Isolation and molecular characterization of cinnamate 4-hydroxylase from apricot and plum

Abstract

Cinnamate 4-hydroxylase (C4H) is the second enzyme in the phenylpropanoid pathway which participates in the synthesis of numerous phenylpropanoid compounds such as flavonoids, lignins, suberins and others. We identified a gene putatively coding for Class I C4H in apricot and plum and we analyzed the expression pattern of this gene under different apricot/plum graft combinations with different degree of compatibility. The full-length cDNA is 1 739 bp with a 1 515 bp open reading frame encoding a protein of 504 amino acids. Like other C4Hs, the predicted C4H polypeptides included conserved domains of cytochrome P450. The genomic sequence of the apricot C4H gene was interrupted by two introns 335 bp and 904 bp long. Several regulatory motifs including P-, A-, L- and H-boxes, which were conserved across phenylpropanoid metabolism-related genes in higher plants, were found in a 1 300 bp upstream promoter region of the apricot C4H gene. A phylogenetic analysis showed that all Prunus sequences clustered together and were closely related to Malus and Rubus C4H genes. The transcription of Class I PruC4H was detected in all the examined graft combinations, which suggested its rather constitutive character.