Asma Najar

A Survey of Viruses Affecting Faba Bean (Vicia faba) in Tunisia Includes First Record of Soybean dwarf virus

A survey was conducted in April 2003 to identify viruses infecting faba bean (Vicia faba L.) in six regions (Beja, Bizerte, Cap-bon, Le Kef, Siliana, and Zaghouan) in Tunisia. A total of 292 faba bean samples with symptoms of viral infection (leaf rolling, yellowing, and mosaic) were collected. The samples were tested at the virology laboratory of the International Center for Agricultural Research in the Dry Areas (ICARDA), Syria, for 11 viruses using the tissue-blot immunoassay procedure (3). Specific rabbit polyclonal antisera were used to test for Chickpea chlorotic dwarf virus (CpCDV) (provided by H. J. Vetten, BBA, Braunschweig, Germany), Alfalfa mosaic virus (AMV), Bean yellow mosaic virus (BYMV), Broad bean mottle virus (BBMV), Broad bean stain virus (BBSV), Cucumber mosaic virus (CMV), and Pea seedborne mosaic virus (PSbMV) (ICARDA, Aleppo, Syria). In addition, four specific monoclonal antibodies were used to detect Bean leaf roll virus (BLRV) (4B10) (2), Beet western yellows virus (BWYV) (ATCC PVAS-647; American Type Culture Collection, Manassas, VA), Faba bean necrotic yellows virus (FBNYV) (3-2E9) (1), and Soybean dwarf virus (SbDV) (ATCC PVAS-650). Serological tests showed that BBMV, a beetle-transmitted and seedborne virus identified in 23.3% (68 samples) of the samples tested, was the most common. BLRV, FBNYV, BWYV, BYMV, SbDV, and PSbMV were detected in 56, 33, 31, 10, 5, and 1 sample(s) of 292 samples tested, respectively. AMV, BBSV, CMV, and CpCDV were not detected in any samples tested. In Tunisia, BLRV, BWYV, BYMV, FBNYV, and PSbMV have previously been reported in faba bean (4), but to our knowledge, this is the first record of SbDV affecting faba bean in Tunisia, where it was detected in two fields in the Cap-bon Region. In sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by western blots, extracts from SbDV-infected plants were observed to contain 23-kDa structural proteins, which reacted strongly with SbDV monoclonal antibodies. Transmission tests showed that the samples, which reacted with SbDV monoclonal antibodies, were transmitted to faba bean plants by the pea aphid (Acyrthosiphon pisum Harris) in a persistent manner. To our knowledge, this is the first report of SbDV naturally infecting faba bean in Tunisia and it could cause a serious problem to other leguminous crops grown in Tunisia, such as French bean and peas, which are hosts for the virus. References: (1) A. Franz and K. M. Makkouk Ann. Appl. Biol. 128:255, 1996. (2) L. Katul. Characterization by serology and molecular biology of bean leaf roll virus and faba bean necrotic yellows virus. PhD thesis. University of Gottingen, Gottingen, Germany, 1992. (3) K. M. Makkouk and A. Comeau. Eur. J. Plant Pathol. 100:71, 1994. (4) A. Najar et al. Phytopathol. Mediterr. 39:423, 2000.

First record of faba bean necrotic yellows virus and beet western yellows virus infecting faba bean in Tunisia.

A survey was conducted in April 2000 to identify viruses infecting faba bean (Vicia faba L.) in seven regions (Beja, Bizerte, Cap-bon, Jendouba, Kairouan, Siliana, and Zaghouan) of Tunisia. Around 4,000 random samples were collected from 34 fields (100 to 200 samples per field). Samples were tested by tissue-blot immunoassay procedure (2) at the Virology Laboratory of INRAT for the presence of 14 different viruses. All antisera used were specific, including those for Faba bean necrotic yellows virus (FBNYV) (1) and Beet western yellows virus (BWYV) (ATCC-PVAS-647). Broad bean mottle, a beetle-transmitted and seedborne virus, was the most abundant with an average incidence of 2.3%. The highest disease incidence occurred with BWYV, which was in 20 and FBNYV in 4 of 98 random samples from a field in the Siliana region; and with BWYV in 7 and BBMV in 21 of 120 samples from a field in the Jendouba region. Other viruses such as broad bean stain, cucumber mosaic, and bean leaf roll were detected rarely (<1%). This is the first record of FBNYV and BWYV infecting faba bean in Tunisia. BWYV was detected in 1.2% of the samples tested collected from 20 fields comprising all seven regions. FBNYV was detected in 0.9% of the samples tested collected from 13 fields comprising all except the Capbon region. References: (1) A. Franz et al. Ann. Appl. Biol. 128:255, 1996. (2) K. M. Makkouk and A. Comeau. Eur. J. Plant Pathol. 100:71, 1994.

First Record of Barley yellow striate mosaic virus, Barley stripe mosaic virus, and Wheat dwarf virus Infecting Cereal Crops in Tunisia

A survey conducted during April 2000 to identify viruses infecting cereal crops in different regions (Beja, Bizerte, Cap-bon, Jendouba, Kairouan, Siliana, and Zaghouan) of Tunisia covered 15 barley, 21 durum wheat, and 7 bread wheat randomly selected fields. Virus incidences were determined on the basis of laboratory testing of 100 to 200 randomly collected samples from each field. A total of 5,227 random (1,654 barley, 2,546 durum wheat, and 1,027 bread wheat) and 1,430 symptomatic (451 barley, 746 durum wheat, and 233 bread wheat) samples were collected. Samples were tested for the presence of five different viruses by tissueblot immunoassay (TBIA) (1) at the Virology Laboratory of INRAT. Antisera used were for Barley stripe mosaic virus (2), Barley yellow dwarf virus (PAV serotype) (2), Wheat streak mosaic virus (3), Barley yellow striate mosaic virus (BYSMV) provided by E. Luisoni, IFA, Turino, Italy (4), and Wheat dwarf virus (WDV) provided by J. Vacke, Research Institute of Crop Production, Prague, Chech Republic. BYDVPAV was detected in seven barley (from three fields), 25 durum wheat (10 fields), and eight bread wheat (three fields) samples from all except the Siliana region. BYSMV was detected in three barley (three fields), 16 durum wheat (six fields), and four bread wheat (three fields) samples from the Beja, Bizerte, Cap-bon, Jendouba, and Siliana regions. WDV was detected in five barley (three fields), nine durum wheat (four fields), and four bread wheat (one field) samples from the Beja, Cap-bon, and Bizerte regions. BSMV was detected in 49 barley (six fields) and 25 durum wheat (five fields) samples from the Beja, Bizerte, Cap-bon, Kairouan, and Zaghouan regions. This is the first record of BYSMV, BSMV, and WDV infecting cereal crops in Tunisia, but their incidence in fields was less than 1%. However, BSMV incidence was 10.5% in one barley field from the Cap-bon region. Virus incidence in symptomatic plants was a bit higher and ranged from 0.8% for WDV in bread wheat to 6% for BSMV in barley. References: (1) K. M. Makkouk and A. Comeau. Eur. J. Plant Pathol. 100:71, 1994. (2) K. M. Makkouk and S. G. Kumari. Rachis Newsl. 12(1/2):24, 1993. (3) K. M. Makkouk and S. G. Kumari. Rachis Newsl. 16(1/2):74, 1997. (4) R. G. Milne et al. Intervirology 25:83, 1986.

Introgression of barley yellow dwarf virus resistance into Tunisian barley varieties

Abstract: The original objective of cross breeding was to develop high-yielding spring barley with high barley yellow dwarf virus resistance. Imen is an F5-derived line with the original experimental number 137. A single seed selection breeding method was used to develop the cultivar. Imen is well adapted to semi-arid areas, carrying the resistant gene Yd2.

Sélection de lignées d’orge (Hordeum vulgare L.) pour leur résistance au barley yellow dwarf virus (BYDV) et évaluation de leurs performances agronomiques

Abstract: Le virus de la jaunisse nanisante de l’orge ou « barley yellow dwarf virus » (BYDV) est connu comme étant le virus le plus important se répandant sur les céréales. En Tunisie, les contaminations peuvent dépasser 40 % sur orge dans certaines régions. La sélection de génotypes résistants constitue le moyen le plus propice pour la lutte contre le BYDV. Ainsi, une sélection à partir de 10 populations d’orge F2 fournis par le Centre International de Recherche Agricole dans les Zones Arides (ICARDA) dont certains parents sont porteurs du gène de résistance Yd2, a été entreprise. De la F2 à la F5, 198 lignées avancées ont été sélectionnées pour leur résistance. Cette résistance a été évaluée, sur les plans symptomatique, sérologique et moléculaire par l’utilisation du marqueur Ylp (CAPS) associé au gène cible (Yd2). Une évaluation agronomique de ces lignées a été réalisée durant la campagne 2006--2007, à Béja (région subhumide) et au Kef (région semi-aride). Le choix particulièrement basé sur le rendement en grains a porté sur 25 lignées qui étaient toutes supérieures au cultivar sensible « Rihane » mais dont huit seulement dépassent l’autre cultivar sensible « Manel ». Parmi ces lignées, 16 pourraient être destinées à l’exploitation à double fin (grains et paille) alors que deux ont montré une souplesse d’adaptation à la fois aux conditions semi-arides et subhumides.