Effect of Fusicoccin on Sucrose Exchanges Between a Host, Pelargonium zonale, and a Higher Parasitic Plant, Cuscuta reflexa

Abstract

The sucrose exchange characteristics at the level of contact between a host, Pelargonium zonale (L.) Aiton, and a parasite, Cuscuta reflexa Roxb., were investigated by studying the effects of fusicoccin (FC). With isolated haustoria of Cuscuta, FC stimulated the activity of the plasma membrane ATPase. This action was established by FC-increased proton extrusion. FC-increased O₂ consumption and FC-increased 86Rb uptake. Nevertheless, FC strongly inhibited (by 30-50%) sucrose uptake and strongly enhanced (by 42-47%) sucrose release. These results, which are discussed in relation to the physiology of the association between host and parasite, outline the very special properties of the haustorium of Cuscuta.