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Sugarcane yellow leaf virus (SCYLV) (genus Polerovirus,family Luteoviridae),the causal agent of sug arcane yellow leaf disease (YLD),was first detectedin China in 2006.To assess the distribution of SCYLV in the major sugarcane-growing Chinese provinces,leaf samples from 22 sugarcane clones (Saccharum spp.hybrid) showing YLD symptoms were collected and analyzed for infection by the virus using reverse transcription PCR (RT-PCR),quantita tive RT-PCR,and immunological assays.A complete genomic sequence (5,879 nt) of the Chinese SCYLV isolate CHN-FJl and partial genomic sequences (2,915 nt) of 13 other Chinese SCYLV isolates from this study were ampli fied,cloned,and sequenced.The genomic sequence of the CHN-FJl isolate was found to share a high identity (98.4-99.1 0-10) with those of the Brazilian (BRA) genotype isolates and a low identity (86.5-86.9 0-10) with those of the CHNl and Cuban (CUB) genotype isolates.The genetic diversity of these 14 Chinese SCYLV isolates was assessed along with that of 29 SCYLV isolates of worldwide origin reported in the GenBank database,based on the full or partial genomic sequence.Phylogenetic analysis demonstrated that all the 14 Chinese SCYLV isolates clustered into one large group with the BRA genotype and 12 0ther reported SCYLV isolates.In addition,five reported Chinese SCYLV isolates were grouped with the Peruvian (PER),CHNl and CUB genotypes.We therefore speculated that at least four SCYLV genotypes,BRA,PER,CHNI,and CUB,are associated with YLD in China.Interestingly,a 39-nt deletion was detected in the sequence of the CHN-GD3 isolate,in the middle of the ORFl region adjacent to the overlap between ORFl and ORF2.This location is known to be one of the recombination breakpoints in the Luteoviridae family.