Abstract
Tomato leaf curl New Delhi virus (ToLCNDV) is a severe threat for cucurbit production worldwide. Resistance has been reported in several crops, but at present, there are no described accessions with resistance to ToLCNDV in cucumber (Cucumis sativus). C. sativus var. sativus accessions were mechanically inoculated with ToLCNDV and screened for resistance, by scoring symptom severity, tissue printing, and PCR (conventional and quantitative). Severe symptoms and high load of viral DNA were found in plants of a nuclear collection of Spanish landraces and in accessions of C. sativus from different geographical origins. Three Indian accessions (CGN23089, CGN23423, and CGN23633) were highly resistant to the mechanical inoculation, as well as all plants of their progenies obtained by selfing. To study the inheritance of the resistance to ToLCNDV, plants of the CGN23089 accession were crossed with the susceptible accession BGV011742, and F1 hybrids were used to construct segregating populations (F2 and backcrosses), which were mechanically inoculated and evaluated for symptom development and viral load by qPCR. The analysis of the genetic control fit with a recessive monogenic inheritance model, and after genotyping with SNPs distributed along the C. sativus genome, a QTL associated with ToLCNDV resistance was identified in chromosome 2 of cucumber.
Highlights
Cucurbits are cultivated in tropical, subtropical, and temperate regions of the New andOld world and supply essential vitamins and minerals to current diets in countries around the world, being a major source of food for humans
We evaluated the response to Tomato leaf curl New Delhi virus (ToLCNDV) of a cucumber germplasm collection by mechanical inoculation
Germplasm accessions of cucumber (Cucumis sativus) from different geographical origins were screened for resistance to ToLCNDV
Summary
Cucurbits are cultivated in tropical, subtropical, and temperate regions of the New andOld world and supply essential vitamins and minerals to current diets in countries around the world, being a major source of food for humans. Cucurbits are cultivated in tropical, subtropical, and temperate regions of the New and. Crops belonging to the three most economically important genera, Cucumis (melon and cucumber), Citrullus (watermelon), and Cucurbita (zucchini, pumpkin, squash and gourd), rank in the first positions in global vegetable and fruit production. Spain is one of the main world producers of cucurbits [1], and the first exporting country in Europe. The production of these crops has been severely affected by diseases, in particular those caused by viruses [2,3] that have a high economic impact. Tomato leaf curl New Delhi virus (ToLCNDV), a member of the genus Begomovirus, family Geminiviridae, has spread rapidly in southern Spain since the first detection in 2012 and represents a major risk in the production of zucchini, melon, and cucumber.
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