virulence of Agrobacterium by "destruction" of one specific gene 
within the T-DNA, providing a means of transporting new genes 
into healthy plants. Specifically the destruction of the cytokinin 
gene within the T-DNA was accomplished by insertion into that 
gene of the genes encoding yeast (Saccharomyces cerevisiae) 
alcohol dehydrogenase I (ADH) and the bacterial aminoglycoside 
phosphotransferase gene from Tn5 which encodes for kanamycin 
resistance. This genetically engineered T DNA is called ADH-T- 
DNA. 
5 33 . Reproduction of the Plants 
The plants produced from the tissue culture (these plants are 
called HADH2) were then grown to sexual maturity, were allowed 
to flower, and were self-pollinated. Seeds were set and 
germinated. Many of the resulting seedlings tested produced 
nopaline, although the relative levels varied. An analysis of the 
DNA of the R1 progeny, using Southern hybridization, confirmed 
that the entire T-DNA was contained in the plants, although the 
copy number appeared to vary and occasional rearrangements of 
some T-DNA was observed. Reproduction by self-fertilization has 
been accomplished through more than four generations, and 
outcrosses have been conducted with commercial tobacco 
varieties. The T-DNA has been retained throughout these crosses 
as indicated by nopaline presence. 
Environmental Assessment 
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