Confirmation incidence of Tomato chlorosis virus naturally infecting tomato crop in Egypt.
During the 2017-2018 growing season, an unusual disease was observed in tomatoes grown in different locations in Fayoum, Giza, and Nobaria in Egypt. A total of 36 naturally infected tomato plants consists of twenty asymptomatic and sixteen symptomatic tomato leaf samples showing interveinal yellowing, reddish-bronze necrosis, downward rolling and bronzing symptoms, early senescence, leaf brittleness, interveinal were collected. All samples were tested with DAS-ELISA using polyclonal and/or monoclonal antisera against several important tomato viruses. The obtained results revealed that, 5 out of 36 samples, were singly infected with tomato chlorosis virus (ToCV) and one sample was singly positive for begomovirus. Potato virus Y (PVY), cucumber mosaic virus (CMV), tobacco mosaic virus (TMV), and pepino mosaic virus (PeMV) were singly detected in 4, 3, 4 and one out of 36 samples, respectively. Two samples had mixed infection of PVY with CMV and TMV with PVY. Reverse-transcriptase polymerase chain reaction results revealed that ToCV was detected in 5 ELISA positive samples, giving a 463 bp ToCV-specific DNA fragment while only one sample was amplified (587 bp) with begomoviruses primers. Sequence analyses of 27 ToCV isolates obtained from GenBank and compared with the five isolates found in this study. All the Egyptian isolates shared high nucleotide identity among themselves (96.8-100%), while their identity matched 93.4-100% with those published in NCBI-GenBank. There was low genetic diversity between all ToCV isolates examined. To our knowledge, this is the first analytical study regarding the presence of ToCV in tomato crops in Egypt.