Sucrose enhances the expression of a CDPK in excised leaves of wheat

MARTÍNEZ-NOËL G; TOGNETTI J; PONTIS H

Iguazú

Congreso; XL Reunión Anual SAIB; 2004

SAIB

In a previous work we have shown the involvement of the second messenger calcium and Ser/Thr protein kinases (PK) in the process that leads to the induction of fructan synthesis by sucrose in wheat (Triticum aestivum). Based on these results, we cloned from wheat leaves treated with sucrose, a complete cDNA with an ORF, 1828 nt long from the ATG to the stop codon, encoding a 58.4-kDa predicted protein homologous to plant calcium-dependent and calmodulin-independent PK (CDPK) (gi: 47522359, TaCDPK1). The deduced amino acid sequence showed all the CDPK characteristic domains and putative consensus motifs for Nmyristoylation and phosphorylation. We demonstrated by RT-PCR and real-time PCR that TaCDPK1 expression is induced by sucrose. Besides, specific inhibitors of calcium channels, Ser/Thr PK and protein phosphatases (PP), which were shown to be effective on suppress sucrose induction of fructan synthesis, also blocked the sucrose effect on the accumulation of TaCDPK1 transcripts. Also, the inhibitors decreased the basal gene expression. These results suggest that the putative components of the sucrose signaling pathway -calcium, PK and PP2A- are required for upregulation of TaCDPK1 by sucrose. Further studies are necessary to understand whether TaCDPK1 is a specific target of sucrose regulation or it is a component of the sugar signalling cascade. Supported by ANPCyT, FIBA and UNMdP.