# First report of Tomato leaf curl New Delhi virus infecting courgette in France

Cecile Desbiez, Pascal Gentit, Pascaline Cousseau-Suhard, Isabelle Renaudin, Eric Verdin

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Cecile Desbiez, Pascal Gentit, Pascaline Cousseau-Suhard, Isabelle Renaudin, Eric Verdin. First report of Tomato leaf curl New Delhi virus infecting courgette in France. New Disease Reports, 2021, 42 (2), pp.e12006. 10.1002/ndr2.12006. hal-03230529

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Submitted on 20 May 2021

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# First report of *Tomato leaf curl New Delhi virus* infecting courgette in France

C. Desbiez<fnref n="1" /> ID | P. Gentit<fnref n="2" /> | P. Cousseau-Suhard<fnref n="2" /> | I. Renaudin<fnref n="2" /> | E. Verdin<fnref n="1" />

**Correspondence**

Email: Cecile.desbiez@inrae.fr

**KEYWORDS**

begomovirus, cucurbit

Viruses constitute important problems for cucurbit production. In France, aphid-transmitted viruses remain the most important (Desbiez et al., 2020), but whitefly-transmitted viruses, particularly begomoviruses, now emerging in the Mediterranean Basin (Lecoq & Desbiez, 2012) constitute major threats.

A few plants showing leaf crumpling, yellowing and downward curling were observed in a courgette (Cucurbita pepo) plot in Bouches-du-Rhône department (southeastern France) in September 2020. The symptoms were similar to those of *Tomato leaf curl New Delhi virus* (ToLCNDV), an emerging bipartite begomovirus affecting cucurbits in the Mediterranean Basin (Fortes et al., 2016). After DNA extraction, PCR was performed on a symptomatic sample (CD20001) with specific primers TLCNDV-CP-5 and TLCNDV-CP-3, and ToLCNDV-B-900-5 and ToLCNDV-B-1940-3 (Romay et al., 2019) targeting ToLCNDV DNA-A and DNA-B respectively. The amplified fragments (760 bp and 1072 bp) displayed 99.1% and 99.6% identity respectively to ToLCNDV isolate MU.12.ZU/1/2 (MH577761) from Spain. To complete the sequence of DNA-A, PCR amplification was performed with primers TLCNDV-fCP-F (5'-GTGACGGGAGGAACRTATGC-3') and TLCNDV-dCP-R (5'-CTAACACACATGACTTTGCC-3') before sequencing. For DNA-B, rolling circle amplification (RCA) was performed on the extracted DNA with the TempliPhi kit (GE Healthcare). A 2.7 Kb fragment was obtained after digestion with BamHI and cloned in linearised pBlueScript(KS)+ before sequencing. Two clones were sequenced and were identical. The complete sequences of DNA-A and DNA-B (GenBank Accession Nos. MW310624 and MW310625. respectively) were 98-99% identical to isolates from the "Mediterranean" ToLCNDV clade (Fortes et al., 2016).

<figure><img src="image_2.png" /><figcaption>**FIGURE 1** Foliar symptoms in a zucchini plot in which *Tomato leaf curl New Delhi virus* was detected in September 2021 in Bouches-du-Rhône, southeastern France</figcaption></figure>

Five other symptomatic courgette plants were collected in the same plot and 12 plants in two other plots in Bouches-du-Rhône, at a distance of 10 km (8 plants) and 6 km (4 plants) respectively from the first plot (Figure 1). Four courgette samples with similar symptoms were also collected in Gard department, 30 km away from the first plot. The samples were tested by PCR with primers Beg-CP-F and Beg-580-R (Saison et al., 2015). A 580 bp product was obtained for 17 of the 21 tested samples (3/5 in the first plot, 8/8 and 4/4 respectively in the two

<footnote n="1">¹ Inrae, Pathologie Végétale, Montfavet F-84140, France</footnote>

<footnote n="2">² Anses, LSV-BVO, Angers F-49044, France</footnote>
<figure><img src="image_3.png" /></figure>

other plots in Bouches-du-Rhône and 2/4 in Gard) and determined as ToLCNDV by sequencing, confirming the presence of the virus in all four areas. The sequences displayed 99.3-100% identity with isolate CD20001.

<figure><img src="image_4.png" /><figcaption>**FIGURE 2** Foliar symptoms in a zucchini plot in which *Tomato leaf curl New Delhi virus* was detected in September 2021 in Bouches-du-Rhône, southeastern France</figcaption></figure>

<figure><img src="image_5.png" /><figcaption>**FIGURE 3** Fruit symptoms in a zucchini plot in which *Tomato leaf curl New Delhi virus* was detected in September 2021 in Bouches-du-Rhône, southeastern France</figcaption></figure>

This is the first report of ToLCNDV in France. Since ToLCNDV is highly damaging in cucurbits and is a quarantine pest in Europe, it is important to prevent its emergence in France, particularly in the southeast which constitutes France's most important cucurbit production area. The presence of ToLCNDV in four locations within a 30 km range suggests that it has begun to spread efficiently or that multiple introductions have occurred. It is now important to prevent virus overwintering in weeds (Juárez et al., 2019) and be careful to detect and eradicate potential infections in the next growing season.

ORCID

C. Desbiez https://orcid.org/0000-0001-8691-7423

References

Desbiez C, Wipf-Scheibel C, Millot P, Berthier K, Girardot G, Gognalons P, Hirsch J, Moury B, Nozeran K, Piry S, Schoeny A, Verdin E, 2020. Distribution and evolution of the major viruses infecting cucurbitaceous and solanaceous crops in the French Mediterranean area. *Virus Research* 286, 198042. https://doi.org/10.1016/j.virusres.2020.198042

Fortes IM, Sánchez-Campos S, Fiallo-Olivé E, Díaz-Pendón JA, Navas-Castillo J, Moriones E, 2016. A novel strain of tomato leaf curl New Delhi virus has spread to the Mediterranean basin. *Viruses* 8, 307. https://doi.org/10.3390/v8110307

Juárez M, Rabadán MP, Martínez LD, Tayahi M, Grande-Pérez A, Gómez P, 2019. Natural hosts and genetic diversity of the emerging tomato leaf curl New Delhi virus in Spain. *Frontiers in Microbiology* 10, 140. https://doi.org/10.3389/fmicb.2019.00140

Lecoq H, Desbiez C, 2012. Viruses of cucurbit crops in the Mediterranean region: an ever-changing picture. *Advances in Virus Research* 84, 67–126. https://doi.org/10.1016/B978-0-12-394314-9.00003-8

Romay G, Pitrat M, Lecoq H, Wipf-Scheibel C, Millot P, Girardot G, Desbiez C, 2019. Resistance against melon chlorotic mosaic virus and tomato leaf curl New Delhi virus in melon. *Plant Disease* 103, 2913–2919. https://doi.org/10.1094/PDIS-02-19-0298-RE

Saison A, Gentit P, 2015. Development of a polyvalent detection method for Begomoviruses presenting a threat to the European tomato industry. Testa – EPPO conference on diagnostics for plant pests, Angers, France, 30/11/2015 to 02/12/2015. https://www.eppo.int/media/uploaded_images/MEETINGS/Meetings_2015/testa_angers/21_Gentit.pdf. Accessed 2 December 2020.

**How to cite this article:** Desbiez C, Gentit P, Cousseau-Suhard P, Renaudin I, Verdin E, First report of *Tomato leaf curl New Delhi virus* infecting courgette in France. *New Dis Rep.* 2021;43, e12006. https://doi.org/10.1002/ndr2.12006