May 27, 2004
From: American Phytopathological Society, Plant Disease Notes [edited]

A new tomato leaf curl virus from Mayotte, French Comoros Archipelago
J. M. Lett, H. Delatte, F. Naze, and B. Reynaud, CIRAD, UMR PVBMT CIRAD-Universite de La Reunion, Pole de Protection des Plantes, Ligne Paradis, 97410 Saint-Pierre, La Reunion, France; A. L. Abdoul-Karime, Laboratoire de la Protection des Vegetaux, BP 103, 97600 Mamoudzou, Mayotte, France; and M. Peterschmitt, CIRAD, UMR BGPI, TA 41/K, 34398 Montpellier Cedex 5, France. Plant Dis. 88:681, 2004; published on-line as D-2004-0401-01N, 2004.
Accepted for publication 17 Mar 2004.

In June 2003, symptoms of stunting and leaf curling resembling symptoms of tomato leaf curl disease, as well as reductions in yields, were observed on tomato plants in the western (Combani and Kahani) and eastern (Dembeni, Kaoueni, and Tsararano) regions of Mayotte, a French island in the Comoros Archipelago located in the northern part of the Mozambique Channel.

The whitefly, _Bemisia tabaci_ (_Gennadius_), was observed colonizing tomato plants and other vegetable crops at low levels. Overall, 13 leaf samples with symptoms were collected from tomato plants among the 5 regions and tested for the presence of begomoviruses using a PCR assay with 2 sets of degenerate primers designed to amplify 2 regions of the A component of begomoviruses.

Primers MP16 and MP82 amplify an approximately 500-bp fragment located between the intergenic conserved nonanucleotide sequence and the first 200 bp of the coat protein (CP) gene (2). Primers AV494 and AC1048 amplify the approximately 550-bp core region of the CP gene (3). 6 leaf samples, one from Combani, 3 from Dembeni, and 2 from Kahani, gave a PCR product of the expected size with both sets of primers. No PCR products were obtained with degenerate primers designed for begomovirus DNA B or beta.

The approximately 500- and 550-bp PCR products from one sample each of Combani (EMBL Accession Nos. AJ620912 and AJ620915, respectively), Dembeni (EMBL Accession Nos. AJ620911 and AJ620914, respectively), and Kahani (EMBL Accession Nos. AJ620913 and AJ620916, respectively) were sequenced. For the 489-bp sequences obtained with the MP16/MP82 primer set, the 3 isolates had 90 to 95 percent nucleotide identity (DNAMAN; Lynnon BioSoft, Quebec).

The most significant sequence alignments (NCBI and BLAST) were with begomoviruses; 80-83 percent nucleotide identity was obtained with the Tomato yellow leaf curl Morondava virus (TYLCMV) isolates from Madagascar (EMBL Accession Nos. AJ422123 and AJ422124), 80 to 82% nucleotide identity was obtained with the South African cassava mosaic virus (SACMV) isolates (GenBank and EMBL Accession Nos. AF155806 and AJ422132), and 79-81 percent nucleotide identity was obtained with the East African cassava mosaic Malawi virus (EMBL Accession No. AJ006460). For the 522-bp sequences obtained with the AV494/AC1048 primer set, 95 to 97% nucleotide identity was shown between the 3 isolates.

The most significant sequence alignments were also with begomoviruses; TYLCMV isolate Morondava (EMBL Accession No. AJ422125) with 86-88 percent nucleotide identity, Tomato yellow leaf curl virus isolates (GenBank and EMBL Accession Nos. AF105975, AJ489258, AB014346, AF024715, AF071228, and X76319) with 86-87 percent nucleotide identity, and SACMV isolate M12 (EMBL Accession No. AJ422132) with 85-86 percent nucleotide identity.

According to the current taxonomic criteria for the provisional classification of a new begomovirus species, nucleotide sequence identity in the core region of the CP <90 percent (1), the tomato begomovirus from Mayotte is a new species and is provisionally named Tomato leaf curl Mayotte virus.

References:
(1) J. K. Brown et al. Arch. Virol. 146:1581, 2001.
(2) P. Umaharan et al. Phytopathology 88:1262, 1998.
(3) S. D. Wyatt and J. K. Brown. Phytopathology 86:1288, 1996.

[The provisional designation of Tomato leaf curl Mayotte virus leaves room for further characterization of the virus and a final decision of the International Committee on Taxonomy of Viruses regarding its taxonomy.

The agricultural sector on Mayotte is divided into subsistence farming and farming for export. Subsistence farming, which provides the staples making up 75 percent of the islanders' diet, consists of coconuts, cassava,
bananas and rice. Small quantities of fish and meat are also consumed. Mayotte is not self-sufficient and must import a large portion of its food requirements, mainly from France. Exports are mainly ylang-ylang (perfume
essence), vanilla, copra, coconuts, coffee, and cinnamon. - Mod.DH]