5-4.1. Introduction

Agrobacterium is considered as the nature’s genetic engineer. Agrobacterium tumefaciens is a rod shaped, gram negative bacteria found in the soil that causes tumorous growth termed as crown gall disease in dicot plants (Figure 5-4.1.). The involvement of bacteria in this disease was established by Smith and Townsend (1907).

Figure 5-4.1: Tumor induced by Agrobacterium in plants

Agrobacterium contains a transfer DNA (T-DNA) located in its tumor-inducing (Ti) plasmid that is transferred into the nucleus of an infected plant cell. The T-DNA gets incorporated into the plant genome and is subsequently transcribed. The T-DNA integrated into the plant genome carries not only oncogenic genes but also opine synthesizing genes.