Novel viruses associated with plants of the family Amaryllidaceae in South Africa.

Nineteen samples from members of the plant genera Agapanthus, Clivia, Hippeastrum, and Scadoxus were collected from gardens in the Gauteng and Western Cape provinces of South Africa. The plants displayed highly variable symptoms of viral disease, including chlorosis, necrosis, streaking, and ringspot. RNAtag-seq was used to characterize the associated viral populations. Plants of the genus Agapanthus were found to be associated with three novel viruses from the families Caulimoviridae, Closteroviridae, and Betaflexiviridae; plants of the genus Clivia were associated with novel members of the families Potyviridae and Betaflexiviridae; and plants of the genus Scadoxus were associated with a novel member of the family Tospoviridae. Nerine latent virus was associated with plants of the genera Agapanthus, Clivia, and Hippeastrum, while hippeastrum mosaic virus was associated exclusively with a Hippeastrum cultivar.

Genetic diversity of the nucleocapsid protein gene of hippeastrum chlorotic ringspot virus from Hymenocallis littoralis in southern China.

Hymenocallis littoralis growing in southern China has been recently extensively damaged by virus-like symptoms of necrosis, chlorosis, and ringspot. Of 44 plant samples collected from Yunnan, Guangxi, Guangdong, and Fujian provinces in southern China, 32 were infected with hippeastrum chlorotic ringspot virus (HCRV). Phylogenetic analysis based on the N gene divided the virus samples into two branches suggesting a geographic distribution attributed to the initial stage of a founder effect. The N gene was under purifying selection pressure and most of the deleterious mutants had been removed. Both the population dynamics and genetic analyses suggested that populations of HCRV in southern China are spreading.

Identification of Taeniothrips eucharii (Thysanoptera: Thripidae) as a Vector of Hippeastrum chlorotic ringspot virus in Southern China.

Hippeastrum chlorotic ringspot virus (HCRV) is a putative new member of the genus Tospovirus, which was first identified infecting Hymenocallis littoralis in Yunnan Province, southwestern China. Taeniothrips eucharii, the dominant thrips species found on H. littoralis, was tested for its efficiency as a vector of the virus. We used Western blot analysis of adult thrips to detect the N protein. Transmission experiments demonstrated an average acquisition efficiency of 43.7 ± 3.4% (AAP = 24 h) for the first larval stage and a transmission efficiency of 19.1 ± 2.4% (IAP = 24 h) for adult thrips. This study reports T. eucharii as a new genus and species of thrips transmitting a Tospovirus, HCRV.