Molecular Identification And Sequence Analysis Of Garlic Virus

Garlic is a common vegetable crops planting worldwide, and the asexual reproduction is the main method of garlic production. Viruses increase was caused by Long-term accumulated, which is harmful to the yield and quality of garlic. Garlic plants are often infected by various virus compound in field production and performes similar symptoms after infected , which increases the garlic prevention difficulty and the control of the virus . The Garlic virus pathogen was identified by RT-PCR, and the virus genes were cloned and analysed. The variation and evolution situation of virus DNA fragments were discussed. As a result the study provides theoretical reference to the examination, identification and harmfulness research for garlic virus, and provides research foundation to the resistance breeding for garlic virus as well.The study observed the viral particles morphology micrograph of Potyvirus, Carlavirus and Potato Virus X from garlic leaves by Colloidal gold electron microscope scanning.The coat protein gene of OYDV was amplified from garlic named"Gansuchengxianchisuan"and"Shandonglusuanwang No. 2"by RT-PCR, and the purified PCR products were cloned into T-vector for sequencing. The result showed that two OYDV DNA fragments (GSCCS and SDLSW2) were obtained. Comparison with the other twenty-two DNA fragments reported in GenBank respectively showed that the nucleotide sequence identities were 81%-98% and 81%-84%, and the amino acids sequence identities were 85%-99% and 89%-94%. The nucleotide sequence identity between GSCCS and SDLSW2 was 84%, and the amino acids identity between the two was 89%. Phylogenetic analysis showed that all the OYDV DNA fragments were classified into 3 groups. GSCCS was placed in the same clade with OYDV DNA fragment from Jinxiang of Shandong; and SDLSW2 was placed in the same clade with other 16 OYDV DNA fragments, indicating that both of the two cultivars included OYDV and there are some differences between GSCCS and SDLSW2. The degree of variation was up to 16%With the specific primers of GCLV and LYSV which were reported , using the total RNA of"Gansuchengxianchisuan"and"Shandonglusuanwang No. 2"for RT-PCR. Two DNA fragments(300bp and 520bp)were amplified by RT-PCR from the total RNA of"Shandonglusuanwang No. 2"and choned and sequenced. The sequence of GCLV from"Shandonglusuanwang No. 2"was compared with the sequence of the other 14 isolates, the result showed that the highesthomology could reach 98% of nucleic acid and 100% of amino acid. The phylogenic tree of GCLV was clustered into 3 groups.The GCLV isolate from"Gansuchengxianchisuan"was in the same group with the isolate of AB004804.1 from Japan, they represented regionally correlation. The sequence of LYSV from"Shandonglusuanwang No. 2"was compared with the sequence of the other 22 isolates, the result showed that the highesthomology could reach 97%of nucleic acid and 100% of amino acid. The phylogenic tree of LYSV was clustered into 5 groups. The LYSV isolate from"Gansuchengxianchisuan"was in the same group with the isolate of DQ925452.1 from Australia,they represented regionally correlation. The analysis shows that only the"Shandonglusuanwang No. 2"included GCLV and LYSV , indicating that there are regional characteristics with virus distribution of garlic...