3′ UTR is critical for viral RNA accumulation of jasmine virus H

Abstract

Jasmine virus H (JaVH) is a newly reported viral pathogen of jasmine in China and USA. To study the viral gene function and pathogenic mechanism, a full-length infectious clone of JaVH (pXT-JaVHFJ) was constructed under the control of the cauliflower mosaic virus 35S promoter. pXT-JaVHFJ induced a systemic infection in Nicotiana benthamiana plants by Agro-infiltration, which demonstrated that pXT-JaVHFJ was biologically active. Jasmine showed yellow spots after rubbing with total RNA extracted from Agro-infiltrated N. benthamiana, indicating that JaVH was highly associated with yellow mosaic symptoms observed on jasmine. To investigate the occurrence and mutations of the virus, jasmine samples were collected from eight provinces of China and were tested for JaVH. The samples that were tested positive for JaVH were used to determine the complete genome sequences. They were comprised of 3867 or 3868 nucleotides and their genome organizations resembled that we previous reported for JaVH-FJ. Phylogenetic analyses and sequence comparisons suggest that the eight virus isolates were close isolates of JaVH-FJ and the isolate from Jilin Province was most closely related to JaVH-FJ with 99.2% nucleotide identity over the entire genome and 99.7% identity of coat protein. Further comparative analyses of JaVH-FJ and JaVH-JL revealed additional nucleotide differences in the 3′-untranslated region (3′ UTR). An infectious clone of JaVH-JL and chimeric mutants containing JaVH-FJ or JaVH-JL 3′ UTRs were then constructed for further study. The differential accumulation of JaVH with distinct 3′ UTR suggested that the 3′ UTR of JaVH plays a crucial role in viral RNA accumulation.