# Key Sweet Potato Viruses in Fujian Province and Their Distribution, Harmfulness, and Implications in China

## TL;DR

This study identifies and analyzes key sweet potato viruses in Fujian, China, highlighting their distribution and impact on crop yield.

## Contribution

The study reveals the prevalence and harmful effects of multiple sweet potato viruses in Fujian, including their co-infection patterns and regional distribution.

## Key findings

- Quanzhou, Fuzhou, and Putian had the highest virus diversity with 10, 9, and 7 viruses detected, respectively.
- Compound infestations were common, with up to 6 viruses infecting different sweet potato varieties.
- SPCSV co-infection with SPFMV led to SPVD, with RNase3 expression correlated to disease severity.

## Abstract

China, the largest global producer of sweet potatoes, faces significant threats from viral diseases, particularly in Fujian Province, where sweet potatoes are the second most important food crop after rice. This study identified 11 viruses, including sweet potato feathery mottle virus (SPFMV) and sweet potato chlorotic stunt virus (SPCSV), infecting sweet potatoes in Fujian. Sequence comparisons revealed diverse strains from various sources. Virus prevalence varied across regions, with Quanzhou, Fuzhou, and Putian severely affected, detecting 10, 9, and 7 viruses, respectively, compared to only 3 in Sanming and Longyan. In particular, sweet potato virus disease (SPVD) caused the most severe damage during the seeding stages, resulting in dwarfing and leaf deformation, while the damage was lighter during the growth period, manifesting as the yellowing and brittleness of the leaves, ultimately reducing the yield. Compound infestations predominated, with between 0 and 6 viruses infecting different sweet potato varieties. Single-virus infections were observed for sweet potato virus 2 (SPV2), sweet potato symptomless virus 1 (SPSMV-1), and sweet potato pakakuy virus (SPPV), while others, particularly SPCSV, were frequently co-infected with SPFMV, leading to SPVD development. Further analysis showed that the RNase3 expression of SPCSV was correlated with the SPVD severity in sweet potato. These findings provide insights into the epidemiology of sweet potato viruses and serve as a reference for developing targeted disease management strategies.