Abstract
Tomato leaf curl New Delhi virus (ToLCNDV) is a bipartite begomovirus affecting tomato cultivation on the Indian subcontinent. Recently, however, a new strain of the virus, named ToLCNDV-ES, has spread to Mediterranean countries such as Spain, Italy, and Tunisia, and occurred in Cucurbita crops, causing economic damage. Although ToLCNDV is spread by the sweet potato whitefly (Bemisia tabaci), like other begomoviruses, it has not been clear how ToLCNDV suddenly spread from the Indian subcontinent to the Mediterranean region. In 2017, ToLCNDV was diagnosed in young seedlings germinated naturally from fruits fallen in the prior year on a farm located in Giugliano in Campania, Naples, Italy, suggesting a possible role of the seeds in vertical transmission of the virus. Because sweet potato whiteflies were widespread naturally in that region, it was necessary to verify that in an artificial insect vector-free condition. Seeds were harvested from two ToLCNDV-infected zucchini squash cultivars in Naples in 2017 and 2018 to examine whether ToLCNDV can be transmitted from zucchini squash seeds to young plants. Viral DNA was amplified from these seeds and 1- to 3-week-old seedlings germinated from them with a ToLCNDV-specific primer set. According to PCR results, viral contamination was confirmed from all harvested seeds and dissemination was proven from 61.36% of tested seedling samples. Mechanical transmission from seed-borne virus-infected seedlings to healthy zucchini squash plants was also succesful, demonstrating that seedlings from ToLCNDV-infected seeds did act as inoculum. This is the first report demonstrating that ToLCNDV is a seed-transmissible virus in zucchini squash plants in Italy.
Highlights
Tomato leaf curl New Delhi virus (ToLCNDV) is a bipartite begomovirus transmitted by the whitefly Bemisia tabaci and causes total yield loss in tomato cultivation [1,2]
After the first report of leaf curl disease of tomatoes in India [3], 48 species have been reported as tomato leaf curl disease (ToLCD)-related viruses
Plants 2020, 9, 563 which were defined as new species [12,13]. This virus has not been specific to Asia because one of the noble strains of ToLCNDV spread to Spain, named ToLCNDV-ES, which grouped in a different phylogenetic cluster than those reported from Asian countries [14]
Summary
Tomato leaf curl New Delhi virus (ToLCNDV) is a bipartite begomovirus (genus Begomovirus, family Geminiviridae) transmitted by the whitefly Bemisia tabaci and causes total yield loss in tomato cultivation [1,2]. Plants 2020, 9, 563 which were defined as new species [12,13] In recent years, this virus has not been specific to Asia because one of the noble strains of ToLCNDV spread to Spain, named ToLCNDV-ES, which grouped in a different phylogenetic cluster than those reported from Asian countries [14]. Since the first report of ToLCNDV-infected zucchini squash (Cucurbita pepo) in southern Spain, introduction of the same viral strain (i.e., ToLCNDV-ES strain) into other Mediterranean countries including, Italy and Tunisia has damaged cucurbit crops [14,15,16,17,18]. Plant viruses can be transmitted via virus-infected seeds [21], causing their spread beyond the limits of time and place. ToLCNDV-ES populations under field conditions results in seed transmission of the virus
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
