Studies on alfalfa mosaic virus infection of burr medic (Medicago polymorpha) swards: seed-borne infection, persistence, spread and effects on productivity

1992 ◽  
Vol 43 (3) ◽  
pp. 697 ◽  
Author(s):  
RAC Jones ◽  
DA Nicholas
Keyword(s):  
Mosaic Virus ◽  
Seed Yield ◽  
Alfalfa Mosaic Virus ◽  
Primary Source ◽  
Medicago Polymorpha ◽  
Daily Growth ◽  
Infected Seed ◽  
Burr Medic ◽  
Seed Yields ◽  
Healthy Seed

During 1988-90, burr medic (Medicago polymorpha) cvv. Circle Valley, Serena and/or Santiago were grown in field trials in which plots were sown with healthy seed or seed that carried varying levels of infection with alfalfa mosaic virus (AMV). Seed-infected plants were the primary source for subsequent virus spread by aphids. Levels of AMV infection normally reached 80-100% in swards sown with infected seed whether they were mown, grazed or not defoliated, most spread occurring late in the growing season. Infection of harvested seed was often less than in seed sown. However, in self-regenerated grazed swards AMV spread earlier and infection in harvested seed was up to 10 times greater than in seed before regeneration. In two trials sown in 1988, plots were mown or left uncut; AMV infection decreased herbage yields by 13-35% while seed yields were decreased significantly (by 7-30%) in one of the two trails. When one of these trials was cropped with barley in 1989 but allowed to regenerate in 1990 and grazed, herbage yield fell by 5-15% and seed yield by 2-29% due to AMV infection. In a trial sown in 1989 in which some plots were grazed and others not, AMV infection decreased herbage and seed yields by 27-32% and 21-29% respectively. In a similar grazing trial sown in 1990, AMV infection decreased herbage daily growth rates by 16-42% and seed yield sometimes by as much as 32%. Seed harvested from plots sown with infected seed was normally smaller than seed from plots sown with healthy seed. AMV-infected swards were established in 1987, allowed to regenerate in 1988-91 and grazed. With cvv. Circle Valley and Serena, AMV was readily detected each year in foliage and was also found in seeds.

Further studies on losses in productivity caused by infection of annual pasture legumes with three viruses

1992 ◽  
Vol 43 (5) ◽  
pp. 1229 ◽  
Author(s):  
RAC Jones
Keyword(s):  
Mosaic Virus ◽  
Seed Size ◽  
Seed Yield ◽  
Alfalfa Mosaic Virus ◽  
Subterranean Clover ◽  
Yellow Mosaic Virus ◽  
Root Production ◽  
Pasture Legumes ◽  
Burr Medic ◽  
Severe Isolate

Trials were done in 1988-90 to examine the effects of infection with three non persistently aphid-transmitted viruses on the productivity of manually inoculated spaced plants of annual pasture legumes growing in plots. Alfalfa mosaic virus (AMV) decreased herbage and root production (dry weights) of three subterranean clover (Trifolium subterraneum L.) cultivars by 20-49%. Cucumber mosaic virus (CMV) decreased herbage and root production of a murex medic (Medicago murex Wild.) cultivar by 78-90% and of two burr medic (M. polymorpha L.) cultivars by 56-82%. A mild isolate of bean yellow mosaic virus (BYMV) decreased herbage and root production of a subterranean clover cultivar by 31-40%, but with a severe isolate the corresponding losses were 60-63010 in the same cultivar and 79-80% in another. The severe BYMV isolate caused losses in herbage and root production of 38-61% in two burr medic cultivars. Seed yield losses recorded due to infection of subterranean clover were 71% with AMV and 58-76% with BYMV (severe isolate); both viruses decreased seed size as well as seed yield. CMV decreased seed yield by 94% in a burr medic cultivar; it also decreased seed size.

The effect of alfalfa mosaic virus on productivity of annual barrel medic, Medicago truncatula

1989 ◽  
Vol 40 (4) ◽  
pp. 807 ◽  
Author(s):  
DJ Dall ◽  
JW Randles ◽  
RIB Francki
Keyword(s):  
Root Growth ◽  
Mosaic Virus ◽  
Seed Production ◽  
Medicago Truncatula ◽  
Seed Yield ◽  
Virus Isolate ◽  
Alfalfa Mosaic Virus ◽  
The Other ◽  
Barrel Medic ◽  
Pot Trials

Alfalfa mosaic virus (AMV) infection of the annual barrel medic, Medicago truncatula, has been shown to cause significant reductions in growth and productivity in field and pot trials. The degree of reduction was dependent on the medic cultivar and the virus isolate. In some experiments herbage production was reduced by more than 50%. Although infection did not appear to be associated with significant changes in root growth, root nodulation of infected plants was about one-third less than that of healthy plants. Two AMV isolates showed different effects on seed production. Infection with one virus isolate was associated with a 15-30% decrease in seed production, and the virus was detected in more than 2% of seed from the infected plants, whereas the other isolate failed to reduce seed yield and did not appear to infect any seeds.

Impact of an insidious virus disease in the legume component on the species balance within self-regenerating annual pasture

1998 ◽  
Vol 131 (2) ◽  
pp. 155-170 ◽  
Author(s):  
R. A. C. JONES ◽  
D. A. NICHOLAS
Keyword(s):  
Seed Bank ◽  
Virus Disease ◽  
Alfalfa Mosaic Virus ◽  
Growing Season ◽  
Virus Spread ◽  
Mixed Species ◽  
Transmission Rates ◽  
Burr Medic ◽  
Seed Yields ◽  
The Impact

The consequences of sowing seed of burr medic (Medicago polymorpha) cultivars Circle Valley and Serena that was either free of or infected to different extents with alfalfa mosaic virus (AMV) was studied in mixed species pasture swards that regenerated annually. The swards were grazed by sheep and the predominant plant species in them were burr medic and capeweed (Arctotheca calendula). Serena matured earlier and was more tolerant of AMV infection than Circle Valley. Each year, seed-infected medic plants were the source for virus spread by aphids to healthy medic plants. When the extent of infection was determined in the fourth to sixth growing seasons, the amount of virus spread in the medic component of the swards varied between seasons. Final infection in plots originally sown with infected seed ranged from 47 to 93% for Serena and from 25 to 79% for Circle Valley. Viral seed transmission rates in medic seed produced each year by these plots ranged from 19 to 31% with Serena and from 3 to 7% with Circle Valley. Final percentage infection within swards originally sown with healthy seed (control plots) was smaller regardless of cultivar (0·1–7%) as were transmission rates in their harvested seed (0–0·6%).AMV infection of the burr medic in regenerated plots originally sown with Circle Valley seed diminished medic seed yields, thereby decreasing the proportion of medic in the seed bank. This decreased germination of medic but increased germination of capeweed. In control plots, plant densities were up to 36% greater in the medic and 52% smaller in the capeweed components than in plots originally sown with infected Circle Valley seed. In plots containing Serena there was a smaller decrease in medic seed yields due to AMV infection, so the impact on germination was less. In the fourth to sixth years from sowing, when yields were determined at different times after grazing ceased, there was either a small decrease (up to 8%) or no significant decrease in overall herbage yields due to infection with AMV. However, in plots originally sown with infected Circle Valley seed, the balance of medic to capeweed was altered in favour of capeweed, sometimes dramatically so (e.g. capeweed content increased from 19 to 45% in the fourth year from sowing). In contrast, by the end of the growing season the balance of medic to capeweed was little altered by the presence of the virus in plots containing Serena. Thus, infection with this insidious virus disease substantially diminished the ability of Circle Valley but not Serena medic to compete with other species such as capeweed in self-regenerated, mixed species pasture swards. It did this both directly by decreasing the competitive ability of the medic plants that became infected during the growing season, and indirectly via seed production and the seed bank, by altering the proportions in which the species germinated.

scholarly journals First Report of Alfalfa mosaic virus Infecting Tedera (Bituminaria bituminosa (L.) C.H. Stirton var. albomarginata and crassiuscula) in Australia

Plant Disease ◽  
2012 ◽  
Vol 96 (9) ◽  
pp. 1384-1384 ◽  
Author(s):  
R. A. C. Jones ◽  
D. Real ◽  
S. J. Vincent ◽  
B. E. Gajda ◽  
B. A. Coutts
Keyword(s):  
Mosaic Virus ◽  
Alfalfa Mosaic Virus ◽  
Plant Viruses ◽  
Yellow Mosaic Virus ◽  
Rt Pcr ◽  
First Report ◽  
Pasture Legumes ◽  
Bituminaria Bituminosa ◽  
Pcr Products ◽  
Burr Medic

Tedera (Bituminaria bituminosa (L.) C.H. Stirton vars albomarginata and crassiuscula) is being established as a perennial pasture legume in southwest Australia because of its drought tolerance and ability to persist well during the dry summer and autumn period. Calico (bright yellow mosaic) leaf symptoms occurred on occasional tedera plants growing in genetic evaluation plots containing spaced plants at Newdegate in 2007 and Buntine in 2010. Alfalfa mosaic virus (AlMV) infection was suspected as it often causes calico in infected plants (1,2) and infects perennial pasture legumes in local pastures (1,3). Because AlMV frequently infects Medicago sativa (alfalfa) in Australia and its seed stocks are commonly infected (1,3), M. sativa buffer rows were likely sources for spread by aphids to healthy tedera plants. When leaf samples from plants with typical calico symptoms from Newdegate (2007) and Buntine (2010) were tested by ELISA using poyclonal antisera to AlMV, Bean yellow mosaic virus (BYMV) and Cucumber mosaic virus (CMV), only AlMV was detected. When leaf samples from 864 asymptomatic spaced plants belonging to 34 tedera accessions growing at Newdegate and Mount Barker in 2010 were tested by ELISA, no AlMV, BYMV, or CMV were detected, despite presence of M. sativa buffer rows. A culture of AlMV isolate EW was maintained by serial planting of infected seed of M. polymorpha L. (burr medic) and selecting seed-infected seedlings (1,3). Ten plants each of 61 accessions from the local tedera breeding program were grown at 20°C in an insect-proof air conditioned glasshouse. They were inoculated by rubbing leaves with infective sap containing AlMV-EW or healthy sap (five plants each) using Celite abrasive. Inoculations were always done two to three times to the same plants. When both inoculated and tip leaf samples from each plant were tested by ELISA, AlMV was detected in 52 of 305 AlMV-inoculated plants belonging to 36 of 61 accessions. Inoculated leaves developed local necrotic or chlorotic spots or blotches, or symptomless infection. Systemic invasion was detected in 20 plants from 12 accessions. Koch's postulates were fulfilled in 12 plants from nine accessions (1 to 2 of 5 plants each), obvious calico symptoms developing in uninoculated leaves, and AlMV being detected in symptomatic samples by ELISA, inoculation of sap to diagnostic indicator hosts (2) and RT-PCR with AlMV CP gene primers. Direct RT-PCR products were sequenced and lodged in GenBank. When complete nucleotide CP sequences (666 nt) of two isolates from symptomatic tedera samples and two from alfalfa (Aq-JX112758, Hu-JX112759) were compared with that of AlMV-EW, those from tedera and EW were identical (JX112757) but had 99.1 to 99.2% identities to the alfalfa isolates. JX112757 had 99.4% identity with Italian tomato isolate Y09110. Systemically infected tedera foliage sometimes also developed vein clearing, mosaic, necrotic spotting, leaf deformation, leaf downcurling, or chlorosis. Later-formed leaves sometimes recovered, but plant growth was often stunted. No infection was detected in the 305 plants inoculated with healthy sap. To our knowledge, this is the first report of AlMV infecting tedera in Australia or elsewhere. References: (1) B. A. Coutts and R. A. C. Jones. Ann. Appl. Biol. 140:37, 2002. (2) E. M. J. Jaspars and L. Bos. Association of Applied Biologists, Descriptions of Plant Viruses No. 229, 1980. (3) R. A. C. Jones. Aust. J. Agric. Res. 55:757, 2004.

scholarly journals Impaired nodule function in Medicago polymorpha L. infected with alfalfa mosaic virus

1993 ◽  
Vol 124 (2) ◽  
pp. 243-250 ◽  
Author(s):  
J. M. WROTH ◽  
M. J. DILWORTH ◽  
R. A. C. JONES
Keyword(s):  
Mosaic Virus ◽  
Alfalfa Mosaic Virus ◽  
Medicago Polymorpha

scholarly journals Seed Transmissibility of Alfalfa mosaic virus in Soybean

2010 ◽  
Vol 11 (1) ◽  
pp. 41 ◽  
Author(s):  
B. He ◽  
O. L. Fajolu ◽  
R.-H. Wen ◽  
M. R. Hajimorad
Keyword(s):  
Mosaic Virus ◽  
Alfalfa Mosaic Virus ◽  
Seed Transmission ◽  
Infected Seed ◽  
Seed Transmissibility

Collectively, this report provides unequivocal evidence on Alfalfa mosaic virus (AMV) seed transmission in soybean. Infected seed may serve as a reservoir for survival and spread of AMV in soybean. Accepted for publication 18 November 2010. Published 27 December 2010.

scholarly journals Quantifying Effects of Seedborne Inoculum on Virus Spread, Yield Losses, and Seed Infection in the Pea seed-borne mosaic virus–Field Pea Pathosystem

2009 ◽  
Vol 99 (10) ◽  
pp. 1156-1167 ◽  
Author(s):  
B. A. Coutts ◽  
R. T. Prince ◽  
R. A. C. Jones
Keyword(s):  
Mosaic Virus ◽  
Seed Yield ◽  
Seed Transmission ◽  
Seed Infection ◽  
Virus Spread ◽  
Yield Losses ◽  
Seeding Rate ◽  
Transmission Rates ◽  
Infected Seed ◽  
Pea Seed

Field experiments examined the effects of sowing field pea seed with different amounts of infection with Pea seed-borne mosaic virus (PSbMV) on virus spread, seed yield, and infection levels in harvested seed. Plots were sown with seed with actual or simulated seed transmission rates of 0.3 to 6.5% (2005) or 0.1 to 8% (2006), and spread was by naturally occurring migrant aphids. Plants with symptoms and incidence increased with the amount of primary inoculum present. When final incidence reached 97 to 98% (2005) and 36% (2006) in plots sown with 6.5 to 8% infected seed, yield losses of 18 to 25% (2005) and 13% (2006) resulted. When incidence reached 48 to 76% in plots sown with 1.1-2 to 2% initial infection, seed yield losses were 15 to 21% (2005). Diminished seed weight and seed number both contributed to the yield losses. When the 2005 data for the relationships between percent incidence and yield or yield gaps were plotted, 81 to 84% of the variation was explained by final incidence and, for each 1% increase, there was a yield decline of 7.7 to 8.2 kg/ha. Seed transmission rates in harvested seed were mostly greater than those in the seed sown when climatic conditions favored early virus spread (1 to 17% in 2005) but smaller when they did not (0.2 to 2% in 2006). In 2007, sowing infected seed at high seeding rate with straw mulch and regular insecticide application resulted in slower spread and smaller seed infection than sowing at standard seeding rate without straw mulch or insecticide. When data for the relationship between final percent incidence and seed transmission in harvested seed were plotted (all experiments), 95 to 99% of the variation was explained by PSbMV incidence. A threshold value of <0.5% seed infection was established for sowing in high-risk zones.

Effects of applying insecticides to control aphid vectors and cucumber mosaic virus in narrow-leafed lupins Lupinus angustifolius)

1997 ◽  
Vol 37 (1) ◽  
pp. 93 ◽  
Author(s):  
A. M. Bwye ◽  
W. Proudlove ◽  
F. A. Berlandier ◽  
R. A. C. Jones
Keyword(s):  
Grain Yield ◽  
Cucumber Mosaic Virus ◽  
Mosaic Virus ◽  
Field Experiments ◽  
Virus Transmission ◽  
Primary Source ◽  
Lupinus Angustifolius ◽  
Current Season ◽  
Infected Seed ◽  
Carbamate Insecticides

Summary. Narrow-leafed lupins (Lupinus angustifolius) were sown in 4 field experiments to investigate the effects of applying organophosphorus and carbamate insecticides on the spread of cucumber mosaic virus (CMV), which is transmitted non-persistently by aphids. The seed sown carried 0 or 5% CMV infection and seed-infected plants were the primary source for subsequent virus transmission by aphids. Virus incidence was gauged by calculating the percentage of plants per plot showing typical current-season CMV symptoms. At final assessment in plots sown with 5% infected seed, recorded CMV incidence was always significantly smaller (up to 3-fold less) when they received sprays of pirimicarb and/or methamidophos every 2 weeks than when they received no insecticide. When single or double strategic sprays of methamidophos or a mixture of pirimicarb/thiometon were applied in late August or early September, they either decreased recorded CMV incidence (up to 2-fold less infection) or had no significant effect on it. Recorded CMV incidence was not significantly diminished by dressing seed with disulfoton or by single- or double-foliar applications of pirimicarb used alone. However, pirimicarb sprays applied every 2 weeks improved grain yield (24% increase), as also did single or double applications of pirimicarb (14%). In one experiment, applications of methamidophos every 2 weeks to plots originally sown with 5% infected seed resulted in increased grain yield (35%) and yields were increased in plots sown with healthy seed whether sprayed every 2 weeks with methamidophos or left unsprayed (42–61%). Pirimicarb suppressed numbers of colonising Acyrthosiphon kondoi and Aphis craccivora to a greater extent than those of Myzus persicae, especially when sprayed every 2 weeks. Single-, double- and sprays of methamidophos every 2 weeks also decreased numbers of Acyrthosiphon kondoi, but had less effect on M. persicae. When different insecticides were tested for their abilities to kill colonising, insecticide-resistant M. persicae, methamidophos was the most effective. This work suggests that single or double strategic foliar sprays of organophosphorus or carbamate insecticides cannot be relied on to control CMV adequately to be recommended for use in increasing grain yields in CMV-infected lupin grain crops.

THE SUCCESS OF THE LUCERNE MESSAGE IN MARLBOROUGH

1981 ◽  
pp. 179-183
Author(s):  
A.J. Cresswell
Keyword(s):  
North America ◽  
Weed Control ◽  
Seed Yield ◽  
Insect Pest ◽  
Fold Increase ◽  
Plant Spacing ◽  
Insect Pest Control ◽  
One Year ◽  
Seed Yields ◽  
New Cultivars

This paper, as well as being a testimonial to the benefit the writer has received from the Grassland Association, shows how the knowledge of scientists has been used to increase lucerne seed yields by methods of growing resistant cultivars especially for seed production as opposed to growing for hay, silage or grazing. It shows how new cultivars can be multiplied quickly by growing two crops in one year, one in each hemisphere, by using low seeding rates, wide plant spacing and very good weed control. Increased flowering of the crop has been achieved by the use of boron and the choice of time of closing; better pollination has been achieved by the use of more efficient bees - two varieties of which have been imported from North America. Weed and insect pest control and the use of a desiccant at harvest are contributing to a four-fold increase in seed yield, which should double again soon,

THESIS SUMMARY STUDIES OF ALFALFA MOSAIC VIRUS AND SUBTERRANEAN CLOVER RED LEAF VIRUS

1979 ◽  
pp. 163-164
Author(s):  
P.B. Teh
Keyword(s):  
Mosaic Virus ◽  
Alfalfa Mosaic Virus ◽  
Subterranean Clover ◽  
Test Plant ◽  
Transmission Frequency ◽  
Virus Source ◽  
Leaf Virus

AMV was shown to be transmitted by sap, aphids and through lucerne seed, but not by Cuscuta. Virus source and test plant influenced transmission frequency. Sap-inoculation tests showed that 20 species of plants were susceptible to this virus. Thirteen species of plants from the fields where AMV had been detected were tested but only three were found to be infected with the virus.

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