Effects of a Mechanical Stimulation on Localization of Annexin-Like Proteins in Bryonia dioica Internodes

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Abstract
Mechanical stimulation exerted by rubbing a young internode of Bryonia dioica plants inhibits its growth. Previous cellular and biochemical studies showed that this growth inhibition is associated with Ca2+ redistribution and profound modifications of plasma membrane characteristics. We extracted and purified Ca2+-dependent phospholipid-binding proteins from B. dioica internodes. Two main proteins, p33 and p35, and other minor bands were isolated and identified as annexin-like proteins because of their biochemical properties and their cross-reactions with antibodies against maize (Zea mays L.) annexins. Rabbit antiserum was obtained by injection of B. dioica p35. This antiserum was used for the immunocytolocalization of annexin-like proteins in internode parenchyma cells. It appeared that the distribution of annexin-like proteins was different before and 30 min after the mechanical stimulation. Western analysis of proteins in membrane fractions after separation by free-flow electrophoresis showed that p35 was present in most fractions, whereas p33 appeared mainly in plasmalemma-enriched fractions after the mechanical stimulation. It is hypothesized that a subcellular redistribution of these proteins might be involved in growth inhibition by mechanical stress.