Genome assembly and transcriptomic analysis to elucidate the ability of Nasonovia ribisnigri to break host plant resistance

Garrett, Dion; Teakle, Graham; Collier, Rosemary; Bell, James R.; Cerezo‐Medina, Sergio; Morales‐Hojas, Ramiro

Abstract

Aphid genomic resources enable the study of complex life history traits and provide information on vector biology, host adaption and speciation. The currant–lettuce aphid (Nasonovia ribisnigri (Hemiptera: Aphididae) (Mosley)) is a cosmopolitan pest of outdoor lettuce (Lactuca sativa (Asterales: Asteraceae) (Linnaeus)). Until recently, the use of resistant cultivars was an effective method for managing N. ribisnigri. A resistant cultivar containing a single gene (Nr‐locus), introduced in the 1980s, conferred complete resistance to feeding. Overreliance of this Nr‐locus in lettuce resulted in N. ribisnigri's ability to break resistance mechanism, with first reports during 2003. Our work attempts to understand which candidate gene(s) are associated with this resistance‐breaking mechanism. We present two de novo draft assembles for N. ribisnigri genomes, corresponding to both avirulent (Nr‐locus susceptible) and virulent (Nr‐locus resistant) biotypes. Changes in gene expression of the two N. ribisnigri biotypes were investigated using transcriptomic analyses of RNA‐sequencing (RNA‐seq) data to understand the potential mechanisms of resistance to the Nr‐locus in lettuce. The draft genome assemblies were 94.2% and 91.4% complete for the avirulent and virulent biotypes, respectively. Out of the 18,872 differentially expressed genes, a single gene/locus was identified in N. ribisnigri that was shared between two resistant‐breaking biotypes. This locus was further explored and validated in Real‐Time Quantitative Reverse Transcription PCR (qRT‐PCR) experiments and has predicted localisations in both the cytoplasm and nucleus. This is the first study to provide evidence that a single gene/locus is likely responsible for the ability of N. ribisnigri to overcome the Nr‐locus resistance in the lettuce host.

Citation

Garrett, D., Teakle, G., Collier, R., Bell, J. R., Cerezo‐Medina, S., & Morales‐Hojas, R. (in press). Genome assembly and transcriptomic analysis to elucidate the ability of Nasonovia ribisnigri to break host plant resistance. Insect Molecular Biology, https://doi.org/10.1111/imb.12894

• Journal Article Type: Article
• Acceptance Date: Jan 9, 2024
• Online Publication Date: Feb 13, 2024
• Deposit Date: Feb 19, 2024
• Journal: Insect Molecular Biology
• Print ISSN: 0962-1075
• Electronic ISSN: 1365-2583
• Publisher: Wiley
• Peer Reviewed: Peer Reviewed
• DOI: https://doi.org/10.1111/imb.12894
• Keywords: resistance‐breaking mechanisms, currant–lettuce aphid, insect pest, host plant resistance, gene‐for‐gene resistance
• Publisher URL: https://resjournals.onlinelibrary.wiley.com/doi/10.1111/imb.12894