Etiology of Leaf Chlorosis and Deterioration of the Fruit Interior of Watermelon Plants

A severe disease with combined symptomatology affecting only grafted watermelon plants appeared in several regions of northern and central Greece during the summers of 1999 and 2000. Disease symptoms included chlorotic mottling followed by pedicel necrosis at a later more mature fruit stage, and finally decomposition of fruit interior. Electron microscopy, double antibody sandwich enzyme-linked immunosorbent assay tests and reverse transcriptase-polymerase chain reaction assays identified Cucumber green mottle mosaic virus (CGMMV) as the causal agent. Our studies indicated that the CGMMV isolates from watermelon are closely related to the Israeli variant of CGMMV (CGMMV-Is). However, bioassays revealed that the Greek isolates elicit symptoms of higher severity and have a wider host range, compared with other described CGMMV isolates. Nucleotide sequence comparison of the movement protein gene of the Greek isolates showed a 97–99% identity with other CGMMV strains. This paper reports the presence of the virus in arable weeds such as Amaranthus blitoides, Amaranthus retroflexus, Heliotropium europaeum, Portulaca oleracea and Solanum nigrum.