Monitoring of major viruses affecting potato early generation seeds in Rwanda. Case study: “from tissue culture to certified seeds"

Abstract

Potato is an important crop in rwanda for food security and income generation. However, its production remains low about 9t/ha compared to its potential around 50t/ha. This is due to virus infections which compromise seed quality across the early generation seeds (EGS) system. This study presents a comprehensive epidemiological assessment of six major potato viruses including Potato virus X (PVX), Potato virus Y (PVY), Potato virus M (PVM), Potato virus S (PVS), Potato virus A (PVA) and Potato leafroll virus (PLRV) throughout EGS production pathway from in vitro tissue culture to certified seeds. A total of 284 composite leaf samples were collected from in vitro tissue culture laboratories, screen houses and seed multiplication fields and were screened from viral diseases using the double antibody sandwich enzyme-linked immunosorbent assay (DAS ELISA). Results revealed that most of tissue culture derived plantlets were free from viruses, PVX (10%) and of PVY (1.67%) were detected, suggesting contamination during in vitro multiplication. In screen houses, PVY (p < 0.0001) and PVX (41.1%) were significantly prevalent, highlighting vector transmission and mechanical spread risks. Seed multiplication fields showed high incidences of PVY (p=0.0002) and PLRV (p=0.042) signaling virus accumulation and inadequate vector control. Varietal susceptibility was evident with Kinigi, Gikungu and Kirundo being particularly affected. The findings underscore systemic gaps in Rwanda’s potato system where operational lapses, varietal susceptibility and region disparities amplify viral pressure. Based on these findings, this study recommends to enhance aseptic conditions in potato tissue culture facility and envisage to implement virus clean up protocols for high-value potato varieties like Kinigi and establishing mandatory virus testing at critical stages of EGS value chain to ensure phytosanitary integrity.