Abstract:

A pair of primers were designed according to published Populus trichocarpa gene (PTD), and PtAP3, an AP3 homologous gene from P. tomentosa was isolated by PCR using genomic DNA of male clone of Populus tomentosa (L50) as template. The result indicated that the sequence was 1 813 bp (BamHⅠ and SacⅠ were introduced at the 5'and 3' end) including 7 exons and 6 introns, coding 238 amino acids. It was found to have 52%～82% homology to proteins from Lilium regale (AF503913), Petunia hybrida(AF230704), Gerbera hybrida (AJ009724), Rosa rugosa (AB055966), Malus domestica (AJ251116) and P. trichocarpa (AF057708) by blast analysis in GenBank. There was a highly conserved MADS-box motif in the protein of PtAP3, so it was putatived to be a transcription factor. The result of Southern blot analysis indicated that there were double copies of PtAP3 or two members which had a high homology to each other in P. tomentosa (L50, male) genomic DNA, and there was single copy PtAP3 in P.tomentosa (5082, female) genomic DNA. Sense and anti-sense expression vectors of PtAP3 were constructed by PCR and restriction enzymes digestion identification, and transformed into tobacco (Nicotiana tabacum) by Agrobacterium GV3101 and LBA4404. Some transgenic tobacco plantlets were obtained by PCR identification. The results above mentioned have provided important data to understand the molecular mechanism of male flower development of P.tomentosa, and also contributed to study on controlling flowering of P. tomentosa by gene engineering.

Key words: Populus tomentosa, APETALA3 homologous gene, cloning, transformation