Biological characteristics and nucleotide sequences of three Korean isolates of Zucchini yellow mosaic virus

Abstract

Zucchini yellow mosaic virus (ZYMV) is one of the most economically important viruses of cucurbit crops, causing severe mosaic, necrosis, and malformation. Three ZYMV isolates were obtained from pumpkins at Andong (ZYMV-PA), Euiryung (ZYMV-PE), and Suwon (ZYMV-PS), and their biological variability was determined on different hosts, including cucurbit crops as well as other indicator plants. ZYMV-PA caused the most severe symptoms, including severe mosaic, size reduction, and deformation, in oriental melon (Cucumis melo) and cucumber (Cucumis sativus) leaves. In contrast, ZYMV-PE and ZYMV-PS caused mild mosaic symptoms on oriental melon and cucumber. The nucleotide sequences of the genomic RNAs were determined and compared to the sequences of other potyviruses, including ZYMV isolates Reunion Island and TW-TN3. Each ZYMV Isolate had a genome of 9593 nucleotides, excluding the poly(A) tail, and contained 139 and 214 nucleotides in the 5′- and 3′-untranslated regions, respectively. Each had one large open reading frame encoding a protein of about 351 kDa. The nucleotide sequences of ZYMV-PA, ZYMV-PE, and ZYMV-PS were more than 96.0% and the deduced amino acid sequences were more than 98.1% identical. When compared with other ZYMV isolates in a phylogenetic analysis, these three viruses formed a distinct virus clade and were more distantly related to other potyviruses (43.5%–62.8% identity).