P-144 - Predicted effector SAP11-like of 'Candidatus Phytoplasma solani' alters phenotype of transformed Arabidopsis thaliana plants and interacts with transcription factors AtTCP2 and AtTCP4

In plant pathogenic bacteria, effector genes encoding small proteins that affect plant development and physiology are frequently found. In our previous genomic studies of several ‘Candidatus Phytoplasma solani’ strains we predicted an array of putative effector genes, including homologues of previously characterized ‘Ca. P. asteris’ effectors, such as SAP11 and SAP54. In the scope of this study, we aimed to characterize ‘Ca. P. solani’ SAP11-like effector by investigating its influence on Arabidopsis thaliana growth and development, and its possible interaction with plant transcription factors (TCPs). Codon-optimized SAP11-like effector gene was introduced into arabidopsis by floral dip followed by regeneration of transgenic lines. In order to detect possible interactions between SAP11-like and AtTCP2 and AtTCP4, in planta bimolecular fluorescence complementation (BIFC) assays were performed in agroinfiltrated Nicotiana benthamiana leaf cells and visualized by confocal microscopy. Our results have shown that ‘Ca. P. solani’ SAP11-like effector significantly affected phenotype of transformed arabidopsis plants by inducing changes such as reduction of leaf size and leaf crinkling, reduced biomass, excess of axillary branches, changes in siliques and root morphology. Moreover, BIFC assays detected interaction of SAP11-like effector with AtTCP2 and AtTCP4. To the best of our knowledge, this is the first report of characterization of ‘Ca. P. solani’ effector-host interaction.