A distinct strain of tomato leaf curl New Delhi virus that causes mosaic disease in ash gourd and other cucurbitaceous crops

Abstract

Ash gourd (Benincasa hispida) is a cucurbitaceous crop cultivated as an edible vegetable rich in vitamins, minerals, dietary fibers and antioxidants. In a field survey conducted in the Udumalpet region of Tamil Nadu during 2019, the incidence of mosaic disease on ash gourd crop was observed to be 75%. The DNA-A and DNA-B components of begomovirus genome have been identified as associated with this disease. Both the cloned DNA-A and DNA-B genomic components shared highest pairwise sequence identities with the isolates of tomato leaf curl New Delhi virus (ToLCNDV), a bipartite begomovirus. Recombinant analysis showed that both the components are possibly evolved through intra-species recombination between ToLCNDV isolates. Tomato leaf curl Bangladesh betasatellite (ToLCBB) is not naturally associated with this sample. The results of infectivity studies on ash gourd and other cucurbitaceous crops demonstrates the Koch’s postulates, when co-inoculation of DNA-A and DNA-B of ToLCNDV was undertaken. However, the inoculation of non-cognate ToLCBB along with DNA-A and DNA-B enhances the symptom expression and reduces the time taken for symptom development. Thus, Koch’s postulates were proved for these virus complexes on cucurbitaceous crops. Furthermore, an enhanced accumulation of DNA-A component was detected in the cucurbits co-inoculated with ToLCNDV and ToLCBB. This report highlights the importance of investigating the spread of these disease complexes with other cucurbitaceous crops in India.

Molecular confirmation of ToLCNDV resistance in cucumber (Cucumis sativus L.) genotypes through agroinoculation and field screening

“…According to PCR results, the samples resulted positive for GKNDV DNA-A primer displayed ampli cation of DNA-Aband at an amplicon size of 630 bp was seen in symptomatic leaves of DC 773, 769 and P-85genotypescon rmed the presence of ToLCNDV infection transmitted by Agrobacterium mediated agroinoculation were showed in Fig. 2a &2b.Likewise, molecular detection employing begomovirus-speci c deng primers and coat protein gene primers revealed the ToLCNDV presence in bitter gourd samples reported by Kiran et al ( 2021) and similar tendency on amplicon size of 630 bp in agroinocuated cucurbits crops for ToLCNDV coat protein DNA-A gene through conventional PCR was previously reported by Vignesh et al (2023) in cucurbitaceous crops and. However, no such amplicon was found in symptomless leaf samples of DC 70 as con rmed through PCR assay.…”

“…A speci c degenerative primer GKNDV DNA-A was used to detect the presence of coat protein gene of ToLCNDV in all the agroin ltrated leaf samples (Vignesh et al 2023). The assay of ToLCNDV infection was assured by PCR ampli cation of leaf samples.…”