Analysis of Genetic Variation of Transgenic Birch
转基因白桦的遗传变异分析

The occurrence of somaclonal variation in transgenic birch plants produced by infecting calli with Agrobacterium tumefaciens has been verified by cytological and RAPD analysis. The cytological analysis of transgenic plants showed that the frequency of non-diploid is 78.5%, and the non-transgenic control is 15.3%. The RAPD result indicated the transgenic plants' PI is 31.67.The comparison of data produced in previous analyses of transgenic poplar obtained by infecting calli with Agrobacterium tumefaciens ( PI is 57.82) showed that transgenic birch was characterized by fewer genomic changes. The reasons of somaclonal variation, including (1) tissue culture induced mutagenesis; (2) the foreign DNA may disrupt the gene it is inserted into or close to and may have multiple effects on other genes; (3) Antibiotic or herbicide-induced genomic DNA changes used as a selective agent in transformation protocols were discussed. The advice was suggested to reduce the variation frequency.