Question

What is the role of agrobacterium for gene transfer in plants?

Answer 1

Agrobacterium tumefaciens is a soil bacterium and has Ti (Tumor inducing) plasmid. This bacterium invades crops and causes crown gall disease. Agrobacterium strains are modified by the removal of tumor inducing genes from the bacterium. T-DNA is the part of Ti plasmid transferred into plant cell DNA. The T-DNA which holds the desired foreign gene after splicing is introduced into the plant cell. The bacterial plasmid do not produce tumourous growth since the gene had been deleted. Once the T-DNA along with the spliced gene is introduced, it combines with the chromosome of the donor cell where it produces copies itself, by migrating from one chromosomal position to another. Through tissue culture methods, such plant cells are cultured, induced to multiply and differentiate to form into plantlets. The plantlets are transplanted to soil, where they are allowed to express the foreign gene introduced into them, when they multiply and grow in larger population.