M-31 mutant (virA::Tn5) of Agrobacterium tumefaciens is capable of transferring its T-DNA into the nucleus of host cell, but incapable of integrating it into the chromosome.
An avirulent mutant (M-31 strain) was produced by the transposon (Tn5) mutagenesis of Agrobacterium tumefaciens (A-208 strain). A binary vector, pIG121-Hm, containing a kanamycin resistance gene (nptII) and beta-glucuronidase (GUS) gene with an intron, was introduced into M-31 and A-208 strains. The resultant Agrobacteria were inoculated onto leaves of Kalanchoe daigremontiana and to tobacco BY-2 cells to assay GUS activity to monitor the T-DNA transfer into the nuclei of host cells. The results indicated that T-DNA was transferred into the nuclei of cells of both host plants inoculated with the M-31 mutant. The M-31 mutant strain had an insertion of Tn5 in the virA gene on its Ti plasmid. The introduction of the virA gene in the M-31 mutant complemented its avirulent phenotype. No kanamycin-resistant cells were observed when the M-31 mutant harboring the pIG121-Hm was inoculated to tobacco BY-2 cells. The M-31 mutant (virA::Tn5) seems to transfer T-DNA into the nucleus of the host cell, but is unable to integrate it to the chromosome.
Majumder
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Department of Applied Biology, Faculty of Textile Science and Technology, Shinshu University, 3-15-1 Tokida, Ueda, Nagano 386-8567, Japan.
Yoshida
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Shioiri
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Nozue
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Kojima
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