A Possible Role for a-tomatine in the Varietal-specific Resistance of Tomato to Cladosporium fulvum

Phytoalexins: Enzymology and Molecular Biology

“…Agglutination of potato protoplasts by elicitor preparations indicates elicitor binding sites at the protoplast surface (666). Binding of radiolabeled culture filtrate molecules from Cladosporium fulvum to cell membranes of Lycopersicon esculentum has been reported (628,664). Race-specific oligosaccharide suppressors of the glucan elicitors of Phytophrhoru infesruns appear to compete with elicitor for binding sites present in microsomal membrane preparations from Sohnum ruberosum (641).…”

Preformed Antimicrobial Compounds and Plant Defense against Fungal Attack

“…No preferential accumulation of a-tomatine was seen in resistant interactions when compared with compatible interactions, leading to the conclusion that a-tomatine does not appear to have a role in variety-specific resistance (although these experiments are complicated by the fact that both of these fungi are able to degrade a-tomatine enzymatically). However, it has been suggested that a-tomatine may play a secondary role in the variety-specific resistance of tomato to incompatible races of the biotroph Cladosporium fulvum and that release of the saponin from leaf cells as a consequence of an incompatible interaction may act to kill or contain the pathogen (Dow and Callow, 1978).…”

Pantothenate synthetase from Fusarium oxysporum f. sp. lycopersici is induced by α-tomatine

“…First, tomatine stimulates sporulation in vitro (Smith and MacHardy 1982) which implies a high energy demand. Secondly, the toxic eects of tomatine, as mentioned above, are attributed to its ability to form complexes with membrane sterols (Safe et al 1977;Dow and Callow 1978;Roddick 1979;Roddick and Drysdale 1984;Steel and Drysdale 1988;Keukens et al 1995). Thus, it is reasonable to envisage a scenario in which the sterol components of the membrane are depleted and biosynthesis of fatty acids is increased in order to repair the damage to the cell membrane.…”