EN
Diversity of three isolates of Zucchini yellow mosaic virus (ZYMV) was analyzed by the biological and genetic characterization. Two isolates were collected from zucchini plants and one from cucumber. The symptoms induced on most hosts were different. In addition, analysis of the coat protein (CP) and nuclear inclusion protein b (Nib) of the ZYMV genome revealed high level of nucleotide variability among the isolates. Comparison of the DNA sequences of 22 isolates from different geographical regions worldwide revealed that the Polish isolates belong to different groups and they do not form a monophyletic cluster with European isolates.