XVI International Botanical Congess

We cloned a cDNA encoding a lectin-like protein kinase from Populus nigra var. italica. The cDNA contained an ORF of 676 amino acids. The predicted polypeptide included following domains: a hydrophobic putative signal peptide at the N-terminus, a legume lectin homologous domain, a putative hydrophobic transmembrane domain and a C-terminal Ser/Thr protein kinase catalytic domain. The mRNA expression level of the protein kinase was higher in roots, mature leaves and calli than in young leaves and apical buds of poplar. Although a trace of the transcript was observed in the young leaves, the transcript was increased one hour after punching. Spraying the young leaves with water also induced the gene expression. The C-terminal domain of the protein kinase showed auto- and casein phosphorylating activities in the presence of Mn2+. Phosphoamino acid analysis revealed that Ser and Thr residues of the kinase were autophosphorylated.