The Initial Steps in Agrobacterium Tumefaciens Pathogenesis: Chemical Biology of Host Recognition

The biology of host recognition in Agrobacterium tumefaciens has set the tone for host interactions and xenognosis for several decades, and the twists and turns of the discoveries provide many valuable lessons and insights. From transposon mutagenesis enabling discovery of the initial chemical exchanges to two-component signal transduction and receptor identification, this organism continues to enrich our understanding of chemical ecology and pathogenic strategies. The complexity of the host commitment and the intricate nature of the evolved machinery remains awe inspiring. This system is now poised with the necessary chemical and biological resources, for both host and parasite, to reveal the detailed chemical biology that occurs within the host tissues. Here we review our current understanding of the signal exchanges, and highlight the many questions that remain to be addressed. We use this perspective to set the stage for the rich chemical biology this organism continues to offer..