Agrobacteria and Plants

Andrea PITZSCHKE (Salzburg): Plants are constantly surrounded by microbes. Many of these are harmful and thus pose a challenge on a plant´s stress management. The soil-borne pathogen Agrobacterium tumefaciens has the unique capability to transfer foreign DNA into plant systems. Gene transfer involves both bacterial and host factors. The timing and intensity of the bacterially activated host defense repertoire sets the switch to "yes" or "no" for a successful transformation. This repertoire is comprised of the specific induction of mitogen-activated protein kinases, defense gene expression, redox- and hormonal adjustments. The pathogen is equally smart: Agrobacterium tumefaciens abuses components of the host immunity system, it mimics plant protein functions and manipulates hormone levels to bypass or override plant defenses. The ongoing molecular battle between agrobacteria and attacked hosts will be discussed in relation to applied research.