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Twelve cultivars of groundnut were screened in field trials for resistance to groundnut rosette disease (GRD), caused by coinfection with Groundnut rosette assistor virus (GRAV), Groundnut rosette virus (GRV), and its satellite RNA in the coastal savannah of Ghana. ‘Oboshie’ groundnut was rated as highly resistant; ‘Bremaowuo’, ‘Nkatefufuo’, and ‘Behenase’ as resistant; and ‘Nkosuor’, ‘Kumawu’, and ‘Otuhia’ as moderately resistant. GRAV infection rates of 11.8 to 61.8% (dry season) and 13.9 to 100% (wet season) were found, which included symptomless plants, suggesting that some lacked coinfection with GRV and its satellite. Chlorotic ringspot and line-pattern symptoms were observed, suggesting infection with Groundnut ringspot virus (GRSV). Virus identity was confirmed by enzyme-linked immunosorbent assay, reverse-transcription polymerase chain reaction, and amplicon sequencing. This is the first report of GRSV in Ghana. GRSV infection rates were 0.0 to 69.5% (dry season) and 26.1 to 69.5% (wet season). Mixed infections of GRAV and GRSV were common in all cultivars except Nkosuor and Bremaowuo in the dry season. Most cultivars graft inoculated with GRD showed significantly reduced height, leaf area, chlorophyll content, dry haulm weight, and seed yield compared with healthy plants. The sources of resistance to GRD and possibly GRAV and GRSV identified in this study could be exploited in groundnut breeding programs.

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The incidence of Groundnut rosette assistor virus (GRAV) in farmers' fields and sequence diversity of groundnut rosette disease (GRD) agents were assessed in the three northern groundnut production regions of Ghana. GRAV incidence was high (69.5 to 75.0%) but not significantly different between the regions. Nucleotide sequencing of GRAV coat protein (CP) gene revealed 99-100% identity among the Ghanaian isolates and 97-100% similarity to GRAV sequences from Nigeria and Malawi for both nucleotide and predicted amino acids. Nucleotide sequence identities of partial ORF3 and 4 of Groundnut rosette virus (GRV) among the Ghanaian isolates were more variable (89-100%). Ghanaian GRV isolates were more closely related in nucleotide sequence identity to Nigerian isolates (95-98%) than Malawian isolates (88-90%). Similarly, nucleotide identity within Ghanaian GRV-sat RNA's were close (94-100%), but distinct from Nigerian (82-87%) and Malawian (82-86%) GRV-sat RNAs. Ghanaian isolates of all three agents of GRD showed no obvious isolate diversity patterns based on the regions from where they were collected. We present the first report on the distribution and genetic diversity of GRD agents in Ghana.