Galls from Calliandra brevipes BENTH (Fabaceae:Mimosoidae): evidence of apyrase activity contribution in a plant-insect interaction

By western blots, cross-immunoreactivity with polyclonal anti-potato apyrase antibodies identified the Calliandra brevipes apyrase as a band of 75 kDa in the tissues of non-galled stem and leaves, and those of globose galls. The non-galled tissues hydrolysed either ATP, ADP, UDP, GTP or GDP. In globose galls, ADP, UDP and GDP hydrolysis were 1.7-5.1-fold higher than in non-galled tissues. ADP and UDP hydrolysis either from non-galled or globose gall tissues were 10-38% stimulated by 5 mM calcium, and drastically reduced (66-99%) by the addition of 5 mM EDTA or EGTA, confirming the divalent cation dependence. Nucleotidase, phosphatase or ATPase activities contributed in lower reaction rates. Apyrase activity was confirmed in C. brevipes tissues by nondenaturing polyacrylamide gel electrophoresis and western blots. By histochemical techniques, the ADPase activity was found as a granular-dense lead phosphate deposit homogeneously distributed at the external surface, and inside the nutritive cells of the globose gall. The sites of polyclonal anti-potato apyrase antibodies corroborate these localisations. The globose galls of the C. brevipes stems increase their capacity of hydrolysing nucleotides, which could be associated with carbohydrate biosynthesis, signalling and/or cell proliferation, crucial for feeding and survival of the insect.