Abstract:

As the core component of RNA induced silencing complex (RISC), Argonaute (AGO) proteins play an essential role in plant development and cellular metabolism. Our previous studies suggested that a predicted gene from Populus trichocarpa genome sequence, POPTR_0001s22120.1, was preferentially expressed in adventitious root development of Populus cuttings. In this study, the target cDNA clones were isolated from the cDNA library prepared from adventitious roots of P. × euramericana and P. deltoides using RT-PCR technique, respectively. The two cDNAs were both 2 809 bp, and would encode for polypeptides of 907 amino acid residues with the molecular mass around 102.31 ku and 102.34 ku, the theoretical isoelectric point (pI) of 9.34 and 9.7, respectively. There is difference in seven distinct amino acid residues between the two deduced proteins which contain 3 conserved domains: DUF1785, PAZ and Piwi, and share 64.8% and 64.3% identify with AtAGO5 protein of Arabidopsis thaliana, respectively. They were, therefore, named as PeAGO5 and PdAGO5. Phylogenetic tree revealed that PeAGO5, PdAGO5, AtAGO1, AtAGO5 and AtAGO10 were assigned to the same clade. Quantitative real-time PCR analysis showed that PeAGO 5 was differentially expressed during adventitious root development in hardwood cuttings of the poplars, indicating that PeAGO 5 would be involved in adventitious root development.

Key words: Populus, hardwood cuttings, argonaute protein, expression pattern, qRT-PCR