Sequencing Of Maize Dwarf Mosaic Disease Sample Collect From HeNan Province

Maize dwarf mosaic disease is one of major problems in corn growing area all over the world. The disease can cause great economic damage in some areas. The causal agent of the disease belongs to Potyvirus, but which kind of specie it should belong to remains unknown till now.The coding region in the genomic RNA of the Maize Dwarf Mosaic Virus (MDMV) was gained by the way of reverse transcription polymerase chain reaction (RT-PCR). 5'-non-translated region (NTR) was obtained by rapid amplication of cDNA end (RACE). The amplificted fragments were transformed into JM109 competent cell and sequenced by ABI PRISM 377 DNA Sequencer. The genomic sequence was finally acquired by linking the adjacent segments and analysed using DNASTAR program. The GenBank accession number for the sequence in this paper reported is AF494510.The complete viral genomic RNA of MDMV-HN is composed of 9596 nucleotides, excluding the poly (A) tail. In this genome, a large single open reading frame (ORF) of 9192 nucleotides was predicted which encoded a polyprotein of 3063 amino acids. The 5' NTR of MDMV-HN proceeding the ORF is 149 nucleotides and 3'NTR is 255 nucleotides (excluding the poly (A) tail). The putative cleavage sites in the polyprotein is Y/A, G/G, E/G, Q/S, Q/G, Q/G, E/S, Q/C and Q/S in turn.The complete sequence of MDMV-HN and SCMV-HZ isolate shares identities of 94.2% and 98.3% at the nucleotide and amino acid levels, respectively. There is 99.3% nucleotide identity over the 3'NTR region. The amino acid similarities are more than 96% among putative gene products ,even 100% in some region(6KK 6K2> VPG).According to the criterion of the 7th ICTV meeting, they maybe belong to the same strain.Sequence comparison of the coat proteins show that MDMV-HN shares identities of 94.3% with SCMV-GD isolate at the amino acid levels and the polyprotein is 91.5% between them, which suggests that they should belong to different strains.MDMV-HN shares 90.7%?0.9% homology with those isolated from sugarcane in China at the amino acid levels.They should belong to the same viru species.From putative cleavage sites alignments, it was found that MDMV-HN has large different with JGMV and SrMV. So they belong to different virus. The identity of coat protein between MDMV-HN and MDMV-Bg is 70.4% and that of the whole genomic RNA is 69.1%, which suggests that they should belong to different viru species.