Lettuce necrotic leaf curl virus: a new torradovirus found in the Netherlands and France
Lettuce necrotic leaf curl virus (LNLCV) is a recently described virus which was first observed in 2011 in a single lettuce (Lactuca sativa) field in the Netherlands. In this open field, approximately 30 irregularly distributed lettuce plants, were showing disease symptoms. The virus was initially isolated from a lettuce plant which was showing conspicuous symptoms of necrosis and moderate leaf curling. In 2015, LNLCV was accepted by the ICTV as a new member of the genus Torradovirus. Later studies conducted in the Netherlands showed that unlike other torradoviruses, LNLCV is not transmitted by whiteflies but by aphids. During experiments, LNLCV was successfully transmitted by Nasonovia ribisnigri. The virus could also be detected in the stylets of Cavariella aegopodii suggesting that it might be a potential vector, but no transmission could be obtained.
In October 2019, a symptomatic lettuce plant (Lactuca sativa cv. Tregoney) was collected in an open field in South-Western France. Symptoms included stunted and deformed leaves with light necrosis and yellow spotting along minor veins of older leaves. Molecular tests (HTS, RT-PCR) and inoculation to herbaceous indicators confirmed the presence of LNLCV. As no other viruses were detected, LNLCV is likely to be responsible for the mild necrosis and leaf deformation symptoms observed in the lettuce plant. It is noted that further studies are needed to better understand the distribution and potential impact of LNLCV to lettuce crops.
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