Dissecting the contributions of effector proteins SAP11 and SMP11 to phytoplasma symptom development in Arabidopsis and Maize

Resumo

Phytoplasmas are vector-borne bacteria associated with various plant diseases. They have virulence proteins that interfere with plant development and aid disease spread in nature by affecting plant defenses against vectors. This project builds on functional data for the Aster yellows phytoplasma strain Witches' Broom (AY-WB), which secretes a virulence protein SAP11 that alters plant development in Arabidopsis and vector-plant interactions, by degrading TCP plant transcription factors. The goal is to investigate the contribution of SAP11 homologue (SMP11) to the virulence of Maize bushy stunt phytoplasma (MBSP), an important pathogen of Zea mays L. To pursue this goal, we will (1) investigate if SAP11 and SMP11 interact with various classes of Arabidopsis and maize TCPs, (2) study variations in genome and SMP11 sequences and symptom induction of MBSP isolates, and (3) identify TCP protein sequences that are involved in interactions with SAP11/SMP11. We expect to determine which sequences ín SAP11 and SMP11 are involved in TCP binding and use this information to predict the specificity of SAP11 homologsin other phytoplasmas, as well as to determine tf SMP11 induce bushy symptoms in MBSP-infecfed maize, and influence the reproduction of the leafhopper vector, Dalbuius maidis. From objective 2, we hope to identify variation in SMP11 genes among MBSP strains and how they may interact with the plant host TB1/C1N-TCP transcription factors resulting in symptoms and increased maize susceptibility to D. maidis. Finally, in objective 3 we will have identified the TCP domains/residues that are involved in SAP11/SMP11 binding and SAP11/SMP11-mediated destabilization, and also have collected information for generating transgenic maize lines that are more resistant to MBSP. (AU)