Mosaic expression pattern of the nptII gene in transgenic tobacco plants Nu 21

Mosaic patterns of transgene expression in plants

“…Mosaic manifestation of the marker genes among the first generation progeny from self pollination of the initial transformants was also reported elsewhere [16,19,33,34]. Mosaic pattern of the gfp gene expres sion under control of the CaMV 35S RNA promoter was described for the tobacco plants containing multi ple transgene copies and representing first and second generation progeny of self pollination.…”

“…Among the 138 initial transformants of A. thaliana, 38 plants (23.1%) the appearance of plants with the traits of partial nptII silencing at the level of somatic tissues, which resulted in the escape from the expected Mendelian segregation [33]. Ear lier, we described mosaic pattern of the nptII expres sion in somatic cells of transgenic tobacco plants Nu 21 [16]. Inheritance of this phenotype upon transfor mant selfing in Т 1 -Т 4 and in F 1 hybrids from crossing of the first and second generation plants with the wild type was demonstrated.…”

“…Relative to the frequency of the mosaic progeny appearance, three groups of plants can be distinguished, including the group with low fre quency of mosaic progeny (0 to 21.8%); the group with high frequency (63.1 to 100%); and the interme diate type, where the frequency varied within the wide range of 0 to 100%. It is noteworthy that even in cases that the plants chosen on kanamycin containing medium as parents were green, in the following selfed generation, as well as in F 1 from crossing with non transgenic tobacco, the appearance of plants with leaf variegation was again detected on kanamycin con taining medium [16]. It was demonstrated that the exogenous DNA insert in the genomes of the Nu 21 plants had complex structure and was organized in the form of two presumably full length copies in the head to tail orientation, and one truncated copy between them, in reverse orientation.…”

“…For example, in tobacco leaf blade these sectors can be either found in the L2 and L3 cell layers [18,21], or randomly distrib uted in all layers [16,19,21]. Nonclonal variegation pattern of the sectors with active and inactive trans gene/endogenous genes was demonstrated in petunia plants upon posttranscriptional silencing [2,20].…”

“…For example, blotched leaf pig mentation (alternation of white and green spots on the leaf blade) in transgenic plants carrying the nptII gene on selective medium [1,16]; seedling and leaf blotch revealed by histochemical staining in transgenic plants with the uidA gene [17,18]; irregular fluorescence of plant tissue sectors in case of insertion of the gfp gene (green fluorescent protein GFP) [19]; and variegated pigmentation of corolla in petunia plants transformed with the chs and dfr genes, and the maize A1 gene [2,3,20].…”