EVIDENCE FOR IN-VITRO INTERACTIONS BETWEEN BUD AND PARENCHYMA IN JERUSALEM-ARTICHOKE TUBERS DURING BREAKING OF DORMANCY PROMOTED BY 2 N-ACETYLHEXOSAMINES - EFFECT ON MEMBRANE LECTIN LOCALIZATION

Fragments of parenchyma (with or without bud), taken from dormant tube rs of Helianthus tuberosus, were cultured in vitro at 24 degrees C on a mineral medium containing firstly N-acetylgalactosamine then N-acety lglucosamine. This sequential treatment induced after 6 days of cultur e the formation of soluble and active substances promoting the breakin g of dormancy. At the same time the hexosamines induced the decrease o f membrane lectins within the parenchyma while these lectins are incre ased within the bud. The biological role of hexosamines is discussed.