Distribution and incidence of necrotic and non-necrotic strains of bean yellow mosaic virus in wild and crop lupins

A new strain of bean yellow mosaic virus (BYMV), a non-necrotic strain, was found in south-west Western Australia. It differs from the original necrotic strain of BYMV in that it does not kill Lupinus angustifolius (narrow-leafed lupin) plants, but causes symptoms of mottle and stunting, or dead growing points, fleshy expanded leaves, and stunting. A survey of L. angustifolius crops during September and October 1997 compared the distribution and incidence of the necrotic strain with that of the non-necrotic strain. Based on 1000 plants inspected at the edge of each crop, the necrotic strain was found in 100 of 102 crops while the non-necrotic strain was found in 64 of them. Incidences ranged from 0.3 to 56% (necrotic strain) and 0.1 to 7% (non-necrotic strain) of plants counted. Both strains were present over the whole range of the survey. Wild L. angustifolius and L. luteus (yellow lupin) populations were also inspected. The necrotic and non-necrotic strains were found in 31 and 9 of the 34 L. angustifolius populations examined, respectively. Incidences ranged from 0.1 to 28% (necrotic strain) and 0.1 to 3% (non-necrotic strain) of plants counted. BYMV was found in 9 of 11 wild L. luteus populations with incidences ranging from 0.3 to 7% of plants counted. In a separate survey in which samples of L. angustifolius crops, with necrotic symptoms suspected of being caused by Colletotrichum gloeosporioides (lupin anthracnose disease), were examined, 37 of 130 samples had typical necrotic BYMV symptoms. Samples with these necrotic symptoms also came from northern and eastern wheatbelt areas not normally associated with BYMV infection. When 8 BYMV isolates cultured by sap inoculation in Trifolium subterraneum (subterranean clover) were tested by aphid transmission to L. angustifolius plants in 1994 and again in 1997, the isolates of the 2 strains behaved the same on both occasions causing only necrotic (3 isolates) or non-necrotic (5 isolates) symptoms. Thus, despite repeated subculture by sap inoculation over a 3.5-year period, the 2 BYMV strains still remained distinct. An isolate collected from wild L. luteus in 1997 produced only non-necrotic symptoms in L. angustifolius. The non-necrotic strain caused symptoms typical of BYMV in hosts other than L. angustifolius, reacted strongly with BYMV antiserum, and failed to react with antiserum to clover yellow vein virus. In a BYMV-infected lupin crop, grain yields of individual L. angustifolius plants infected early with the non-necrotic strain were decreased by 95%. Shoot weights, seed number, and seed size were also greatly decreased. Widespread occurrence of the non-necrotic strain of BYMV is cause for concern for the lupin industry.

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Occurrence of bean yellow mosaic virus in subterranean clover pastures and perennial native legumes

Australian Journal of Agricultural Research ◽

10.1071/ar9940183 ◽

1994 ◽

Vol 45 (1) ◽

pp. 183 ◽

Cited By ~ 30

Author(s):

SJ McKirdy ◽

BA Coutts ◽

RAC Jones

Keyword(s):

Mosaic Virus ◽

Western Australia ◽

White Clover ◽

Subterranean Clover ◽

Trifolium Subterraneum ◽

Bean Yellow Mosaic Virus ◽

Yellow Vein ◽

Yellow Mosaic Virus ◽

South West ◽

Clover Yellow Vein Virus

In 1990, infection with bean yellow mosaic virus (BYMV) was widespread in subterranean clover (Trifolium subterraneum) pastures in the south-west of Western Australia. When 100 leaves were sampled at random per pasture, the virus was detected by ELISA in 23 of 87 pastures and incidences of infection ranged from 1 to 64%. BYMV was present in all seven districts surveyed, but highest incidences of infection occurred in the Busselton district. In smaller surveys in 1989 and 1992, incidences of infection in pastures were higher than in 1990, and ranged up to 90%. In 1992, when petals from 1703 samples of 59 species of perennial native legumes from 117 sites were tested by ELISA, only 1% were found infected with BYMV. The infected samples came from 5/7 districts surveyed. Species found infected were Kennedia prostrata, K. coccinea, Hovea elliptica and H. pungens. Representative isolates of BYMV from subterranean clover and native legumes did not infect white clover systemically confirming that clover yellow vein virus (CYVV) was not involved. It was concluded that BYMV infection was present in many subterranean clover pastures, but normally at low incidences, except in epidemic years such as 1992. Also, perennial native legumes are unlikely to act as major reservoirs for reinfection of annual pastures each year. In areas of Australia with Mediterranean climates where perennial pastures are absent, persistence of the virus over summer is therefore by some other method than infection of perennials.

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Production of Bean yellow mosaic virus resistant subterranean clover (Trifolium subterraneum) plants by transformation with the virus coat protein gene

Annals of Applied Biology ◽

10.1111/j.1744-7348.1999.tb00876.x ◽

1999 ◽

Vol 135 (2) ◽

pp. 469-480 ◽

Cited By ~ 9

Author(s):

P. W. G. CHU ◽

B. J. ANDERSON ◽

M. R. I. KHAN ◽

D. SHUKLA ◽

T. J. V. HIGGINS

Keyword(s):

Coat Protein ◽

Mosaic Virus ◽

Coat Protein Gene ◽

Protein Gene ◽

Subterranean Clover ◽

Trifolium Subterraneum ◽

Bean Yellow Mosaic Virus ◽

Yellow Mosaic Virus ◽

Virus Coat Protein ◽

Virus Coat

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Genetic improvement of subterranean clover (Trifolium subterraneum L.). 2. Breeding for disease and pest resistance

Crop and Pasture Science ◽

10.1071/cp14031 ◽

2014 ◽

Vol 65 (11) ◽

pp. 1207 ◽

Cited By ~ 20

Author(s):

P. G. H. Nichols ◽

R. A. C. Jones ◽

T. J. Ridsdill-Smith ◽

M. J. Barbetti

Keyword(s):

Plant Breeding ◽

Mosaic Virus ◽

Pest Resistance ◽

Subterranean Clover ◽

Trifolium Subterraneum ◽

Yellow Mosaic Virus ◽

Genotypic Differences ◽

Pythium Irregulare ◽

Halotydeus Destructor ◽

Subterranean Clover Stunt Virus

Subterranean clover (Trifolium subterraneum L.) is the most widely sown pasture legume in southern Australia and resistance to important diseases and pests has been a major plant-breeding objective. Kabatiella caulivora, the cause of clover scorch, is the most important foliar fungal pathogen, and several cultivars have been developed with resistance to both known races. Screening of advanced breeding lines has been conducted to prevent release of cultivars with high susceptibility to other important fungal foliar disease pathogens, including rust (Uromyces trifolii-repentis), powdery mildew (Oidium sp.), cercospora (Cercospora zebrina) and common leaf spot (Pseudopeziza trifolii). Several oomycete and fungal species cause root rots of subterranean clover, including Phytophthora clandestina, Pythium irregulare, Aphanomyces trifolii, Fusarium avenaceum and Rhizoctonia solani. Most breeding efforts have been devoted to resistance to P. clandestina, but the existence of different races has confounded selection. The most economically important virus diseases in subterranean clover pastures are Subterranean clover mottle virus and Bean yellow mosaic virus, while Subterranean clover stunt virus, Subterranean clover red leaf virus (local synonym for Soybean dwarf virus), Cucumber mosaic virus, Alfalfa mosaic virus, Clover yellow vein virus, Beet western yellows virus and Bean leaf roll virus also cause losses. Genotypic differences for resistance have been found to several of these fungal, oomycete and viral pathogens, highlighting the potential to develop cultivars with improved resistance. The most important pests of subterranean clover are redlegged earth mite (RLEM) (Halotydeus destructor), blue oat mite (Penthaleus major), blue-green aphid (Acyrthosiphon kondoi) and lucerne flea (Sminthurus viridis). New cultivars have been bred with increased RLEM cotyledon resistance, but limited selection has been conducted for resistance to other pests. Screening for disease and pest resistance has largely ceased, but recent molecular biology advances in subterranean clover provide a new platform for development of future cultivars with multiple resistances to important diseases and pests. However, this can only be realised if skills in pasture plant pathology, entomology, pre-breeding and plant breeding are maintained and adequately resourced. In particular, supporting phenotypic disease and pest resistance studies and understanding their significance is critical to enable molecular technology investments achieve practical outcomes and deliver subterranean clover cultivars with sufficient pathogen and pest resistance to ensure productive pastures across southern Australia.

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