Validation of ToLCNDV resistant germplasm in melon (Cucumis melo) and cucumber (Cucumis sativus) through challenged inoculation

The study was carried out to validate the Tomato Leaf Curl New Delhi Virus (ToLCNDV) resistance in four promising accessions of melon (Cucumis melo L.) and cucumber (Cucumis sativus L.) accessions, viz. IC629818-A, IC629818-B, IC629821, and IC410617 along with checks PI 124111, Pusa Uday and Punjab Naveen through artificial inoculation at glasshouse facility of ICAR-IARI, New Delhi, during 2024-25. These lines were identified through field screening against ToLCNDV during the kharif seasons of 2021–2024 at the ICAR-NBPGR, New Delhi. Under artificial inoculation in the glasshouse, accessions IC629818-A and IC629818-B exhibited no visible symptoms of ToLCNDV and recorded a vulnerability index of 0. PCR amplification had further confirmed the absence of viral infection in these lines. This is perhaps the first report wherein any melon germplasm showed immune/highly resistant reaction to ToLCNDV. The cucumber genotype IC410617 had little symptom (VI=4.5) with no amplification of viral coat protein and thus categorized as resistant. These lines show potential for their utilization as novel sources of resistance for breeding of ToLCNDV-resistant cucumber and melon cultivars.