Abstract: In this study, three clones of rolC-transgenic Malus robusta Rehd (having passed the gus and PCR examination) were used as materials for further research. Molecular hybridization was made to identify their integrated copy numbers and expression at transcription level. Southern hybridization demonstrated that rolC gene had been integrated in the genome of the three clones of rolC-transgenic Malus robusta Rehd, two of the three transformed clones had a single copy and another had double copies of the rolC gene integrated. In all the three transformed clones the rolC gene was integrated at different position in the plant chromosomal DNA. Northern hybridization demonstrated that different integrated copy numbers have influence on the expression of each rolC-transgenic clones, the clone with double rolC copies is less than the other two clones with a single rolC copy number on expression abundance at transcription level.The result of the biologic study demonstrated that: The three rolC-transgenic Malus robusta Rehd clones all need significant lower than the control on the propagation of shoot,rooting and regeneration of leave. The three rolC-transgenic Malus robusta Rehd clones all showed the characteristic rolC phenotype, such as dwarf shoot, shorter internodes, smaller leave area, shorter and more root.Among the three transgenic clones, it was found that the rolC gene integrated numbers and integrated location play an important role in the expression of the rolC-transgenic Malus robusta Rehd clones .

Key words: Malus robusta Rehd, rolC gene, copy number, biologic characteristic