Molecular diversity of main cucurbit viruses in Syria

Abstract

Cucurbits are among the main crops and vegetables grown in Syria, including cucumber (Cucumis sativus), melon (C. melo), watermelon (Citrullus lanatus), and various squash species (Cucurbita pepo, C. moschata, and C. maxima). Cucurbit virus diseases are responsible for significant yield and quality losses to cucurbit crops. In the current study, we investigated the etiology of cucurbit virus diseases, and assessed the molecular diversity of the causal viruses in three major regions of cucurbit production of Syria. Out of 12 viruses and virus groups investigated, zucchini yellow mosaic virus (ZYMV), watermelon mosaic virus (WMV),cucumber mosaic virus (CMV), cucurbit aphid-borne yellows virus (CABYV) and a new member of the genus Polerovirus, pepo aphid-borne yellows virus (PABYV) were detected in various cucurbit crops from plants displaying virus-like symptoms. Syrian ZYMV isolates were closely related and shared low diversity suggesting a relatively recent introduction. A diverse population of WMV with four classical and two emerging isolates of WMV were identified, which complicates the control program. Two CMV isolates were closely related to CMV isolates, reported previously from other crops in the same regions, which may indicate frequent movements of CMV among different hosts. The finding of an isolate of PABYV, a newly described species of the genus Polerovirus, reveals a wider distribution of this virus that may represent a potential emerging problem to cucurbit production.