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ARS Home » Pacific West Area » Wapato, Washington » Temperate Tree Fruit and Vegetable Research » Research » Publications at this Location » Publication #427562
Research Project: Integrated Approach to Manage the Pest Complex on Temperate Tree Fruits

Location: Temperate Tree Fruit and Vegetable Research

Title: Differences in ‘Candidatus Phytoplasma pruni’ gene expression when infecting sweet cherry versus leafhoppers

Author
item HARPER, SCOTT - Washington State University
item Pitino, Marco
item Walker Iii, William
item Easterling, Katherine
item Marshall, Adrian
item COWELL, SARAH - Washington State University
item HACKENBERG, LAINE - Washington State University
item Cooper, William

Submitted to: PhytoFrontiers
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/13/2025
Publication Date: 9/19/2025
Citation: Harper, S.J., Pitino, M., Walker Iii, W.B., Easterling, K.A., Marshall, A.T., Cowell, S.J., Hackenberg, L., Cooper, W.R. 2025. Differences in ‘Candidatus Phytoplasma pruni’ gene expression when infecting sweet cherry versus leafhoppers. PhytoFrontiers. https://doi.org/10.1094/PHYTOFR-06-25-0062-R.
DOI: https://doi.org/10.1094/PHYTOFR-06-25-0062-R

Interpretive Summary: X-disease causes cherry trees to develop small, unripe, and unmarketable fruit. This disease is caused by a bacterium called phytoplasma that alternates between plant and insect hosts. An incomplete understanding of the biological mechanisms for this extreme form of host switching complicates efforts to develop novel treatments that disrupt the phytoplasma life cycle and prevent tree infection. Researchers at the USDA-ARS in Wapato, WA collaborated with scientists at Washington State University to document differences in gene expression of phytoplasma infecting cherry versus insect hosts. They found that phytoplasma altered expression of 1/3 of its genes when switching between the different hosts and provide evidence for production of different proteins that allow phytoplasma to manipulate and infect the plants and insects. Researchers will use these results to better understand the processes of phytoplasma infection and to develop novel mechanisms to prevent or cure X-disease.

Technical Abstract: The X-disease phytoplasma (‘Candidatus Phytoplasma pruni’) is an obligate pathogen that is capable ofinfection, persistence, and pathogenicity in both its major plant host (Prunus spp.) and leafhopper vector(Colladonus spp.) species. How the ‘Ca. P. pruni’ interacts with its plant and insect hosts, and how it altersits gene expression to do so is unknown, therefore in this study we conducted comparative RNAseq anddifferential gene expression analysis on ‘Ca. P. pruni’ infected P. avium and C. reductus samples. We foundthat the phytoplasma altered expression of approximately 32% of its annotated protein coding andpseudogenes, including intercellular transporters, proteolytic activity, its membrane structure, as well asupregulating genes associated with potential mobile units when in insect tissues vs. in plant tissues. Mostnotably, differential expression was observed in genes that were identified by in silico analysis as beingputative secreted effectors that may play a role in allowing phytoplasma infection and survival in these twovery different host systems, as well as inducing X-disease in Prunus spp., and offers targets for control byof this damaging pathogen by disrupting phytoplasma-host interactions.Page 1 of 42Introduction