Zucchini yellow mosaic virus (ZYMV) was isolated from Cucurbita pepo cv. Eskandarani
cultivated in the open field showing severe systemic symptoms. The isolated virus has wide host
range belonging to 4 families resulting systemic and local symptoms. Stability of the isolated
virus in vitro was found as 55 oC for TIP, 10-4 for DEP and LIV 4 days. The characteristic
spectrophotometric data of the highly purified virus showing that maximum and minimum
absorbance was 250 and 260 nm respectively; the ratio for A280/A260 was 1.004; and the
Amax./Amin. was 1.099 with the final yield as 0.883 mg/ml. Electron microscopy showed the
filamentous flexuous particles with about 750 X 12-15 nm. The virus was identified as ZYMV
by RT-PCR technique using high specific primers as 113 bp fragment within the nuclear
inclusion protein b (NIb) coding region of the virus genome. The cytopathological effects of
ZYMV on the infected cells were completely chloroplasts destruction, and deformation of vascular
bundles. The effect of late ZYMV infection decreased fresh weight and yield of squash plants.