ANATOMY AND PHENYLPROPANOID METABOLISM IN THE INCOMPATIBLE INTERACTION OF LYCOPERSICON-ESCULENTUM AND CUSCUTA-REFLEXA

A time-dependent correlation of anatomical and chemical defence reacti ons was shown during the incompatible reaction of tomato against the p hanerogamic parasite Cuscuta reflexa. Microscopical analysis of the in fection sites at the tomato stem revealed the elongation of epidermal, hypodermal and collenchymatic cells beneath the parasitic prehaustori um. After 9-11 days of infection the elongated cells had collapsed for ming a visible brownish plaque at the tomato stem followed by a scalar iform tissue with lignified and suberized cell walls. Concomitantly, a n enhanced accumulation of soluble phenolic compounds (chlorogenic aci d and an unidentified hydroxycinnamic acid derivative), as well as a s timulation of peroxidases, was observed. In contrast, PAL activity was not increased. Whereas the stimulation of phenylpropanoid metabolism could also be induced by artificial wounding, the described anatomical changes were only observed during attack of Cuscuta.