Infection of alternative hosts associated with annual medics (Medicago spp.) by alfalfa mosaic virus and its persistence between growing seasons

1994 ◽  
Vol 45 (7) ◽  
pp. 1413 ◽  
Author(s):  
SJ McKirdy ◽  
RAC Jones
Keyword(s):  
Mosaic Virus ◽  
Alfalfa Mosaic Virus ◽  
Trifolium Subterraneum ◽  
Seed Transmission ◽  
Herbaceous Plant ◽  
Alternative Hosts ◽  
Growing Seasons ◽  
Alternative Means ◽  
Annual Medics ◽  
Annual Medicago

Under conditions of natural alfalfa mosaic virus (AMV) spread, five plant species found associated with annual Medicago spp. (medics) were infected commonly and another seven sporadically. Ten of these were new records. Because seed of herbaceous plant hosts provides a possible route for virus persistence through dry summer conditions, AMV seed transmission was tested for in alternative hosts. Of ten species systemically infected by sap inoculation with AMV, seed transmission was detected in Melilotus indica (l0%), Ornithopus compressus (0 1%) and Stachys arvensis (2%). Seed of seven naturally infected potential alternative host species was tested, and seed transmission found in Crassula decumbens (0. 1%), M. indica (3%), 0. compressus (0.2%), S. arvensis (0.4%) and Trifolium subterraneum (2%). Carry-over of AMV through seed transmission was detected in seedlings of Hypochaeris glabra (0.2%) and M. indica (0.6-0.8%) that germinated naturally in the field. In grazed, self-regenerated Medicago murex and M. polymorpha swards sown in 1987, the virus persisted for at least seven growing seasons. Levels of infection in M. polymorpha seed produced each year declined, but levels in the general seed bank remained higher due to presence of older seed. It is concluded that under the conditions of broadacre agriculture in the Mediterranean-type climate of Western Australia, seed transmission in C. decumbens, H. glabra and volunteer 0. compressus is an alternative means by which AMV can persist over summer to act as sources of AMV for spread within annual medic pastures. However, persistence through seed of the annual medic cultivars sown and of naturalized annual Medicago species is the principal means of persistence. AMV persists readily from year to year following sowing of infected seed and is likely to cause a recurrent disease problem in annual medic pastures.

Factors influencing transmission of alfalfa mosaic virus through seed of annual medics (Medicago spp.) and the genetic control of seed transmission rate

1997 ◽  
Vol 48 (7) ◽  
pp. 989 ◽  
Author(s):  
W. Pathipanawat ◽  
R. A. C. Jones ◽  
K. Sivasithamparam
Keyword(s):  
Mosaic Virus ◽  
Genetic Control ◽  
Transmission Rate ◽  
Alfalfa Mosaic Virus ◽  
Seed Transmission ◽  
Virus Concentration ◽  
Rate Condition ◽  
Reciprocal Crosses ◽  
Transmission Rates ◽  
Annual Medics

Factors likely to influence rates of transmission of alfalfa mosaic virus (AMV) through seed to seedlings of annual medics (Medicago spp.) and genetic control of the magnitude of its seed transmission rate were investigated in plants from 17 early-flowering accessions of M. polymorpha and in progenies of crosses involving M. murex cv. Zodiac × accession 5320 as parents. Plants were graft-inoculated when 6 weeks old to ensure successful and uniform infection. To exclude variation in seed transmission rates due to virus isolate or temperature, only 1 AMV isolate was used and the plants were kept under uniform temperature conditions. In M. polymorpha, significant differences were found between accessions in the levels of AMV transmitted through seed to progeny seedlings, SA 8250 giving the highest mean level of seed transmission (52%) and SA 4188 the lowest (3%). Neither virus concentration nor symptom severity influenced the rates of seed transmission obtained. However, part of the variation in seed transmission rates found in these accessions was related to their flowering times, seed transmission rates increasing as the interval between inoculation and owering increased. In seed samples collected from individual graft-inoculated plants of M. murex from (i) the F2 generation from crosses and reciprocal crosses, and (ii) the backcross progenies, the rates of transmission of AMV through seed to seedlings ranged from 0 to 77% and showed a continuous pattern of variation. Also, there was evidence of transgressive segregation for the low seed transmission rate condition. This indicates that the low seed transmission rate condition for AMV in medics is quantitatively inherited and under polygenic control. In contrast, when the pods from F2 progeny plants from the crosses and reciprocal crosses were examined, the segregation ratios obtained revealed that the smooth pod character from parent accession 5320 was controlled by a single recessive gene, for which the name sp is proposed. The presence in a plant of gene sp, or of its spiny pod-determining allele from the other parent cv. Zodiac, was not correlated with low seed transmission rates of AMV. It is concluded that selection for low rates of seed transmission and a population breeding approach can be used to produce improved M. polymorpha and M. murex cultivars with good resistance to seed-borne AMV

Infection of alternative hosts associated with narrow-leafed lupin (Lupinus angustifolius) and subterranean clover (Trifolium subterraneum) by cucumber mosaic virus and its persistence between growing seasons

1994 ◽  
Vol 45 (5) ◽  
pp. 1035 ◽  
Author(s):  
SJ McKirdy ◽  
RAC Jones
Keyword(s):  
Cucumber Mosaic Virus ◽  
Mosaic Virus ◽  
Host Species ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Seed Transmission ◽  
Lupinus Angustifolius ◽  
Minor Role ◽  
Alternative Hosts ◽  
A Minor

Under conditions of natural cucumber mosaic virus (CMV) spread, eight alternate host species found associated with Lupinus angustifolius (narrow-leafed lupin) and/or Trifolium subterraneum (subterranean clover) were infected commonly and another nine sporadically. Five of these were new records. Because seed of herbaceous plant hosts provides a possible route for virus persistence through dry summer conditions, CMV seed transmission was tested for in alternative hosts. Seed of seven species systemically infected following sap inoculation was tested, but CMV seed transmission was only detected in M. polymorpha (0.7%) and M. indica (0.1%). When seed of 14 potential alternative host species that became systemically infected through natural virus spread was tested, CMV seed transmission was found only in C. decumbens (0.5%). No CMV was detected in Citrullus lanatus growing as a deep-rooted, herbaceous summer weed following CMV-infected L. angustifolius crops, or in the perennial Acacia saligna growing adjacent to a previously CMV-infected L. angustifolius field. CMV persisted through seed transmission over summer for up to 5 years in grazed, self-regenerated T. subterraneum swards. It is concluded that under the conditions of broadacre agriculture, in the Mediterranean-type climate of Western Australia, weed hosts are unlikely to be an important means by which CMV persists over summer, but seed transmission in naturalized M. polymorpha and C. decumbens may occassionally play a minor role. Moreover, despite being seed-borne in T. subterraneum, CMV did not persist readily enough from year to year in grazed swards for T. subterraneum pastures to play more than a minor role as a CMV source for infection of L. angustifolius .

Subterranean clover mottle virus infection of subterranean clover: widespread occurrence in pastures and effects on productivity

1992 ◽  
Vol 43 (7) ◽  
pp. 1597 ◽  
Author(s):  
JM Wroth ◽  
RAC Jones
Keyword(s):  
Systemic Infection ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Seed Transmission ◽  
Dry Weight ◽  
Widespread Occurrence ◽  
Transmission Rates ◽  
Type Isolate ◽  
Growing Seasons ◽  
South West

In 1989 and 1990, infection with subterranean clover mottle sobemovirus (SCMV) was widespread in subterranean clover ( Trifolium subterraneum L.) pastures in the south-west of Western Australia. The virus was detected in 61% of the pastures sampled and incidences of infection ranged from 1 to 50%. The virus was more common in old pastures than in pastures resown with newer cultivars during the preceeding 5 year period. When 12 isolates of SCMV were inoculated to subterranean clover plants grown in the glasshouse, symptoms varied from mild to severe. SCMV isolates P23 and F4 decreased the herbage dry weight of cw. Daliak and Woogenellup grown in plots as spaced plants by 81-88% while the Type isolate caused losses of 92%. By contrast, losses were 37-49% with cv. Karridale, a cultivar in which systemic infection was either delayed or prevented during winter. Infection decreased seed yield by c. 90% in cvv. Karridale and Woogenellup with all three isolates; seed weight was decreased 21-55%. A small proportion of cv. Woogenellup transplants outgrew the infection in new shoots during late spring to produce abundant healthy foliage. SCMV seed transmission rates in seed collected from infected transplants of cv. Woogenellup were 0.06, 0.07 and 0.43% for the Type, P23 and F4 isolates respectively. It was concluded that SCMV was present in most pastures, but at low incidences, and that it persists in them from year to year. Extended growing seasons and hard grazing are likely to increase its incidence.

scholarly journals Cucumber green mottle mosaic virus.

2021 ◽  
Author(s):  
Craig Webster ◽  
Roger Jones
Keyword(s):  
South America ◽  
Mosaic Virus ◽  
Plant Material ◽  
High Stability ◽  
Seed Transmission ◽  
Crop Species ◽  
Growing Seasons ◽  
Contact Transmission ◽  
Vegetables And Fruits

Abstract CGMMV is a species of virus in the genus Tobamovirus, which was first described in 1935 in England. Between 1935 and 1985 it spread slowly to other countries, but faster between 1986 and 2006, and rapidly between 2007 and 2018. It now occurs on all continents except South America. In cucurbits, it causes a damaging disease that reduces fruit yields and quality and spreads efficiently by plant-to-plant contact transmission. Outbreaks occur in many cucurbit crops including vegetables and fruits (e.g. squash and melons). CGMMV seed transmission occurs in at least nine different cucurbit crop species and this is the main way the virus has spread worldwide. Importation of contaminated seeds constitutes a considerable biosecurity concern for counties still without CGMMV. Its high stability and its persistence in contaminated plant material and soil allow it to survive between growing seasons, making eradication difficult.

Bean leafroll virus is widespread in subterranean clover (Trifolium subterraneum L.) seed crops and can be persistently transmitted by bluegreen aphid (Acyrthosiphon kondoi Shinji)

2012 ◽  
Vol 63 (9) ◽  
pp. 902 ◽  
Author(s):  
D. M. Peck ◽  
N. Habili ◽  
R. M. Nair ◽  
J. W. Randles ◽  
C. T. de Koning ◽  
...  
Keyword(s):  
Cucumber Mosaic Virus ◽  
Mosaic Virus ◽  
Seed Production ◽  
Alfalfa Mosaic Virus ◽  
South Australia ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Bean Leafroll Virus ◽  
Leafroll Virus ◽  
Clover Seed

In the mid 2000s subterranean clover (Trifolium subterraneum) seed producers in South Australia reported symptoms of a red-leaf disease in fields with reduced seed yields. The red-leaf symptoms resembled those caused by several clover-infecting viruses. A set of molecular diagnostic tools were developed for the following viruses which are known to infect subterranean clover: Alfalfa mosaic virus; Bean leafroll virus (BLRV); Beet western yellows virus; Bean yellow mosaic virus; Cucumber mosaic virus; Pea seed-borne mosaic virus; Soybean dwarf virus and Subterranean clover stunt virus. Surveys of subterranean clover seed production fields in 2008 in the south-east of South Australia and western Victoria identified Bean leafroll virus, Alfalfa mosaic virus and Cucumber mosaic virus as present, with BLRV the most widespread. Surveys of pasture seed production fields and pasture evaluation trials in 2009 confirmed that BLRV was widespread. This result will allow seed producers to determine whether control measures directed against BLRV will overcome their seed losses. Bluegreen aphid (Acyrthosiphon kondoi) was implicated as a potential vector of BLRV because it was observed to be colonising lucerne plants adjacent to subterranean clover seed production paddocks with BLRV, and in a glasshouse trial it transmitted BLRV from an infected lucerne plant to subterranean clover in a persistent manner.

Occurrence of alfalfa mosaic and subterranean clover red leaf viruses in legume pastures in Western Australia

1995 ◽  
Vol 46 (4) ◽  
pp. 763 ◽  
Author(s):  
SJ McKirdy ◽  
RAC Jones
Keyword(s):  
Western Australia ◽  
Alfalfa Mosaic Virus ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Seed Transmission ◽  
Enzyme Linked Immunosorbent Assay ◽  
The South ◽  
Potential Threat ◽  
South West ◽  
Burr Medic

When leaf samples were collected from 94 Trifolium subterraneum (subterranean clover) pastures from six districts in spring 1993 in the south-west of Western Australia and tested by enzyme-linked immunosorbent assay, no alfalfa mosaic virus (AMV) or subterranean clover red leaf virus (SCRLV) was detected. In contrast, when 21 irrigated T. repens (white clover) pastures from one district (Bunbury) were sampled and tested in January (summer) 1994, AMV was detected in 16, with eight having infection levels >86%, while SCRLV was found in seven at infection levels of <12%. When a further five T. repens pastures were tested for AMV in October (spring) 1994, the virus was found in all with incidences up to 100%. None of the T. repens pastures with high levels of AMV infection had been resown with T. repens within the last 20 years, whereas those resown within the last five years had little or no infection. AMV was detected in 9/91 annual medic (Medicago spp.) pastures from seven wheatbelt districts sampled in spring 1991 or 1993; a single pasture of M. polymorpha (burr medic) cv. Serena was 21% infected, but the other eight infected ones had <3%. AMV seed transmission was detected in 1/19 commercial seed stocks of M. polymorpha harvested in 1991-93. AMV infection was followed over a 12-year period in M. murex (murex medic) cv. Zodiac seed stocks. It persisted readily through successive seed harvests during this period. It is concluded that infection with AMV and SCRLV is currently not a threat to T. subterraneum pastures in the south-west of Western Australia and that AMV seems not to be one in wheatbelt annual medic pastures provided these are sown with healthy medic seed. In contrast, AMV poses a potential threat to the productivity of irrigated T. repens pastures. SCRLV is also sometimes present in T. repens pastures, but was not found at serious levels.

An epidemic of cucumber mosaic virus in South Australian lupins

1985 ◽  
Vol 36 (2) ◽  
pp. 267 ◽  
Author(s):  
E Alberts ◽  
J Hannay ◽  
JW Randles
Keyword(s):  
Cucumber Mosaic Virus ◽  
Mosaic Virus ◽  
Vicia Faba ◽  
Transmission Rate ◽  
South Australia ◽  
Trifolium Subterraneum ◽  
Seed Transmission ◽  
Severe Stunting ◽  
Experimental Host Range

Many Lupinus angustifolius crops in South Australia showed a high incidence of severe stunting and leaf epinasty during 1983. The epidemic was attributed to infection with cucumber mosaic virus. The virus was also recovered from Trifolium subterraneum cv. Geraldton, Medicago polymorpha, Vicia faba, Erodium sp. and Arctotheca calendula growing in or adjacent to lupin crops. The experimental host range of the virus included T. subterraneum cv. Clare, T. repens, Pisurn sativum, Vicia faba and Cicer arietinum. A seed transmission rate of 12-15% was demonstrated in field-infected lupins, and it is concluded that the epidemic probably arose through primary introduction of virus into crops in seed, followed by secondary spread by aphids. The possible role of alternative host species as a reservoir is discussed.

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