Investigation Of Two Citrus Virus Diseases And The Genetic Diversity Of The Pathogens In Guangxi

The occurrences of citrus tatter leaf disease and citrus leaf spot disease were investigated in the main planting areas of citrus in Nanning,Chongzuo,Liuzhou,Guilin,Yulin,Hechi,Hezhou,and Fangchenggang of Guangxi.Their pathogenic viruses were detected using RT-PCR,viral genome sequencing,and genetic diversity analysis,including Citrus tatter leaf virus(CTLV),Apple Stem Grooving Virus(ASGV),and Citrus leaf blotch virus(CLBV).The results showed that the detection rates of CTLV,ASGV,and CLBV in suspected virus samples collected from citrus-producing areas in Nanning,Guilin,and Yulin were 22.3%,35.7%,and 7.6%,respectively.Additionally,the mixed infection of multiple viruses was detected.The genetic diversity analysis of the CP gene sequence of the isolates revealed that ASGV and CTLV had no significant host and location.Moreover,all the strains of CLBV showed a distinct relationship with the host.In this study,three full-length sequences of three isolates were identified,deposited to NCBI.The genomic sequence and the coding gene sequences of the movement protein(MP)and the coat protein(CP)of our isolated ASGV-ZG-2 strains had homologies with the reference sequence recorded in the NCBI database,which ranged from 79.0 %-91.0%,81.8%-93.0%,88.9%-93.1%,respectively.It is the first isolated ASGV genome sequence from Wogan in Guangxi,China.Analysis of its near-full-length genomic sequence,MP gene,and CP gene shows the regularity of geographical distribution,without host specificity.The recombination analysis showed that the isolated ZG-2 was a recombination virus,and eight groups of effective recombination events were detected in 15 isolates.This study,for the first time,reports theoccurrence of citrus tatter leaf disease and citrus leaf spot disease in Guangxi and the genetic diversity of their pathogenic viruses,providing a reference for the diagnosis and control of citrus virus diseases.