Effectors that alter plant development and attract insect vectors are conserved among diverse phytoplasmas
S. HOGENHOUT (1) (1) John Innes Centre, United Kingdom

Phytoplasmas are highly diverse intracellular bacterial plant pathogens that are transmitted by sap-feeding insects. These bacteria are restricted to the plant phloem but nonetheless modulate a large range of plant processes leading to, among other phenotypes, witches’ brooms, phyllody (leaf-like flowers) and increased susceptibility of plants to insect vectors. We previously identified the effectors SAP11 and SAP54 from Aster Yellows Witches’ Broom (AY-WB) phytoplasma. SAP11 destabilizes Arabidopsis class II (CIN and CYC/TB1) TCP transcription factors resulting in witches’ brooms, altered leaf shapes and reduced jasmonate synthesis. SAP54 degrades MADS-box transcription factors leading to the production of leaf-like flowers. Both effectors promote insect vector attraction and reproduction. However, it is unclear how widely distributed these effectors are among phytoplasma species. We found SAP11 and SAP54 homologs in the genomes of diverse phytoplasmas that induce witches’ brooms and/or phyllody in a broad range of plant species. Intriguingly, SAP11 homologs show differential interactions with members of the TCP transcription factor family that correlate with the host ranges of the phytoplasma species. In contrast, SAP54 homologs target a core set of MADS-box transcription factors. Taken together, this research has uncovered how SAP11 and SAP54 effectors have evolved with diverse host systems and how they modulate phytoplasma transmission via attraction of insect vectors.


Abstract Number: P5-3
Session Type: Plenary