Characterization and variation of zucchini yellow mosaic virus isolated from pumpkins in Korea

Abstract

Zucchini yellow mosaic virus (ZYMV), a member of the Genus Potyvirus, is one of the most economically important viruses of cucurbit crops. Biological variability has been observed among ZYMV isolates, concerning host range, symptomatology and aphid transmissibility. We obtained three ZYMV isolates from pumpkins at Andong (ZYMV-PA), Euiryung (ZYMV-PE), and Suwon (ZYMV-PS), respectively. In order to determine biological variability of each ZYMV isolate, these isolates were inoculated to the different host plants including cucurbit and some indicator plants. Each ZYMV isolate displayed distinctive symptoms on cucurbit plants as well as indicator plants. Symptoms induced by ZYMV isolates in watermelon, leaves in watermelon; ZYMV-PA isolate developed a yellow mosaic, leaves of ZYMV-PE isolate developed a yellow mosaic and became blistered and those of ZYMV-PS isolate developed a yellow mosaic and blistered. In cucumber, leaves of ZYMV-PA leaves became severely blistered and malformed, leaves of ZYM-PE developed vein banding and leaves of ZYMV-PS developed a yellow mosaic and became severely blistered, malformed. In oriental melon, leaves of ZYMV-PA inoculated plants developed yellowing and became severly blistered and malformed, leaves of ZYMV-PE developed yellowing, vein banding and became dwarfed and leaves of ZYMV-PS developed yellowing, vein banding and became malformed. Only ZYMV-PS did not infected with Gomphrena globosa, indicator plant. Sequence of the genomic RNA of each isolate was also determined by reverse transcriptionpolymerase chain reaction (RT-PCR) using specific oligonucleotide primers and by the 5'' and 3'' RACE. The genomic RNA was 9.5 kb in length and contained one open reading frame encoding 350 kDa protein that is proteolytically cleaved by self-encoded proteases into functional proteins. The base composition of three isolates, PA was 31.34% adenine, 23.59% guanine, 19.19% cytosine, 25.88% uracil, PE isolate was 31.53% adenine, 23.59% guanine, 19.10% cytosine, 25.79% uracil, PS isolate was 31.56% adenine, 23.57% guanine, 19.11% cytosine, 25.76% uracil.