A complex virome that includes two distinct emaraviruses is associated to virus-like symptoms in Camellia japonica

Abstract

SUMMARYCamellia japonica plants manifesting a complex and variable spectrum of viral symptoms like chlorotic ringspots, necrotic rings, yellowing with necrotic rings, yellow mottle, leaves and petals deformations, flower color-breaking were studied since 1940 essentially through electron microscopic analyses; however, a strong correlation between symptoms and one or more well characterized viruses was never verified. In this work samples collected from symptomatic plants were analyzed by NGS technique and a complex virome composed by viruses members of the Betaflexiviridae and Fimoviridae families was identified. In particular, the genomic fragments typical of the emaravirus group were organized in the genomes of two new emaraviruses species, tentatively named Camellia japonica associated emaravirus 1 and 2. They are the first emaraviruses described in camellia plants and were always found solely in symptomatic plants. On the contrary, in both symptomatic and asymptomatic plants, we detected five betaflexiviruses isolates that, based on aa identitiy comparisons, can be classified in two new putative species called Camellia japonica associated betaflexivirus 1 and Camellia japonica associated betaflexivirus 2. Together with other recently identified betaflexiviruses associated to Camellia japonica disease, the betaflexiviruses characterized in this study show an unusual hyper-conservation of the coat protein at aminoacidic level.