Acquisition, transmission and host range of a begomovirus associated with yellow vein mosaic disease of mesta (Hibiscus cannabinusandHibiscus sabdariffa)

Abstract

Yellow vein mosaic, a disease causing serious reductions in fibre yield of mesta (Hibiscus cannabinus and Hibiscus sabdariffa) and associated with a begomovirus, was effectively transmitted by cleft grafting and whitefly (Bemisia tabaci), but not through seed or by mechanical means. Association of the begomovirus with infected experimental host plants was determined by Southern hybridisation using a DNA A targeting probe and PCR amplification primed with specific primers. The minimum whitefly acquisition access period was 12 h and the minimum inoculation access period was 4 h. The minimum incubation period was 9 days. The whitefly transmission efficiency was 85% for H. sabdariffa and 78% for H. cannabinus. The transmissibility through cleft grafting was 80% to H. sabdariffa and 60% to H. cannabinus. The same isolate produced leaf crumpling symptoms in Vigna umbellata and Vigna unguiculata ssp. unguiculata (cowpea). The virus infection causing yellow vein mosaic symptoms on mesta was confirmed by back inoculation and molecular diagnostics. The disease incidence in fields was found to be 92.5% for H. sabdariffa and 89.5% for H. cannabinus, while under experimental conditions the incidence was of 63.7% and 37.2%, respectively.