| Barley yellow dwarf viruses (BYDVs) are one of the major virus for China's wheat virus diseases.They can cause significant economic losses worldwide because of damage to barley,wheat,and oats.Because of the different geogaraphy sources,the variability of BYDVs may exist.The main objective of the experiments was to identify the molecular variability,strain type and phylogenetic relationship of different BYDVs ORF5 genes using the materials of Chinese wheat isolates which were infected by virus.Nine hundreds and eighty-seven wheat samples showing barley yellow diseases were collected from different regions in China.Reverse transcription polymerase chain reaction (RT-PCR) and nucleic acid spot hybridization (NASH) were made using the RNA of samples to detect the ORF5 gene. The results showed that 42 percent samples had positive reaction which indicate special fragements and positive spots and BYDV-GAV hold the more large proportion and BYDV-PAV,BYDV-GPV showed predominance in specific regions.BYDV-PAV mainly occur in Wuhan,Hubei Province,Jinan, Shandong Province,Hefei Province,Anhui Province,Nanjing,Jiangsu Province,Zhengzhou,Henan Province, Lanzhou and Gangu,regions.GPV,existed as particular strain in China,had less infection and appears in Yuncheng,Linfen,Shanxi Province,Hancheng, Shanxi Province, Nanjing, Jiangsu Province,Kunming,Yunnan Province,Lanzhou and Gangu,Gansu Province mostly.The product of RT-PCR were cloned and sequenced of ORF5 gene for encoding read through protein,through the mulriple sequences alignments analysised different virus (strains) of the molecular variation.Comparison of 45 nucletide sequences of BYDV-GAV revealed high conservation of the ORF5 gene.Phylogenetic tree constructed based on the sequences of GAV ORF5 genes from China with several parallel branches showed that there was no obvious clustering,but formed it three branches (â… ,â…¡,â…¢).Most isolate gather in brancheâ… ,and the genetic distance between them are more similar.The homology high with the published Chinese isolate.In groupâ…¡contains Henan,Yunnan,Guizhou and Tibet.Groupâ…¢only contains two new isolates, they published the Chinese isolate BYDV-GAV-CN homology with the lowest affinity farthest.Compared with BYDV-GAV-CN,BYDV-PAV was another case,many substitutions in 1335-1350bp implied high variality,especially 3'terminal sequence.The phylogenetic tree constructed based on the sequences of BYDV-PAV ORF5 genes from China formed four branches (â… toâ…£).Although these groups were all from the same branch,the variability of sequences of three groups is obvious,which resulted in the diversity clusterings.Groupâ… ,â…¡have a common ancestor,groupâ…¢,â…£have a common ancestor. Groupâ… included 39 new isolates,1 China published isolate.Groupâ…¡mainly is Yunnan isolates,they are closer with the published BYDV-PAV-CN isolate.Groupâ…¢,including a newly isolated from Henan and six foreign isolates.â…£groups abroad have been published by the two isolates formed. But the 09HNZZ4 isolat with foreign isolates is close relationship with high similarity,while isolates with domestic distant relationship,similar to low. And the Henan isolate where in the three groups are distributed,and not concentrated in one single group,the description shows that Henan PAV rich in diversity.Throughout the BYDV-PAV isolate groups,these isolates did not have the same collection time and collection place and are strictly limited.BYDV-GPV-ORF5 gene mutation are similar with BYDV-GPV-RTP-ORF5.and the degree of identity among sequences is high, changes clustered in the 3'end. |
