Establishment of a library of membrane and effector proteins of ´Candidatus P. mali´ to identify host-(apple)-pathogen interactions and to disrupt them

• Applicant: Dr. Kajohn Boonrod
• Subject Area: Plant Breeding and Plant Pathology ; Plant Physiology
• Term: from 2014 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 261316402

Candidatus Phytoplasma mali (´Ca. P.mali´) is a plant pathogenic phloem colonizing prokaryote causing apple proliferation, an economically important disease in apple in all European production areas with moderate climates. The disease is transmitted by insect vectors belonging to the genus Cacopsylla. Up to now the apple proliferation disease is controlled only by the application of insecticides. Until recently phytoplasmas have resisted all attempts of cultivation in cell free media, therefore these pathogens are poorly characterized on a physiological and biochemical basis. Recently the genome of ´Ca. P. mali´ and three other phytoplasmas genomes were completely sequenced. With a size of approximately 600.000 bp and 497 open reading frames the genome of `Ca. P. mali´ differs in size and organisation from the three other known phytoplasma genomes.First results indicate that both immunodominant membrane proteins and putative effector proteins of phytoplasmas are relevant in the pathogenesis of phytoplasma diseases. Therefore we will establish a yeast two hybrid (Y2H) library of membrane and effector proteins of ´Ca. P. mali´ ("Prey") to identify interactions of host-(apple-) proteins with phytoplasma proteins based on a screening with a Y2H library deriving from a cDNA library of Malus x domestica cv Golden ("Bait") .The identification of these interacting proteins will lead to a better understanding of the pathogenesis of the apple proliferation disease and moreover, enable the development of innovative management strategies. In consequence we will select aptamers via phage display which are able to disturb and/or disrupt these interactions. Moreover we will evaluate strategies for the application of these aptamers.

• DFG Programme: Research Grants