Cell Responses to Heterodera Schachtii Feeding on Susceptible and Resistant Cultivars of Oil Radish

Abstract

Ultrastructural changes at feeding sites of the cyst nematode Heterodera schachtii Schmidt were examined in roots of a susceptible (Siletina) and three resistant (Pegletta, Nemex and Slobolt) cultivars of Raphanus sativus var. oleiformis grown in aseptic nutrient agar culture. Apparently identical changes occurred in both cultivars between 1 and 2 days after invasion by the infective second stage juveniles. Induced syncytia (nurse cell systems) derived from parenchymatous cells of the vascular cylinder showed ultrastructural features of high metabolic activity such as a pronounced increase in cytoplasmatic density, reduction of the central vacuole into numerous small vacuoles, abundance of ribosomes, polyribosomes, mitochondria, dictyosomes and enlargement of nuclei.