[show abstract][hide abstract] ABSTRACT: The complete genome sequence of Zucchini yellow mosaic virus stain A (ZYMV-A) isolated from a hollyhock (Althaea rosea) was determined by using RT-PCR with a series of primer sets. The virus genome consisted of 9593 nucleotides (nt), excluding the poly(A) tract at 3' terminus of the virus genome, with 5' and 3' untrans-lated region of 139 and 211 nt, respectively. The deduced polyprotein of ZYMV-A consisted of 3080 amino acid (aa) residues and was 351 kDa in molecular weight. All proteolytic cleavage sites of the polyprotein of ZYMV-A were compared with those of ZYMV strains, which showed the cleavage sites were conserved among ZYMV strains. The HC-Pro contained the KITC and PTK motifs, and the DAG motif was located at CP ORF of ZYMV-A, suggesting that ZYMV-A is aphid-transmissible. Phylogenetic tree analysis based on the complete genome among ZYMV strains or CP ORFs with other potyviruses showed ZYMV strains formed a distinct group. These results clearly confirmed that ZYMV-A was another distinct strain in ZYMV population at molecular level. The genus Potyvirus is the largest group of plant viruses and consists of over 200 definite and tentative species of viruses (Reichmann et al., 1992; van Regenmortel et al., 2000). Potyviruses cause severe damage to various crops in the aspect of quantity and quality. In cucurbit crops, Zucchini yellow mosaic virus (ZYMV), Watermelon mosaic virus and Papaya ringsopt virus, belonging to potyvirus genus, have severely caused the economical damage all over the world (Hull, 2002). In particular, ZYMV, one of the most damaging viruses worldwide causes very severe mosaic symptoms on leaf and its distortion and mal-formation of fruit (Desbiez et al., 2002; Lecoq and Pitrat 1984; Lisa et al., 1981; Provvidenti et al., 1984). In Korea, the disease caused by ZYMV has been considered one of major limiting factors for the production of cucurbits (Kwon et al., 2005; Yoon and Choi, 1998). ZYMV as well as other species of potyviruses is transmitted by aphids in a non-persistent manner, and the virus can be seed-transmitted (Gal-on et al., 1992; Lisa and Lecoq, 1984; Yoon, 1999; Yoon and Choi, 1998). Like potyviruses, ZYMV particles are flexuous rods, 750 nm long, and contain a monopartite genome consisting of a positive-sense ssRNA with a 5' genome-linked protein and a 3' poly(A) tract (Hull, 2002; Siaw et al., 1985; van Regenmortel et al., 2000). The entire genomes for several ZYMV strains, including three Korean strains, have been reported (Baker et al. Zhao et al., 2003). A lot of sequence information for 3' terminus of the genome or partial virus-open reading frame (ORF) has been also available from various strains of ZYMV (Lecoq and Purcifull, 1992; Lee and Wong, 1998; Quemada et al., 1990). Notably, all ZYMV strains isolated from cultivated cucurbit plants have been used for determination of the complete genome sequence or partial genomic information. We previously identified and characterized the biological properties of ZYMV strain A (ZYMV-A) isolated from a hollyhock (Althaea rosea) showing yellowing and mosaic symptoms in 2002, Korea (Choi et al., 2002b). The pheno-type of ZYMV-A was slightly different from pathological phenotypes of common strains of ZYMV on host plants. This strain also could facilitate systemic movement of a strain of movement-deficient Cucumber mosaic virus in zucchini squash (Choi et al., 2002a). As next step, we sequenced further the complete genome of ZYMV-A and compared its sequence with those of other ZYMV strains and different potyviruses reported in Gen-Bank. To the best of our knowledge, this report represents the first determination of genome sequence of ZYMV that was originated from a weed other than cucurbits.