Phytoplasma effector SAP11 altered phosphate starvation responses and root architecture in Arabidopsis

Phytoplasmas have the smallest genome among bacteria and lack many essential genes required for biosynthetic and metabolic functions, they are phloem-limited plant pathogens. In this study the transgenic arabidopsis expressing the secreted aster yellows phytoplasma strain witches’ broom protein 11, shows an altered root architecture, similar to the symptoms of phytoplasma-infected plants, by forming hairy roots. This morphological change is paralleled by an accumulation of phosphate (Pi) and an increase in the expression levels of Pi starvation-induced genes and micro RNAs. In addition to the Pi starvation responses, secreted aster yellows phytoplasma strain witches’ broom protein 11 suppresses salicylic acid-mediated defense responses and enhances the growth of bacterial pathogens. These results contribute to an improved understanding of the role of phytoplasma effector SAP11 and provide new insights for understanding the molecular basis of plant-pathogen interactions.