues. Areas in which galls formed, wall thickness of giant cells, and number of giant cells around the nematode head varied with plant species. Ranking by gall size and giant-cell wall thickness was horsebean > lupine and pea > clover. The multinucleate condition in giant cells resulted from repeated mitoses without subsequent cytokinesis. The resulting nuclei agglomerated in irregularly shaped masses in some giant cells.