The diseased sample G7 was collected from Ageratum plants showing yellow vein symptoms in Xialian,Nanning,Guangxi province and tested with primers specific for DNA-A of several geminiviruses by polymerase chain reaction.The results showed that mixed infection of begomoviruses appeared in G7 sample.Partial DNA-A sequence comparison with other geminiviruses showed that G7 sample was infected by 5 dif-ferent begomoviruses,they were Papaya leaf curl China virus(PaLCuCNV),Ageratum yellow vein China virus(AYVCNV),Tomato leaf curl China virus(ToLCCNV),Euphorbia leaf curl virus(EuLCV) and Tobacco leaf curl Yunnan virus(TbLCYNV).
The molecular variation of satellite DNA associated with Tobacco curly shoot virus (TbCSV) was compared by DNA sequencing of progenies of TbCSV DNA in Nicotiana benthamiana and N. glutinosa plants agroinoculated with infectious clones of TbCSV and its associated DNA. Comparisons indicated that TbCSV DNA populations had the higher levels of mutation frequency in N. glutinosa than that in N. benthamiana, and mutations generated in N. benthamiana were found upstream or downstream of C1 ORF whereas those in N. glutinosa were mostly located in A-rich region. No mutation was found in C1 ORF and satellite conserved region of DNA. The biological significance of the mutation accumulation and its role in disease epidemic were discussed.
