First Report of Chickpea Chlorotic Dwarf Virus Infecting Spring Chickpea in Syria.

During May 2003, a high incidence of symptoms suggestive of virus infection in spring chickpea were observed in many fields in Al-Ghab Valley, Syria, the ICARDA farm (near Aleppo, Syria), as well as in other locations in northern Syria, including the Idleb governorate. Symptoms observed were yellowing, stunting, and necrosis. A total of 1,345 chickpea samples with these symptoms (331 from Al-Ghab Valley, 269 from the ICARDA farm, and 745 from the Idleb governorate) were collected and tested for the presence of five viruses with tissue-blot immunoassay (TBIA) (4) at the Virology Laboratory of ICARDA, using the following antisera: monoclonal antibodies for Faba bean necrotic yellows virus (FBNYV, genus Nanovirus) (1); Bean leafroll virus (BLRV, family Luteoviridae) (4B10) (3); Beet western yellows virus (BWYV, genus Polerovirus, family Luteoviridae [ATCC PVAS-647, American Type Culture Collection, Manassas, VA]); and Soybean dwarf virus (SbDV, family Luteoviridae, [ATCC PVAS-650]) and polyclonal antibodies for Chickpea chlorotic dwarf virus (CpCDV, genus Mastrevirus, family Geminiviridae, provided by H. J. Vetten, BBA, Braunschweig, Germany). The most common virus present was BWYV (detected in 54.1% of samples tested), followed by CpCDV (19.2%), BLRV (10.2%), and FBNYV (5.5%). SbDV was not detected in any of the samples tested. Using immunosorbent electron microscopy, infected chickpea samples revealed low numbers of geminivirus-like particles after 15 min of incubation on CpCDV antiserum-coated grids. When CpCDV was purified from infected chickpea plants, the virus coat protein was 32 kDa with sodium dodecyl sulfate-polyacrylamide gel electrophoresis typical of CpCDV coat protein (2) and reacted strongly with CpCDV antiserum in western blots. The CpCDV vector in Syria was found to be Orosius albicinctus Distant, and is thought to be similar to Orosius orientalis (Matsumura), the reported vector of CpCDV (2). FBNYV, BWYV, and BLRV infection of chickpea have been previously reported from Syria, but to our knowledge, this is the first report of CpCDV infecting chickpea in Syria. References: (1) A. Franz et al. Ann. Appl. Biol. 128:255, 1996. (2) N. M. Horn et al. Ann. Appl. Biol. 122:467, 1993. (3) L. Katul. Characterization by serology and molecular biology of bean leaf roll virus and faba bean necrotic yellows virus. Ph.D. thesis. University of Gottingen, Germany, 1992. (4) K. M. Makkouk and A. Comeau. Eur. J. Plant Pathol. 100:71, 1994.

First Record of Pea enation mosaic virus Naturally Infecting Chickpea and Grasspea Crops in Syria.

Virus-like symptoms not commonly encountered on most chickpea (Cicer arietinum L.) and grasspea (Lathyrus sativus L.) genotypes were noticed at the ICARDA farm near Aleppo, Syria, during April and May 2001. Primary symptoms included stunting, accompanied by leaf mottling and yellowing. The causal agent was transmitted by the pea aphid (Acyrthosiphon pisum Harris) in a persistent manner. Efficiency of transmission was 100% when aphids acquired the virus from grasspea and then inoculated lentil, whereas transmission efficiency was 21% when aphids acquired the virus from chickpea and then inoculated lentil. Samples of symptomatic chickpea and grasspea reacted strongly with the antiserum prepared against a Dutch isolate (E154) of Pea enation mosaic virus (PEMV), provided by L. Bos (Wageningen, the Netherlands) (1), using tissue blot immunoassay (2). Negatively stained preparations from chickpea and grasspea revealed typical PEMV-like isometric particles ≍30 nm in diameter. With immunoelectron microscopy, these particles were effectively trapped and strongly decorated with PEMV antibodies (immunoglobulin G diluted 1:10) provided by M. Musil (Bratislava, formerly Czechoslovakia) (4). The virus capsid protein was 22 kDa based on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, typical of the PEMV coat protein, and reacted strongly with PEMV antiserum (E154) in western blots. This is the first report of PEMV naturally infecting chickpea and grasspea in Syria and, to our knowledge, the first report in West Asia. PEMV reached epidemic levels on lentil in Syria for the first time in 1994 (3). Field symptoms observed in May 2001 suggest that PEMV may also seriously affect lentil, chickpea, and grasspea crops in Syria. References: (1) K. Mahmood and D. Peters. Neth. J. Plant Pathol. 79:138, 1973. (2) K. M. Makkouk and A. Comeau. Eur. J. Plant Pathol. 100:71, 1994. (3) K. M. Makkouk et al. Plant Dis. 83:303, 1999. (4) M. Musil et al. Acta Virol. 14:285, 1970.

First Record of Barley yellow striate mosaic virus and Cereal yellow dwarf virus-RPV Infecting Wheat in Uzbekistan.

A preliminary survey to identify virus diseases affecting wheat in Uzbekistan was conducted during May 2001. The survey covered 12 wheat fields from 2 cereal-growing regions (Tashkent-Angren and Tashkent-Samarkand). A total of 250 wheat samples with symptoms suggestive of virus infection were collected and tested for the presence of nine viruses by tissue-blot immunoassay (TBIA) (1) at the Virology Laboratory of ICARDA, Aleppo, Syria, using the following antisera: monoclonal antibodies for Cereal yellow dwarf virus-RPV (CYDV-RPV) (ATCC PVAS-669 [American Type Culture Collection, Manassas, VA]) and Barley yellow dwarf virus-MAV (BYDV-MAV) (ATCC PVAS-673); and polyclonal antibodies for BYDV-SGV and BYDV-RMV (3); BYDV-PAV, Barley stripe mosaic virus, and Wheat streak mosaic virus (from Virology Laboratory, ICARDA); Wheat dwarf virus (provided by J. Vacke, Research Institute of Crop Production, Prague, Czeck Republic); and Barley yellow striate mosaic virus (BYSMV) isolated from Lebanon (2). The most common virus present was BYDV-PAV (detected in 12% of the 250 samples tested), followed by BYDV-SGV (10.8%), BYSMV (5.6%), BYDV-RMV (2.4%), BYDV-MAV (2%), and CYDV-RPV (1.2%). CYDV-RPV was detected in three fields; one field was 50 km southeast of Tashkent, and the other two fields were between Tashkent and Samarkand. The majority of BYSMV-positive samples originated from the same field, ≈40 km northeast of Samarkand. Field symptoms of BYSMV-infected plants included yellow flag leaf and stunting. All samples that produced a positive reaction to BYSMV-Lebanon antiserum were tested against four other rhabdovirus antisera: BYSMV-Italy, BYSMV-Morocco, Cereal chlorotic mottle virus, and American wheat striate mosaic virus. Serological tests showed that 100% of the samples reacted strongly with BYSMV-Italy and BYSMV-Morocco. In sodium dodecyl sulfate-polyacrylamide gel electrophoresis, followed by western blots, extracts from BYSMV-infected plants were found to contain 66- and 47-kDa structural proteins, typical of G and N proteins of rhabdoviruses, both of which reacted strongly with BYSMV-Italy antiserum. To our knowledge, this is the first report of BYSMV and CYDV-RPV in Uzbekistan. References: (1) K. M. Makkouk and A. Comeau. Eur. J. Plant Pathol. 100:71, 1994. (2) K. M. Makkouk et al. Plant Dis. 85:446, 2001. (3) G. N. Webby and R. M. Lister. Plant Dis. 76:1125, 1992.

First Report of Barley yellow striate mosaic virus Infecting Barley and Wheat in Lebanon.

Symptoms suggestive of virus infection in barley, bread wheat, and durum wheat were observed at high incidence in November 2000 in Terbol, Beqa'a Valley, Lebanon. The symptoms were mainly stunting, accompanied by leaf striping and yellowing. Symptomatic plant samples (27 barley, 37 bread wheat, and 81 durum wheat) were collected and tested for the presence of four different viruses by tissue-blot immunoassay (TBIA) (1) at the Virology Laboratory of ICARDA, Aleppo, Syria. Antisera used were for Barley stripe mosaic virus (BSMV, genus Hordeivirus) (2); Barley yellow dwarf virus (BYDV, genus Luteovirus, family Luteoviridae) (PAV serotype) (2); Wheat streak mosaic virus (WSMV, genus Tritimovirus, family Potyviridae) (3); and Barley yellow striate mosaic virus (BYSMV, genus Cytorhabdovirus, family Rhabdoviridae) provided by M. Conti, Instituto di Fitovirologia applicata, Turino, Italy. BYSMV was detected in 12 barley, 18 bread wheat, and 56 durum wheat samples; the corresponding numbers of barley, bread wheat, and durum wheat plants testing positive for BYDV-PAV were 4, 7, and 6, respectively. BSMV and WSMV were not detected in any of the samples tested. BYSMV was purified from infected wheat plants, and the purified preparation had a UV 260:280 ratio of 1.18, typical of Rhabdoviruses. In SDS-polyacrylamide gel electrophoresis, the purified virus preparation indicated the presence of 66, 47, and 15 kDa structural proteins, typical of the G, N and M proteins of Rhabdoviruses. In western blot, the 66 and 47 kDa protein bands reacted strongly with BYSMV antiserum. This is the first record of BYSMV infecting barley and wheat in Lebanon. 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. 12:24, 1993. (3) K. M. Makkouk and S. G. Kumari. Rachis Newsl. 16:74, 1997.

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.

First Report of Soybean Dwarf Virus Infecting Lentil and Beet Western Yellows Virus Infecting Lentil and Chickpea Crops in Ethiopia.

A survey conducted during November 14-23, 1998, to identify viruses infecting chickpea (Cicer arietinum) and lentil (Lens culinaris) crops in the Shewa province of Ethiopia covered 33 chickpea and 32 lentil fields randomly selected. Identity of the viruses present and virus incidence were determined on the basis of laboratory testing of 100 to 200 randomly collected samples in addition to 15 to 20 symptomatic samples from each field. A total of 5,427 lentil and 3,836 chickpea samples were collected and tested for the presence of 12 different viruses by tissue blot immunoassay (1) at the Plant Pathology Laboratory in Debre Zeit Agriculture Research Center, Ethiopia. All antisera were virus specific, including those for beet western yellows virus (BWYV; ATCC PVAS-647) and soybean dwarf virus (SbDV; ATCC PVAS-650). More than 21% of the samples from 5 chickpea fields were infected; the most common virus was BWYV. Also, at least 21% of the samples from 11 lentil fields were virus positive; the most widespread virus was PSbMV. Highest rates of infection: of lentil in a single field, PSbMV in 58.5% of the samples; in a chickpea field, 41.3% of the samples positive for BWYV. Other viruses such as faba bean necrotic yellows nanovirus (FBNYV) and broad bean wilt fabavirus in chickpea and FBNYV, broad bean stain comovirus, bean yellow mosaic potyvirus, and cucumber mosaic cucumovirus in lentil were detected at very low incidence. Reference: (1) K. M. Makkouk and A. Comeau. Eur. J. Plant Pathol. 100:71, 1994.

Clustering Potyviridae species on the basis of four major traits.

Cluster analysis was used to examine taxonomic relationships among 31 potyviruses, using four categorical variables; genome segmentation, vector, inclusion bodies produced and host range. Analysis showed that regardless of weight given to genome segmentation, the fungus-transmitted viruses clustered in one group and the rest of the viruses in another at 60% level of similarity. It has been concluded that the creation of one family to include both the bymoviruses and potyviruses seems to be a reasonable compromise at the present time.