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DNA Transfer from Agrobacterium to Plant Cells in Crown Gall Tumor Disease

1998; Springer Nature; Linguagem: Inglês

10.1007/978-1-4899-1707-2_11

2542-8810

Anath Das,

Plant Genetic and Mutation Studies

Agrobacterium tumefaciens, a Gram-negative soil bacterium, causes crown gall tumor disease on most plants (Hooykaas and Beijersbergen, 1994; Zambryski, 1992; Kado, 1991; Ream, 1989; Nester et al., 1984). The bacterium infects plants at a wound site and forms tumors at the site of infection. Virulent strains of Agrobacterium contain a large tumor-inducing (Ti-) plasmid. Upon infection the bacterium donates a segment of the Ti-plasmid DNA, the transferred (T-) DNA, to the plant cell, where it is stably incorporated into the nuclear genome. Encoded within the T-DNA are genes for the biosynthesis of plant hormones auxin and cytokinin. Constitutive expression of these genes in a transformed plant results in an uncontrolled growth of cells, a cancerous phenotype. The related bacterium Agrobacterium rhizogenes causes the hairy-root disease that results from the stable transfer of the root-inducing (Ri-) plasmid DNA to plants. The process of DNA transfer from Agrobacterium to plants represents a naturally occurring gene transfer across a phylogenetic barrier.