Ling Dong

   International Max Planck Research School

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PhD Thesis

started in Nov 2018
Specificity, phylogeny and fitness contributions of phytoplasma effector proteins
Friedrich-Schiller-Universität Jena, Genectics
First Supervisor: Prof. Dr. G. Theißen (Friedrich Schiller Universität Jena)
Co-Supervisor(s): Prof. J. Gershenzon, PD Dr. A. Mithöfer

Phytoplasmas are cell wall-less eubacteria that obligatory parasitize and replicate in two very different hosts, plants and transmitting insects. They occur in plants mainly in phloem tissue and require insects of the order Hemiptera for transmission. Phytoplasmas infect hundreds of plant species, including many important crops, and cause devastating diseases. Phytoplasma infected plants can display dramatic symptoms such as phyllody (transformation of floral organs into leaf-like structures) and witches’ broom syndrome (increase of the number of stems). These sympotms are caused by effector proteins that are secreted by phytoplasmas, the two best characterized being SAP11 and SAP54.
It has been shown that SAP11 and SAP54 target and degrade CIN-TCP-type transcription factors (CTFs) and MIKC-type MADS-domain transcription factors (MTFs), respectively. CTFs and MTFs are involved in many plant developmental processes, such as leaf and flower development. However, only a subset of the CTFs and MTFs are targeted by SAP11 and SAP54, respectively, and the molecular determinants of specificity remain largely unknown. We hypothesize that sequence differences between effector proteins have an influence on target protein specificity and hence plant phenotype diversity. To test it, we isolate SAP11 and SAP54 gene sequences from different phytoplasma species and strains of different host plants using e.g. PCR method. We also search for sequences of SAP11 and SAP54 homologs available in various databases and previous papers.
last updated on 2019-12-03