STUDY OF PHOSPHORYLATED RESIDUES OF LEPRK2 IN TOMATO AND THEIR FUNCTION IN POLLEN-PISTIL INTERACTIONS

SALEM, TAMARA; WENGIER, DIEGO; MUSCHIETTI, JORGE

Mar del PLata

Congreso; SAIB 2007; 2007

SAIB

LePRK1 and LePRK2 are two pollen-specific receptor kinases from Solanum lycopersicum, of pollen tubes and potentially involved in pollen-pistil interactions. Transduction, by their kinase activity, of a pistil signal might initiate a signalling cascade in the pollen tube that regulates its growth. LePRK2 is phosphorylated in vivo in pollen membranes. To determine which LePRK2 residues are phosphorylated in vivo, we separated proteins from germinated pollen, by 2D gels. To visualize the phosphorylated isoforms, we performed western blots using an antibody against LePRK2. Spots corresponding to those isoforms were isolated from a Coomassie blue stained 2D gel. Another strategy involves computational approaches to predict phosphorylation sites in LePRK2. We selected 8 serines or treonines of LePRK2: S277, S279, S282, S304, S307, T308, T358 and S396. To study their functional relevance during pollen tube growth, we substituted them by Alanines using wild-type pLAT52-LePRK2-eGFP vector in mutagenesis, followed by transient expression in tobacco pollen. We previously showed pollen tubes that received wild type LePRK2-eGFP, displayed aberrant ballon tip morphology at germination. On the contrary, pollen tubes transfected with the construct that had A277, 279, 282, recovered the wild type phenotype. These results will be further studied and complemented by the proteomic approach.