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Resistance

Relationship Between Ascorbic Acid and Resistance in Tomato Plants to Meloidogyne incognita. O. Arrigoni, Istituto di Botanica dell’Università and Laboratorio di Nematologia Agraria del Consiglio Nazionale delle Ricerche, 70126 Bari, Italy; G. Zacheo(2), R. Arrigoni-Liso(3), T. Bleve-Zacheo(4), and F. Lamberti(5). (2)(3)(4)(5)Istituto di Botanica dell’Università and Laboratorio di Nematologia Agraria del Consiglio Nazionale delle Ricerche, 70126 Bari, Italy. Phytopathology 69:579-581. Accepted for publication 7 December 1978. Copyright 1979 The American Phytopathological Society. DOI: 10.1094/Phyto-69-579.

The role of ascorbic acid in the defence mechanism of tomato (Lycopersicon esculentum) plants against attack by the root-knot nematode, Meloidogyne incognita, was studied under controlled conditions. The ascorbic acid concentration in roots of either nematode-resistant or -susceptible plants was varied experimentally and the reaction of these plants to attacks by the nematode was tested. A decrease in ascorbic acid, obtained by application of lycorine (an inhibitor of ascorbic acid synthesis), induces a reduction of plant resistance to the nematode, but an artificial increase in ascorbic acid concentration transforms susceptible plants into resistant ones. The amount of ascorbic acid in susceptible plants was unaltered by nematode attacks but in resistant plants ascorbic acid synthesis always was stimulated. It is suggested that ascorbic acid is utilized for the synthesis of mitochondrial hydroxyproline proteins which control the development of cyanide-resistant respiration.