Differential gene expression of Asian citrus psyllids infected with ' Ca. Liberibacter asiaticus' reveals hyper-susceptibility to invasion by instar fourth-fifth and teneral adult stages

Ruifeng He; Tonja W Fisher; Surya Saha; Kirsten Peiz-Stelinski; Mark A Willis; David R Gang; Judith K Brown

doi:10.3389/fpls.2023.1229620

Differential gene expression of Asian citrus psyllids infected with ' Ca. Liberibacter asiaticus' reveals hyper-susceptibility to invasion by instar fourth-fifth and teneral adult stages

Front Plant Sci. 2023 Aug 17:14:1229620. doi: 10.3389/fpls.2023.1229620. eCollection 2023.

Authors

Ruifeng He^{1

2}, Tonja W Fisher³, Surya Saha^{4

5}, Kirsten Peiz-Stelinski⁶, Mark A Willis¹, David R Gang¹, Judith K Brown³

Affiliations

¹ Institute of Biological Chemistry, Washington State University, Pullman, WA, United States.
² Soybean Genomics and Improvement Laboratory, US Department of Agriculture (USDA)-Agricultural Research Service (ARS), Beltsville, MD, United States.
³ School of Plant Sciences, University of Arizona, Tucson, AZ, United States.
⁴ Sol Genomics Network, Boyce Thompson Institute, Ithaca, NY, United States.
⁵ School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, AZ, United States.
⁶ Citrus Research and Education Center, Department of Entomology and Nematology, University of Florida, Lake Alfred, FL, United States.

Abstract

The bacterial pathogen Candidatus Liberibacter asiaticus (CLas) is the causal agent of citrus greening disease. This unusual plant pathogenic bacterium also infects its psyllid host, the Asian citrus psyllid (ACP). To investigate gene expression profiles with a focus on genes involved in infection and circulation within the psyllid host of CLas, RNA-seq libraries were constructed from CLas-infected and CLas-free ACP representing the five different developmental stages, namely, nymphal instars 1-2, 3, and 4-5, and teneral and mature adults. The Gbp paired-end reads (296) representing the transcriptional landscape of ACP across all life stages and the official gene set (OGSv3) were annotated based on the chromosomal-length v3 reference genome and used for de novo transcript discovery resulting in 25,410 genes with 124,177 isoforms. Differential expression analysis across all ACP developmental stages revealed instar-specific responses to CLas infection, with greater overall responses by nymphal instars, compared to mature adults. More genes were over-or under-expressed in the 4-5^th nymphal instars and young (teneral) adults than in instars 1-3, or mature adults, indicating that late immature instars and young maturing adults were highly responsive to CLas infection. Genes identified with potential for direct or indirect involvement in the ACP-CLas circulative, propagative transmission pathway were predominantly responsive during early invasion and infection processes and included canonical cytoskeletal remodeling and endo-exocytosis pathway genes. Genes with predicted functions in defense, development, and immunity exhibited the greatest responsiveness to CLas infection. These results shed new light on ACP-CLas interactions essential for pathogenesis of the psyllid host, some that share striking similarities with effector protein-animal host mechanisms reported for other culturable and/or fastidious bacterial- or viral- host pathosystems.

Keywords: Diaphorina citri; RNA-seq analysis; circulative; host-pathogen interactions; propagative transmission; psyllidae.

Grants and funding

The authors declare that this study received funding from the Florida Citrus Res. & Dev. Foundation: Citrus psyllid transcriptome and time course differential expression in whole psyllids and psyllid organs. 2010- 2013. Grant #21; and the USDA-NIFA SRCRI. NuPsyllid-Rear and release psyllids as biocontrol for HLB. 2013-2017. Subcontract: Citrus Research and Development Foundation, Inc. 13-005NU-784. The funders were not involved in the study design, collection, analysis, interpretation of data, the writing of this article or the decision to submit it for publication.