Abstract:

Zucchini yellow mosaic virus was a common virus infecting wax gourd in Guangdong Province. Total RNA extraction methods of wax gourd leaves were compared，and then 76 wax gourd samples from 9 main production regions in Guangdong Province were collected and detected based onRT-PCR amplification of coat protein gene（cp）of ZYMV. The amplification products were sequenced and genetic variation analysis were carried out. The results showed that 24 samples were determined as positive with incidence ratio of 31.59%，sequence analysis revealed that full-length of ZYMV-cp of 16 isolates was 840 bp encoding a peptide with 279 amino acids. Further alignment analysis indicated that similarities of ZYMV-cp nucleotide acid and amino acid sequences ranged from 98.1% to 100% and from 96.1% to 100% respectively. The motifs of deduced amino acids sequences were conserved，all isolates contained 5 HLA sites（Human Leukocyte Antigen）and 1 N-glycosylation site expect GD121-9 with 2 additive HLA motifs. The CP protein of all isolates included conserved domain potyv_CP and DAG triple box（Asp-Ala-Gly）crucial for potyvirus transmission by aphid. Phylogenetic analysis suggested that all isolates were clustered into 7 genotypes，Guangdong isolates belonged to genotype I and contained 3 strains；All Guangdong isolates were further clustered into 3 groups with no obvious geographical differentiation. Generally ZYMV-cp in Guangdong isolates were conserved and had little molecular variation. This study determined the infection situation and genetic variation of coat protein gene of ZYMV isolates in Guangdong Province，and laid foundation for further pathogenicity research and antivirus genetic engineering.

Key words: wax gourd, Zucchini yellow mosaic virus, coat protein gene, genetic variation