Cucurbit chlorotic yellows virus: Insights Into Its Natural Host Range, Genetic Variability, and Transmission Parameters.

Cucurbit chlorotic yellows virus (CCYV) (genus Crinivirus, family Closteroviridae) is implicated in cucurbit yellows disease (CYV), causing typical interveinal yellowing symptoms in leaves, and is transmitted by Bemisia tabaci Mediterranean (MED) and Middle East-Asia Minor 1 (MEAM1). Due to its recent report in cucurbit crops in Greece, field surveys were conducted during 2011-2016 to determine the presence of the virus in symptomatic cucurbits and alternative hosts among arable weed species. Results indicated the restricted spread of the virus and identified 13 weed species as CCYV hosts for the first time. Sequence analysis of the RNA-dependent RNA polymerase (RNA1) coat and minor coat proteins (RNA2) revealed very low genetic diversity (<0.1%) among the Greek isolates. Transmission experiments were also conducted using B. tabaci MED with retention determined at four days, whereas transmission efficiency was positively correlated with the number of adults used, features linked to the virus semipersistent mode of transmission.