The role of auxin-cytokinin antagonism in plant-pathogen interactions

On the one hand, Pto counter-regulates SA responses by producing higher in planta auxin levels (Figure 1). [...]increased auxin levels not only increase the concentration of JA but also enhance JA signaling [13], which in turn weakens the plant defense against biotrophic pathogens. [...]the conjugated forms of auxin also promote bacterial growth in the infected Arabidopsis plants by directly regulating the transcription of the virulence genes in Pto [19]. [...]auxin plays a pivotal role in shaping the hormonal dynamics of Pto-Arabidopsis interactions in favor of bacterial growth as well as efficient disease development. Pseudomonas syringae pv. tomato DC3000 (Pto) resides in the apoplast of adjacent Arabidopsis cells [30]. Besides other substances, the apoplast also contains various sugars, ions, and free hormones cytokinin and auxin (green and light blue chemical structures).