First Report of Tomato Leaf Curl New Delhi Virus Infecting Cucurbit Plants in Algeria

Abstract

HomePlant DiseaseVol. 103, No. 12First Report of Tomato Leaf Curl New Delhi Virus Infecting Cucurbit Plants in Algeria PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Tomato Leaf Curl New Delhi Virus Infecting Cucurbit Plants in AlgeriaA. Kheireddine, A. Sifres, C. Sáez, B. Picó, and C. LópezA. KheireddineInstitute for the Conservation and Breeding of Agricultural Biodiversity, Universitat Politècnica de València, 46022 Valencia, SpainUniversity Mohamed Khider Biskra, 07000 Biskra, AlgeriaSearch for more papers by this author, A. SifresInstitute for the Conservation and Breeding of Agricultural Biodiversity, Universitat Politècnica de València, 46022 Valencia, SpainSearch for more papers by this author, C. SáezInstitute for the Conservation and Breeding of Agricultural Biodiversity, Universitat Politècnica de València, 46022 Valencia, SpainSearch for more papers by this author, B. PicóInstitute for the Conservation and Breeding of Agricultural Biodiversity, Universitat Politècnica de València, 46022 Valencia, SpainSearch for more papers by this author, and C. López†Corresponding author: C. López; E-mail Address: clopez@upvnet.upv.eshttp://orcid.org/0000-0001-7459-1315Institute for the Conservation and Breeding of Agricultural Biodiversity, Universitat Politècnica de València, 46022 Valencia, SpainSearch for more papers by this author AffiliationsAuthors and Affiliations A. Kheireddine1 2 A. Sifres1 C. Sáez1 B. Picó1 C. López1 † 1Institute for the Conservation and Breeding of Agricultural Biodiversity, Universitat Politècnica de València, 46022 Valencia, Spain 2University Mohamed Khider Biskra, 07000 Biskra, Algeria Published Online:16 Oct 2019https://doi.org/10.1094/PDIS-05-19-1118-PDNAboutSections ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat In June 2018, zucchini (Cucurbita pepo), melon (Cucumis melo), and cucumber (Cucumis sativus) plants showing virus-like symptoms such as foliar yellowing and vein clearing were observed in the agricultural region of Biskra, in northeast Algeria. A total of 51 symptomatic leaf samples were collected: 31 of zucchini, 12 of cucumber, and eight of melon. To investigate the etiology of the observed disease, leaf extracts were subjected to total RNA extraction with TRIzol reagent. Virus identification was carried out by nucleic acid spot hybridization using specific riboprobes for tomato leaf curl New Delhi virus (ToLCNDV, genus Begomovirus, family Geminiviridae), cucurbit yellows stunting disorder virus, cucumber vein yellowing virus, cucumber mosaic virus, watermelon mosaic virus, Moroccan watermelon mosaic virus, Algerian watermelon mosaic virus, zucchini yellow mosaic virus, and cucumber green mottle mosaic virus. A hybridization signal was observed for all symptomatic leaf samples with the ToLCNDV riboprobe, whereas no signal was observed for samples from zucchini plants grown in a virus-free facility. Moreover, the presence of any of the other abovementioned viruses was not observed in any of the analyzed samples. To confirm the identity of the virus, DNA was isolated from 24 symptomatic samples (12 of zucchini, six of melon, and six of cucumber) with the CTAB method and was subsequently analyzed by PCR with two ToLCNDV-specific primer pairs (To-A1F and To-A1R from the DNA-A; To-B1F and To-B1R from the DNA-B) (Sáez et al. 2016) to amplify 505- and 677-bp fragments of viral DNAs A and B, respectively. PCR products of the expected size were observed on 1% agarose gel for all of the symptomatic samples. Two randomly selected PCR fragments of each host were bidirectionally sequenced and confirmed as ToLCNDV. The nucleotide sequences of these amplicons were essentially identical irrespective of the host. The complete DNA-A and DNA-B genomic sequences of a ToLCNDV isolate from cucumber (ToLCNDV-Biskra) were obtained as described by Sifres et al. (2018) and deposited in GenBank under accessions numbers MK981891 and MK981892. Alignments of the obtained sequences of DNA-A and DNA-B using the Muscle method in SDT version 1.2 (Muhire et al. 2014) revealed identities of 98.7 and 97.6%, respectively, with the corresponding segments of the isolates from the Mediterranean basin, whereas the identity with isolates from Asia was around 90 and 81% for DNA-A and DNA-B, respectively. Tests conducted by PCR with conserved primers for betasatellites and alphasatellites (Briddon et al. 2002; Bull et al. 2003) were negative, and an additional test by PCR with conserved primers for begomoviruses (Alfaro-Fernández et al. 2016) did not detect any other begomovirus. Moreover, because the Mediterranean basin isolates are mechanically transmitted (López et al. 2015), experiments were conducted using dehydrated tissue of some of the cucumber plants naturally infected with ToLCNDV as a source of inoculum to inoculate seedlings of zucchini accession MU-CU-16, highly susceptible to this virus. Ten days postinoculation, ToLCNDV infection was confirmed by PCR amplification and additionally confirmed by DNA sequencing. In the Mediterranean basin, ToLCNDV has been reported in Spain, Italy, Greece, Tunisia, and Morocco infecting different cucurbit crops, but to our knowledge, this is the first report of the presence of ToLCNDV in Algeria. Further disease monitoring and the establishment of effective control measures will be necessary for disease management to minimize yield losses.The author(s) declare no conflict of interest.