First Report of Peanut stunt virus on Glycine max in Korea

Abstract

Peanut stunt virus (PSV) is a member of the genus Cucumovirus inthe family Bromoviridae. Other members of the genus are its typemember Cucumber mosaic virus (CMV) and Tomato aspermy virus(TAV). PSV like other cucumoviruses has a tripartite genome ofpositive strand RNAs, designated RNA1, RNA2 and RNA3, inother decreasing size. PSV is an economically important pathogenand occurs worldwide in legume plants. Since PSV was firstdescribed in the United States in 1966, many strains of PSV havebeen characterized. In Korea, there has been previous record on PSVinfection of peanut, black locast, red goosefoot and white clover(The Korean Society of Plant Pathology 2009)., In Sangju County ofSouth Korea in 2005, a PSV (PSV-K1) was first detected using RT-PCR from naturally infected soybean showing yellow mosaic on theleaves and virus particles were isolated from these infected leaves(Fig. 1A). Purified virus preparations were revealed the presence ofsmall isometric virions of 28 nm in diameter (Fig. 1B).The nucleotide sequence of full-length RNA3 from PSV strainK1 was determined. PSV-K1 RNA3 is 2089 nucleotides (nt)organized into two putative ORFs and 5'- and 3'-untranslatedregions (UTRs) of 52 and 229nt, respectively. Two large openreading frames (ORFs) encoded a putative movement protein (MP)(nt 53 −925) and a coat protein (CP) (nt 1183 −1860) predicted to be a31-kDa protein (P31) and a 25-kDa protein (P25), respectively.ORF3a (MP) is separated from the next ORF3b (CP) by an IR non-coding region (internal region) 257nt in length (nt 926 −1182).Multiple sequence alignments were generated using DNAMAN7.0 (Lynnon Biosoft, Quebec, Canada) on the basis of completenucleotide sequences of PSV RNA3, and a phylogenetic tree wasconstructed by the neighbor-joining algorithm (Fig. 2). Bootstrapanalysis was performed with 1,000 replicates. The resulting tree ofRNA3 revealed that PSV-K1 RNA3 is more closely related to that ofPSV-ER (94.6%) than to those of other cucumoviruses. Percentnucleotide sequence identities of RNA3 from PSV-K1 ranged from58.7 to 94.6% with RNA3 sequences of members of the genusCucumovirus. PSV was first divided into two subgroups based on awide range of comparative analyses, including serology, competi-tion hybridization and sequence comparison (Hu et al., 1997).Recently, the complete nucleotide (nt) sequence of PSV-Mi andPSV-Rp strain was determined, and based on nt sequence diversity,the establishment of a subgroup and was proposed (Yan et al., 2005and Kiss et al., 2008).Phylogenetic analyses of PSV-K1 show clearly that this strain isrelated to representatives of subgroup containing PSV-ER B. ased onthese data, we conclude that PSV is closely related to PSV-ER strainfrom cowpea and it is the first report of PSV on soybean in Korea.