Natural Satsuma Dwarf Virus Infection of Two Woody Plants, Daphniphyllum teijsmannii Zoll. ex Kurz. and Viburnum odoratissimum Ker-Gaul. var. awabuki (K. Koch) Zabel near Citrus Fields

In Japan, the production of Satsuma mandarin (Citrus unshiu Marc.) is seriously affected by Satsuma dwarf virus (SDV). This study provides evidence of the natural SDV infection of two woody plants, Daphniphyllum teijsmannii and Viburnum odoratissimum var. awabuki, which are common in the warm temperate forests of Japan. Forty-four species of wild woody plants that grew near several SDV-infested fields were surveyed for the presence of SDV using immunochromatography assay (ICA). Five D. teijsmannii trees and four trees of V. odoratissimum var. awabuki tested positive for SDV. Trees of D. teijsmannii and V. odoratissimum var. awabuki that grew far from the citrus fields tested negative for SDV, suggesting that these species are hosts but not the main natural reservoirs of SDV. Comparisons of the partial nucleotide sequences of the larger coat protein gene showed that SDV isolates from closely-grown trees of citrus, D. teijsmannii, and V. odoratissimum var. awabuki were genetically very homogeneous. The results suggested that the natural transmission of SDV occurred among trees of citrus, D. teijsmannii, and V. odoratissimum var. awabuki.