Lasting consequences of psyllid (Bactericera cockerelli L.) infestation on tomato plant gene expression.

Authors: HARRISON, KYLE; MENDOZA-HERRERA, AZUCENA - TEXAS A&M UNIVERSITY; LEVY, JULIEN - TEXAS A&M UNIVERSITY; TAMBORINDEGUY, CECILIA - TEXAS A&M UNIVERSITY

Submitted to: BMC Plant Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/4/2021
Publication Date: 2/24/2021
Citation: Harrison, K.E., Mendoza-Herrera, A., Levy, J., Tamborindeguy, C. 2021. Lasting consequences of psyllid (Bactericera cockerelli L.) infestation on tomato plant gene expression.. Biomed Central (BMC) Plant Biology. 21:114. https://doi.org/10.1186/s12870-021-02876-z.
DOI: https://doi.org/10.1186/s12870-021-02876-z

Interpretive Summary: The tomato psyllid, Bactericera cockerelli, is a tomato pest in the U.S. and vectors a disease-causing pathogen. Currently, the most effective method for controlling these diseases involves insecticide application to manage the psyllid vector. However, this strategy is unsustainable and will eventually lead to insecticide resistance evolving among psyllid populations. New strategies must be developed that incorporate a plant's natural defense responses. To better characterize the plant defense response of tomato plants to psyllid infestation, gene expression changes were characterized in plants that had previously been exposed to psyllids and compared to uninfested plants. The authors found 362 differentially expressed genes (DEGs) in psyllid-infested tomato plants. These genes were related to plant response to abiotic/biotic stress, transcription/translation, cellular signaling/transport, and photosynthesis. Gene expression changes are predicted to result in increased plant responsiveness to stress and impaired photosynthesis and growth. These results were supported by plant growth experiments and psyllid development experiments which showed that tomato plant growth stunted after psyllid infestation and that psyllid survival was impaired when grown on tomato plants previously exposed to psyllids. These results suggested that psyllid infestation has lasting consequences for tomato defense and health.

Technical Abstract: The tomato psyllid, Bactericera cockerelli Šulc (Hemiptera: Triozidae), is a pest of solanaceous crops such as tomato (Solanum lycopersicum L.) in the U.S. and vectors the disease-causing pathogen ‘Candidatus Liberibacter solanacearum’. Currently, the only effective strategies for controlling the diseases associated with this pathogen involve regular pesticide applications to manage psyllid population density. However, such practices are unsustainable and will eventually lead to widespread pesticide resistance in psyllids. Therefore, new control strategies must be developed to increase host-plant resistance to insect vectors. For example, expression of constitutive and inducible plant defenses can be improved through selection. Currently, it is still unknown whether psyllid infestation has any lasting consequences on tomato plant defense or tomato plant gene expression in general. In order to characterize the genes putatively involved in tomato defense against psyllid infestation, RNA was extracted from psyllid-infested and uninfested tomato leaves (Moneymaker) three weeks post-infestation. Transcriptome analysis identified 362 differentially expressed genes. These differentially expressed genes were primarily associated with defense responses to abiotic/biotic stress, transcription/translation, cellular signaling/transport, and photosynthesis. These gene expression changes suggested that tomato plants underwent a reduction in plant growth/health in exchange for improved defense against stress that was observable three weeks after psyllid infestation. Consistent with these observations, tomato plant growth experiments determined that the plants were shorter three weeks after psyllid infestation. Furthermore, psyllid nymphs had lower survival rates on tomato plants that had been previously psyllid infested. These results suggested that psyllid infestation has lasting consequences for tomato gene expression, defense, and growth.