# Virus-Specific Defense Responses in Sweetpotato: Transcriptomic Insights into Resistance and Susceptibility to SPFMV, SPCSV, and SPVD

## TL;DR

This study explores how different sweetpotato varieties respond to viral infections, identifying genes that help some plants resist viruses better than others.

## Contribution

The study provides transcriptomic insights into virus-specific immune responses in sweetpotato cultivars, identifying candidate resistance and susceptibility genes.

## Key findings

- ‘New Kawogo’ activates early and sustained immune pathways, showing robust tolerance to viral infections.
- ‘Beauregard’ exhibits weak and delayed defenses, making it more susceptible to viral diseases.
- Defense-related pathways like NBS-LRR signaling and RNA silencing are upregulated in resistant cultivars.

## Abstract

Sweetpotato is a key food crop worldwide, but its production is under threat from viral diseases, especially one called sweet potato virus disease which occurs when two different viruses infect the plant at the same time. This study examined how three types of sweetpotato plants—‘Beauregard’, ‘Tanzania’, and ‘New Kawogo’—respond to infection with each virus on its own and to the combined disease. By studying plant responses at different times after infection, the researchers discovered that ‘New Kawogo’ was able to trigger strong and lasting defenses that helped it tolerate infection, while ‘Beauregard’ showed weak and delayed defenses, making it more vulnerable. The research identified specific genes linked to either resistance or susceptibility, which can be used to guide the development of new sweetpotato varieties that are better able to withstand viral diseases. These findings are important because they provide a clear understanding of how different sweetpotato varieties naturally fight off viruses, and they open the door to breeding stronger, more resilient crops. This can help to secure sweetpotato harvests, improve food security, and support farmers who rely on this crop for their livelihoods.

Sweetpotato (Ipomoea batatas L. Lam) production is threatened by complex viral diseases, notably sweet potato virus disease (SPVD) worldwide, which results from co-infection by sweet potato feathery mottle virus (SPFMV) and sweet potato chlorotic stunt virus (SPCSV). This study provides virus-specific transcriptomic insights into the immune responses of three sweetpotato cultivars, ‘Beauregard’, ‘Tanzania’, and ‘New Kawogo’, to SPFMV, SPCSV, and SPVD. Using RNA-seq profiling across three timepoints post-infection at 3, 6, and 12 weeks, we identified distinct virus- and genotype-specific gene expression responses. ‘New Kawogo’ activated early and sustained immune pathways involving redox regulation, transcriptional control, and hormonal signaling in response to both SPCSV and SPFMV, while showing minimal transcriptional disruption under SPVD, reflecting robust tolerance. ‘Beauregard’ exhibited early suppression of immune and metabolic genes, with delayed and disorganized recovery efforts, particularly under SPVD. Defense-related pathways including NBS-LRR signaling, RNA silencing, and hormonal regulation were consistently upregulated in ‘New Kawogo’ and to a lesser extent in ‘Tanzania’, but remained inactive in ‘Beauregard’. This study highlights candidate resistance and susceptibility genes for each virus, providing a molecular basis for developing virus-resilient sweetpotato cultivars through functional genomics and marker-assisted breeding. These findings elucidate the molecular basis of virus resistance in sweetpotato and identify candidate genes for marker-assisted breeding, despite limitations arising from the use of a diploid reference genome and discrete sampling intervals.