Genome assemblies and annotations of Nasonovia ribisnigri to study the resistant-breaking mechanisms in host plant resistant biotypes. Nasonovia_ribisnigri

Genomic resources for aphids enable the study of complex life history traits and provide information on vector biology, host adaption and speciation. Only a comparatively small number of aphid genomic resources have so far been generated, despite their large economic impact. The currant-lettuce aphid (Nasonovia ribisnigri, Mosley) is a major pest of outdoor lettuce crops (Lactuca sativa L.) in several parts of the world. The use of resistant cultivars is an effective method for managing pest insects and are regularly incorporated into integrated pest management programmes. A N. ribisnigri resistant lettuce cultivar was introduced into the outdoor lettuce industry in the 1980’s that contained a single gene (Nr-gene), preventing N. ribisnigri successfully feeding. This single gene resistance was used throughout the 1980’s until ~2003, when the first reports of N. ribisnigri were able to break resistance and feed on these resistant cultivars. Here, we present two de novo draft assembles for N. ribisnigri genomes, corresponding to both a susceptible and resistance-breaking biotype. Changes in gene expression of the two N. ribisnigri biotypes were investigated using transcriptomic analyses of RNA-seq data to study the potential mechanisms of resistance to the Nr-gene in lettuce. The draft genome assemblies were 94.2% and 91.4% complete for the susceptible and resistance-breaking biotypes, respectively. Out of the 18,872 differentially expressed genes, one gene was shared between both resistance-breaking biotypes (gene_2698). This is the first study to provide strong evidence that a single gene is responsible for the ability of N. ribisnigri to overcome the Nr-gene resistance in lettuce.