Does the causative agent of Syndrome Basses Richesses (SBR), Candidatus Arsenophonus phytopathogenicus, alter sugar beet phloem composition or plant-emitted volatiles?

The so-called "Syndrome Basses Richesses" (SBR) is a bacterial disease of the sugar beet plant, which can lead to a reduced sugar content in the beet and thus to significant yield losses. The causative agent of the SBR is the γ-proteobacterium Candidatus Arsenophonus phytopathogenicus, which is transmitted by the sucking activity of the planthopper Pentastiridius leporinus (Hemiptera: Cixiidae). Direct control of the pathogen and its vector is not yet possible, and up to now there are no resistant beet varieties available. A critical barrier to SBR containment and control is insufficient knowledge of the multitrophic interactions in the plant-insect vector-Arsenophonus system. One aim of the joint research project PENTA-Resist funded by the Federal Ministry of Food and Agriculture (BMEL) in Germany, is therefore the elucidation of the host finding and host acceptance behavior of the planthopper and the characterization of the possible mutualistic symbiosis between bacteria and insect. The present study checks the hypothesis whether P. leporinus benefits from sugar beet infection with Ca. Arsenophonus phytopathogenicus, since the pathogen affects beet physiology. Therefore, sugar beet phloem sap and volatile profiles of healthy and infected plants were analyzed.