Variation in Expression of Phytochrome B Gene in Cotton (Gossypium hirsutum L.)

Transgene integration and expression in host plant is quite unpredictable and is considered as the major problem in plant transformation. The variation in transgene copy number in transgenic plants influences the expression level and is one of such complication. In many plant species, the analysis of transgenic plants has shown that independent transgenic plants have one to many copies of transgenes. This study focused on molecular characterization of difference in copy number of transgenes and its impact on expression level on mRNA basis. Four advanced transgenic lines of phytochrome B were analyzed for the integration of the gene. These transgenic lines were taken out on the basis of difference in copy number as determined by Southern blot analysis and Fluorescence in situ hybridization (FISH) for transgene expression. Results taken by both real time PCR and Northern blot analysis determined high expression in Line QCC11 having two copies of transgenes in homozygous condition while the least expression was seen in lines QCC10 showing three copy number in heterozygous condition as multiple copies can be incorporated from one to few insertion sites.