Multiple catechin effects in sour cherry during wound healing and defence

Flowers of sour cherry (Prunus cer ants L.) were grown in vitro on liquid M S-media containing IAA at 5.0 muM and BA at 0.8 muM (controls). The liquid medium was supplemented with catechin at 68 muM. The flowers were fixed on paper bridges with the petioles sticked into the liquid medium. Upon treatm ent with catechin large amounts of callus cells proliferated from the flowe rs. The fresh weight was 18 fold that of controls. Young fruit tissue of so ur cherry (P. cerasus) was cultivated on the same media as used for flowers . With added catechin the fresh weight of the fruit tissues was only 2.2 fo ld compared with controls. The catechin treatment showed formative cell div isions, in that already existing parenchyma cells themselves divided about 2-6 times. The number of subdividing cells per unit area was 4.3 times that of controls. In contrast, the controls showed significantly more leaching of flavanols into intercellular spaces as compared with the catechin treatm ents. Additionally, fungus-infected young cherry fruits were sampled in the orchard. Around the fungal lesions large parenchyma cells were found to su bdivide themselves several times transversely, similar to the fashion shown in the catechin-treated fruit pieces. Isoelectrofocusing of cherry-peroxid ases revealed inhibition of both basic and acidic isoperoxidases by catechi n. In the stressed wound area, leaching flavanols might act as inhibitors o f the extremely active IAA peroxidases. Additionally, the rapid oxidation o f the catechins as verified in our experiments is stimulative for cell deat h at the fungal infection site.