The effects of virus and viroid infections on the quality of fruits

Sang-Yun Cho

National Institute of Horticultural and Herbal Science, Fruit Research Division

Fruit tree virus and viroid diseases are a cause of substantial losses to the fruit industries in practically all fruit tree-growing countries. In Korea, however, relatively little data is available regarding research on the effects of these diseases on domestic fruit varieties. This study was conducted to elucidate the effects of virus and viroid infections on the fruit quality attributes of apples, pears, peaches, and grapes. To do this, we commenced trials using virus-infected, viroid-infected, combined virus/viroid-infected, and uninfected apple trees in an experimental fruit orchard at the National Institute of Horticultural and Herbal Science in 2019. In September 2021, we harvested fruits and determined selected attributes of fruit quality, including fruit yield, weight, firmness, titratable acidity, and anthocyanin content. The results revealed significant differences among virus-free trees and those infected with either virus or viroid or a combination of virus and viroid. Infection with viral and viroid diseases reduced yield (~49.3%), fruit weight (~51.9%), and anthocyanin content (~78.8%) and increased fruit firmness (~48.2%) and titratable acidity (~66%). These effects are believed to be attributable to a promotion of fruit maturation. The effects of these diseases will be monitored until 2023, and we anticipate that our findings will contribute to developing measures that can be used to prevent the introduction of fruit tree viral and viroid diseases.