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Viruses - Lentil

Contributors to this page: ICARDA, Aleppo, Syria (Siham Asaad, Abdulrahman Moukahal).

Contents:
Bean yellow mosaic
Broad bean stain
Pea seed-borne mosaic
Broad bean mottle

Bean yellow mosaic

Scientific name

Bean yellow mosaic virus (BYMV)

Other scientific names

Bean virus 2 (BV-2), canna mosaic virus, gladiolus mosaic virus, gloriosa stripe mosaic virus

Significance

During our pulse surveys from 2000-2005, BYMV infections were uncommon and found in less than 1% of surveyed crops. However, BYMV was sometimes found in faba bean crops and occasionally in peas with within crop virus incidences of 1-15% and up to 7% respectively. In NSW, a small survey showed that faba bean crops had an average within crop incidence of BYMV of 26% of plants (ranging from 1-63%) (van Leur et al. 2002). Field surveys in 1998-1999 showed that some faba bean and field pea crops were infected with BYMV and the within crop virus incidences were 1-31% and 1-11% respectively. Plot trials showed that lupins infected with the necrotic strain of BYMV can have grain yields reduced by 95%.

Symptoms

Leaves of infected plants show mild mosaic followed by narrowing. New growth from leaf axils shows leaves that are narrow, elongated and light green. Early infections adversely affect plant growth and yield; there may be reduction in leaf size and stunting. Infected plants produce very little seed.

Bean yellow mosaic (photo: ICARDA)

Hosts

Wide host range. BYMV is reported to infect nearly 200 species in 14 families.

Legume hosts include lentils, chickpeas, beans, faba beans, green beans, peas, soybeans, peanuts, lupins, lathyrus, lucerne, vetch, clover, and various pasture hosts. The virus also infects horticultural and ornamental plants, such as gladiolus species.

Geographic distribution

Cosmopolitan

Biology and transmission

BYMV is transmitted by more than 50 aphid species in a non-persistent manner: the main species are Acyrthosiphon pisum, Aphis fabae, A. gossypii, Aulacorthum solani, Brevicoryne brassicae, Myzus persicae and Rhopalosiphum maidis. During our surveys in Victoria we have found the following BYMV vectors in pulse crops: Acyrthosiphon kondoi, Aphis craccivora, Aulacorthum solani, Brevicoryne brassicae and Myzus persicae. In WA Acyrthosiphon kondoi, Aphis craccivora, Myzus persicae, Brachycaudus rumexicolens, Lipaphis erysimi, Rhopalosiphum maidis, R. padi, Sitodion miscanthi and Therioaphis trifolii have been reported as BYMV vectors.
The virus is also transmitted through seed of most temperate pulses, including faba beans, field peas, lentils, and lupins and through seed of a number of forage legumes and clovers. In Victoria, we found 18% of lentil seed lots tested had BYMV infections of 0.1-0.9%. In WA, the following BYMV seed transmission is reported: yellow and white lupins 3-6%, field peas 0.3-0.8%, faba beans 0.4%, lathyrus 0.1-0.2% and vetch 0.5%.
Seed transmission of BYMV in medics and clovers has also been reported in WA as follows: Melilotus indica (0.5%), Medicago polymorpha (0.9%), M. truncatula (0.3%), M. indica (1%), Trifolium arvense (0.1%), T. campestre (0.2%) and T. glomeratum (0.05%).

Detection/indexing methods used at ICARDA

Treatment/control

Procedures followed in case of positive test at ICARDA

References and further reading

Aftab M, Freeman A. 2006. Temperate pulse viruses: Bean yellow mosaic virus (BYMV). Agriculture note AG1266. Melbourne: Department of Primary Industries, Victoria, Australia.

Beniwal SPS, Baya’a B, Weigand S, Makkouk KH, Saxena MC. 1993. Bean yellow mosaic. In Field Guide to Lentil Diseases and Insect Pests. Aleppo: ICARDA. [online] Available from URL: http://www.icarda.org/Publications/Field_Guides/Lentil/Lentil.htm#Lent7.html. Date accessed 13 April 2010

Bean yellow mosaic virus (BYMV) (photos: Department of Primary Industries, Victoria, Australia)

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Broad bean stain

Scientific name

Broad bean stain virus (BBSV)

Other scientific names

Broad bean F1 virus, broad bean Evesham stain virus

Significance

In a study of 19 lentil genotypes in Syria, yield loss due to infection varied between 14% and 61% (Makkouk and Kumari 1990).

Symptoms

The disease is characterized by a mild mottling on the leaves, although this is not easy to recognize due to the small size of lentil leaf.

Affected plants are reduced in growth, which is easily recognized, especially in comparison with healthy plants. Yield of affected plants is also reduced.

Seed from infected plants occasionally show dark staining.

Healthy lentil seed (right) and seed with BBSV symptoms (left) which include dark staining and distortion.(photo: PaDIL, ICARDA).

Hosts

The virus is restricted to legumes. In addition to lentil, it also naturally affects faba bean (or broad bean), dry pea and vetch.

Geographic distribution

Europe, Middle East, North Africa, West Asia

Biology and transmission

BBSV is transmitted by insect vectors, the weevilsApion vorax and Sitona spp. It is also transmitted through sap and seed. In 19 lentil genotypes studied in Syria seed transmission rates varied between 0.2% and 32.4% (Makkouk and Kumari 1990).

Detection/indexing methods used at ICARDA

Treatment/control

Procedures followed in case of positive test at ICARDA

References and further reading

Beniwal SPS, Baya’a B, Weigand S, Makkouk KH, Saxena MC. 1993. Broad bean stain. In Field Guide to Lentil Diseases and Insect Pests. Aleppo: ICARDA. [online] Available from URL: http://www.icarda.org/Publications/Field_Guides/Lentil/Lent7.Html#_Broad. Date accessed 13 April 2010

Gibbs AJ, Smith HG. 1970. Broad bean stain virus. Descriptions of plant viruses 29. Association of Applied Biologists. [online] Available from URL: http://www.dpvweb.net/dpv/showdpv.php?dpvno=029. Date accessed 13 April 2010

Makkouk KM, Kumari SG. 1990. Variability among 19 lentil genotypes in seed transmission rates and yield loss induced by broad bean stain virus infection. LENS Newsletter 17(2): 31-33.

Plants and Diseases Image Library (PaDIL). Plant biosecurity toolbox: Broad bean stain virus (BBSV). [online] Available from URL: http://www.padil.gov.au/pbt/index.php?q=node/20&pbtID=154. Date accessed 13 April 2010

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Pea seed-borne mosaic

Scientific Name

Pea Seed-borne Mosaic Virus (PSbMV)

Other scientific names

Pea fizzle top virus, pea leaf rolling virus, pea leaf roll mosaic virus, pea leaf rolling mosaic virus.

Significance

PSBMV is of economic importance in pea, faba bean and lathyrus, mainly due to its effect on seed quality. It has been mistakenly considered to be a minor disease because it often causes only minor yield loss and mild symptoms, However, at the International Centre for Agriculture in the Dry Areas (ICARDA), Syria, glasshouse studies on yield losses due to PSBMV in chickpea, faba bean, lentil and pea showed losses of 66%, 40.5%, 44.6% and 49.2% respectively. In SA, glasshouse experiments showed that pathotypes P1 and P4 could reduce seed yield by 35% and 82% respectively. Surveys of pulse crops over a number of years in Vic and SA showed that up to 15% of crops were infected with PSBMV, with a within crop incidence of up to 5% of plants. In surveys in WA in 1999, PSBMV was found in 42% of field pea crops and the level of virus detected in pea seed stocks was up to 63%. The surveys in WA indicated that PSBMV has a severe effect on seed quality of pulse crops with seed coat symptoms evident on >80% of faba bean, >50% of lathyrus species and field peas and 5% of chickpea seed. At NSW-DPI Tamworth, screening of pea germplasm in the field for resistance to PSBMV has shown that highly susceptible lines may be 100% infected late in the season (Van Leur, unpublished).

Symptoms

The disease is characterized by a mild mottling on the leaves, which is not easily recognizable because of the small size of the lentil leaf.

The affected plants are reduced in growth, which is easily recognized, especially when they are compared with healthy plants. Yield reductions of 15-16% could occur in some different cultivars. Seeds from infected plants occasionally show dark staining on the seed.

Lentils may show no symptoms or there may be chlorosis in new shoots, mottling on leaves, shoot tip necrosis and stunting of plants.

Hosts

The natural host range of PSBMV is limited to the Fabaceae. It infects temperate pulses (chickpea, faba bean, field pea, lentil) other legumes (garden pea, narbon bean) and pastures (lathyrus and vetch). A number of PSBMV pathotypes have been recognised by their ability to infect a number of pea differential genotypes.

Geographic distribution

Worldwide

Biology and transmission

The virus is believed to have spread worldwide through the exchange of infected seed. Seed transmission rates of up to 100% in peas and up to 44% in lentils have been reported. In Victoria, we have detected PSBMV at low levels in some commercial chickpea seedlots (0.4% of seed) and at higher levels in field pea and lentil seedlots (greater than 2% of seed). In the USA, 3% PSBMV infection in pea seedlots and 32-40% in lentil seedlots have been reported. At ICARDA, PSBMV was found to be transmitted through lentil seeds at rates of up to 44%. PSBMV is also transmitted in a non-persistent manner by more than 20 aphid species and by mechanical means. The most efficient vector is the pea aphid (Acyrthosiphon pisum). The other species are as follows: A. pelargoni, A. sesbaniae, Aphis craccivora, A. fabae, A. gossypii, A. nasturtii, Aulacorthum circumflexum, A. solani, Brevicoryne brassicae, Cryptomyzus ribis, Dactynotus escalantii, Macrosiphum avenae, M. euphorbiae, M. pisi, M. rosae, Metopolophium dirhodum, Myzus persicae, Ovatus crataegarius, Phorodon cannabis, Rhopalosiphum padi and Semiaphis dauci. In Victorian pulse crop surveys, we have found cowpea aphid (Aphis craccivora), foxglove aphid (Aulacorthum solani), and green peach aphid (Myzus persicae), which are all vectors of PSBMV.

Detection/indexing method in place at the CGIAR Center at ICARDA

Treatment/control

Procedure followed at the centers in case of positive test

References and further reading

http://www.icarda.org/Publications/Field_Guides/Lentil/Lent7.Html

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Broad bean mottle

Scientific Name

Broad bean Mottle Virus (BBMV)

Significance

The virus was seen as being of minor importance until reports of its widespread occurrence began to appear in the 1970s and 1980s.

Symptoms

Three quarters of the plants displayed leaf symptoms, many were dwarfed and produced few or no flowers. Infected plants were in concentric patches, BBMV can affect seed quality by causing necrosis and shrivelling of the seed. Seed transmission rates in legumes are low and range from 0.1% to 1.4%.

Hosts

Under experimental conditions susceptibility to infection by virus is found in several families. Susceptible host species are found in the Family Amaranthaceae, Chenopodiaceae, Leguminosae-Papilionoideae, Solanaceae. The following species were susceptible to experimental virus infection: Chenopodium album, Chenopodium amaranticolor, Chenopodium hybridum, Chenopodium quinoa, Cyamopsis tetragonoloba, Glycine max, Gomphrena globosa, Lathyrus odoratus, Lens culinaris, Lupinus albus, Medicago sativa, Melilotus albus, Nicotiana clevelandii, Phaseolus vulgaris, Pisum sativum, Trifolium hybridum, Trifolium incarnatum, Trifolium pratense, Trifolium repens, Trifolium subterraneum, Vicia faba, Vicia villosa.

Geographic distribution

BBMV was reported in faba bean crops in Portugal, Sudan, Morocco, and Algeria. then undertook a regional survey and found BBMV in faba bean crops in Egypt, Morocco, Sudan, Syria and Tunisia. Fortass and Bos (1991) surveyed faba bean crops in Morocco and found that luteoviruses and BBMV were the most prevalent viruses.

Biology and transmission

BBMV survives between growing seasons of the primary pulse host in an alternative host or in infected seed. Due to the fact that the natural host range includes at least four families and includes many food legumes and non-legume wild hosts, it may survive in a range of alternative hosts.

Virus is transmitted by a vector. Virus is transmitted by mechanical inoculation; transmitted by grafting.

Virus is transmitted by arthropods, by insects of the order Coleoptera; Acalymma trivittata, Colaspis flavida, Diabrotica undecimpunctata, Sitona lineata.

Detection/indexing method in place at the CGIAR Center at ICARDA

Treatment/control

Procedure followed at the centers in case of positive test

References and further reading

http://www.padil.gov.au/pbt/index.php?q=node/46&pbtID=152

http://www.ncbi.nlm.nih.gov/ICTVdb/ICTVdB/00.010.0.03.002.htm

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The Genebanks

The 11 CGIAR genebanks currently conserve 730,000 of cereals and grain legumes, forage crops, tree species, root and tuber crops, bananas and crop wild relatives.

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