MOLECULAR-CLONING OF 2 TANDEMLY ARRANGED PEROXIDASE GENES FROM POPULUS-KITAKAMIENSIS AND THEIR DIFFERENTIAL REGULATION IN THE STEM

A genomic library was prepared from Populus kitakamiensis and screened with the cDNA for an anionic peroxidase from P. kitaknmiensis. One ge nomic clone was isolated that contained two tandemly oriented es for a nionic peroxidases, prxA3a and prxA4a. Both genes consisted of four ex ons and three introns; the introns had consensus nucleotides, namely, GT and AG, at their 5' and 3' ends, respectively. The prxA3a and prxA4 a genes encoded 347 and 343 amino acid residues, respectively, includi ng putative signal sequences at the amino-termini. Putative promoters and polyadenylation signals were found in the flanking regions of both genes. The sequence of the coding region of pvxA3a was completely ide ntical to that of the cDNA clone pA3, whereas the sequence of the codi ng region of prxA4a was only 73% identical to that of the cDNA clone p A3. Northern blot analysis showed that the patterns of expression of t he mRNAs that corresponded to prxA3a and prxA4a differed in stems of P . kitakamiensis.