First Report of Zucchini yellow mosaic virus Associated with Leaf Crinkle and Yellow Mosaic Diseases of Cucurbit Plants in Mali.

The aphid-transmitted Zucchini yellow mosaic virus (ZYMV; genus Potyvirus, family Potyviridae) has been reported to cause severe epidemics and yield losses in cucurbit crops worldwide (1). In Africa, ZYMV has been detected in Algeria, Egypt, Madagascar, Mauritius, Mayotte, Morocco, Nigeria, Reunion, South Africa, Sudan, Swaziland, and Tunisia (1). In April 2009, leaf yellowing, mosaic, crinkling, and curling were common on cucurbit plants in fields in Mali. Symptomatic leaf samples were collected from five cucumber (Cucumis sativus) plants in Kati, two watermelon (Citrullus lanatus) plants in Samanko, and one weedy melon (Cucumis sp.) plant in Baguineda. All samples tested positive for ZYMV and were negative for Cucumber mosaic virus (CMV), Cucumber green mottle mosaic virus (CGMMV), Papaya ringspot virus type W (PRSV-W), Watermelon mosaic virus (WMV), and Watermelon silver mottle virus (WSMoV) by double-antibody sandwich (DAS)-ELISA. They also tested negative for Melon yellow spot virus (MYSV) by indirect ELISA. Antibodies against ZYMV and WMV were obtained from DSMZ, Braunschweig, Germany, and those against CGMMV, MYSV, PRSV-W, and WSMoV were provided by Shyi-Dong Yeh, National Chung Hsing University, Taichung, Taiwan. Six ZYMV ELISA-positive samples (three cucumber, two watermelon, and the weedy melon sample) were also tested by reverse transcription (RT)-PCR using the potyvirus universal primer pair Sprimer1/Oligo(dT) (2). The expected 1.6-kb viral cDNA was amplified from all six samples and each was sequenced. All sequences obtained from cucumber (GenBank Accession Nos. HM005307, HM005308, and HM005309), watermelon (GenBank Accession Nos. HM005311 and HM005312), and weedy melon (GenBank Accession No. HM005310) isolates were 1,684 nucleotides (nt) long excluding the 3' poly-A tails. They comprised the 3'-terminal of the NIb region (1 to 633 nt), the coat protein region (634 to 1473 nt), and the 3'-untranslated region (1,474 to 1,684 nt). Because the sequences shared high nucleotide identity (98.3 to 99.7%), these isolates were considered to be the same virus species. When the sequences were compared by BLASTn searching in GenBank and analyzed by DNAMAN Sequence Analysis Software (Lynnon Corporation, St-Louis, Pointe-Claire, Quebec, Canada), they were found to have the greatest nucleotide identity (97.4 to 98.0%) with the Connecticut strain of ZYMV (ZYMV-Connecticut; GenBank Accession No. D00692), within a clade of isolates from China, Italy, Japan, and the United States. When assessed separately, their coat protein (97.7 to 98.3% nucleotide and 98.9 to 99.6% amino acid identity) and 3'-untranslated regions (96.7 to 97.2% identity) also had greatest homology with ZYMV-Connecticut. To our knowledge, this is the first report of ZYMV infecting cucurbit plants in Mali. ZYMV should be taken into consideration when breeding cucurbit crops for this region, and managing viral diseases. References: (1) C. Desbiez et al. Plant Pathol. 46:809, 1997. (2) W. S. Tsai et al. Plant Dis. 94:378, 2010.

First Report of Pepper veinal mottle virus Associated with Mosaic and Mottle Diseases of Tomato and Pepper in Mali.

The aphid-transmitted Pepper veinal mottle virus (PVMV; genus Potyvirus, family Potyviridae) has been reported as causing an epidemic in solanaceous crops, including eggplant, pepper, and tomato in Africa (4). In West Africa, PVMV has been detected in Senegal, Sierra Leone, Ivory Coast, Ghana, Togo, Burkina Faso, and Nigeria (2). In April 2009, leaf yellowing, mosaic, mottle, and curling symptoms indicative of viral infection were common on tomato (Solanum lycopersicum) and pepper (Capsicum annuum) plants in home gardens and fields in Mali. Symptomatic leaf samples were collected from two sweet pepper and two tomato plants from Baguineda, four tomato plants and one chili pepper plant in Kati, and three chili pepper plants from Samanko. All samples except two chili pepper from Samanko and two sweet pepper and two tomato from Baguineda tested positive for begomovirus by PCR with primers PAL1v1978/PAR1c715 (3). PVMV was detected by double-antibody sandwich (DAS)-ELISA using PVMV antibody (DSMZ, Braunschweig, Germany) in both Baguineda sweet pepper, one Baguineda tomato, and one Samanko chili pepper sample. Three PVMV ELISA-positive samples, one each of sweet pepper, chili pepper, and tomato, were also confirmed by reverse transcription (RT)-PCR and sequencing. The expected 1.8-kb viral cDNA was amplified from all three samples using the potyvirus general primer Sprimer1 (5'-GGNAAYAAYAGHGGNCARCC-3'), which was modified from the Sprimer (1) as upstream primer, and Oligo(dT) (5'-GCGGGATCCCTTTTTTTTTTTTTTTTTT-3') as downstream primer. The sequences obtained from chili pepper (GenBank Accession No. GQ918274), sweet pepper (GenBank Accession No. GQ918275), and tomato (GenBank Accession No. GQ918276) isolates, excluding the 3' poly-A tails, were each 1,831 nucleotides (nt) long, comprising the 3'-terminal of the NIb region (1 to 642 nt), the coat protein region (643 to 1,455 nt), and the 3'-untranslated region (1,456 to 1,831 nt). The sequences shared between 99.3 and 99.5% nucleotide identity with each other. A comparison of these sequences with corresponding sequences of potyviruses in GenBank revealed they had greatest nucleotide identity (96.5 to 96.6%) with a tomato isolate of PVMV from Taiwan (PVMV-TW; GenBank Accession No. EU719647), between 81.4 and 95.9% identity with other PVMV isolates, and only as much as 67.2% identity with other potyvirus isolates. Analysis of coat protein regions alone also revealed high nucleotide (96.6 to 96.8%) and amino acid (99.3 to 99.6%) identity with PVMV-TW. The PVMV Baguineda tomato isolate caused mosaic and mottle symptoms on tomato (line CLN1558A) and pepper (cv. Early Calwonder) plants following mechanical inoculation. To our knowledge, this is the first report of PVMV infecting plants in Mali and reinforces the need to take this virus into consideration when breeding tomato and pepper for this region. References: (1) J. Chen et al. Arch. Virol. 146:757, 2001. (2) C. Huguenot et al. J. Phytopathol. 144:29, 1996. (3) M. R. Rojas et al. Plant Dis. 77:340, 1993. (4) G. Thottappilly, J. Phytopathol. 134:265, 1992.

Mycoflora and occurrence of aflatoxin in dried vegetables in Benin, Mali and Togo, West Africa.

Fungal infection and aflatoxin contamination was evaluated on 180 samples of dried vegetables such as okra, hot chilli, tomato, melon seeds, onion and baobab leaves from Benin, Togo and Mali collected in September to October 2006. These products are dried to preserve them for lean periods and decrease their perishability. Fungal contamination was evaluated after plating on selective media with a total of 561 fungal isolates identified, ranging from 18 in tomato and 218 in baobab leaves. Baobab leaves, followed by hot chilli and okra showed high incidence of fungal contamination compared to the other dried vegetables, while shelled melon seeds, onion leaves and dried tomato had lower levels of fungal contamination. Species of Aspergillus were dominant on all marketed dried vegetables irrespective of country. Mycotoxin assessment by Reversed-Phase High Performance Liquid Chromatography showed that only okra and hot chilli were naturally contaminated with aflatoxin B(1) and aflatoxin B(2), at concentrations of 6.0 microg/kg on okra and 3.2 microg/kg on hot pepper. This is the first time that mycotoxigenic fungi and resultant toxins were found on dried vegetable products sampled from African markets. Previous reports have mostly highlighted the risk of mycotoxin exposure from staple crops in Africa, but such risks now need to be evaluated for other products such as dried vegetables.