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.

Seed production and persistence of Carnamah and other early strains of Trifolium subterraneum in the wheatbelt of Western Australia

1967 ◽  
Vol 7 (24) ◽  
pp. 25 ◽  
Author(s):  
GB Taylor ◽  
RC Rossiter
Keyword(s):  
Seed Production ◽  
Seed Yield ◽  
Western Australia ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Growing Season ◽  
Early Flowering ◽  
The Other ◽  
Factors Affecting ◽  
Seed Yields

Seed production and persistence of the Carnamah, Northam A, Dwalganup, and Geraldton strains of subterranean clover (Trifolium subterraneum L.) were examined in undefoliated swards in the wheatbelt of Western Australia. The early flowering characteristic of Carnamah was not always associated with higher seed yields. Only when there was a well-defined, early finish to the growing season, or when flowering was very much earlier in Carnamah (viz., following an early 'break' to the season), did this strain clearly outyield both Northam A and Geraldton. The seed yield of Dwalganup was generally inferior to that of the other strains. Factors affecting regeneration are discussed. Under low rainfall conditions, poorer germination-regulation of Carnamah, compared with Geraldton and Northam A, would be expected to result in poorer persistence unless offset by higher seed yields in the Carnamah strain.

scholarly journals Experimental studies on seed production tropical grasses in Kenya. 6. The effect of harvest date on seed yield in varieties of Setaria sphacelata, Chloris gayana and Panicum coloratum.

1973 ◽  
Vol 21 (1) ◽  
pp. 3-11
Author(s):  
J.G. Boonman
Keyword(s):  
Seed Production ◽  
Seed Yield ◽  
Experimental Studies ◽  
The Other ◽  
Harvest Date ◽  
Tropical Grasses ◽  
Panicum Coloratum ◽  
Setaria Sphacelata ◽  
Chloris Gayana ◽  
Late Abstract

Setaria sphacelata cv. Nandi I and Nandi III, Chloris gayana cv. Mbarara, Masaba and Pokot, and Panicum coloratum cv. Solai were grown for seed and harvested on a range of dates beginning 3-4 weeks after initial head emergence (defined as 5-10 heads/m2). Harvesting date was not very critical, and harvesting could normally be spread over 1-2 weeks. The interval between initial heading and optimum harvest date was normally 6-7 weeks. In most crops considerable shedding of spikelets (up to 30-50% in P. coloratum, rather less in the other 2 species) could be tolerated before yield of pure germinating seed fell with delay in harvesting. It was suggested that most of the spikelets which were shed early were empty. Cultivars which headed early produced nearly twice as much seed as those which headed late. (Abstract retrieved from CAB Abstracts by CABI’s permission)

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.

A comparison of the persistence of Medicago truncatula cv. Paraggio with other annual medics in the Victorian Mallee

1993 ◽  
Vol 33 (4) ◽  
pp. 443 ◽  
Author(s):  
RA Latta ◽  
PE Quigley
Keyword(s):  
Plant Regeneration ◽  
Seed Production ◽  
Medicago Truncatula ◽  
Seed Set ◽  
Agricultural Productivity ◽  
The Other ◽  
Plant Densities ◽  
Seed Reserves ◽  
Annual Medics ◽  
Better Than

The annual medic Medicago truncatula cv. Paraggio has been widely sown in pastures throughout the Victorian Mallee region; however, its ability to persist in cereal pasture rotations is not known. Seed permeability and production, and plant regeneration of Paraggio, were studied in the field over 4 years, and the changes in its seed reserve were examined under 3 different cereal-pasture rotations. When compared with medic cvv. Parabinga, Harbinger, and Jemalong, Paraggio had up to twice the level of permeable seed over the summer-autumn period in 2 years (7-36% v. 2.5-19%). Paraggio produced 336-928 kg/ha of seed over 3 years, and after seed production was halted, it regenerated at densities of 150-1438 plants/m2 over the next 4 years. These results were generally the same as, or better than, the other cultivars. When seed set occurred in 1 and 2 years in the pasture phase of a 2- and 3-year rotation, respectively, Paraggio seed reserves were maintained at >4000 seeds/m2. This study demonstrated that Paraggio resulted in superior plant densities when grown in a number of typical rotations. It persisted satisfactorily and is expected to improve agricultural productivity in shor-tterm cereal-pasture rotations.

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.

Inoculation with root nodulating bacteria reduces the susceptibility of Medicago truncatula and Lupinus angustifolius to cucumber mosaic virus (CMV) and addition of nitrate partially reverses the effect

1993 ◽  
Vol 44 (8) ◽  
pp. 1917 ◽  
Author(s):  
WS Wahyuni ◽  
JW Randles
Keyword(s):  
Cucumber Mosaic Virus ◽  
Mosaic Virus ◽  
Medicago Truncatula ◽  
Growth Conditions ◽  
Lupinus Angustifolius ◽  
Acetylene Reduction Activity ◽  
High Concentration ◽  
Virus Particles ◽  
Barrel Medic ◽  
Virus Content

The susceptibility of Medicago truncatula ssp. truncatula (barrel medic) cv. Jemalong and Lupinus angustifolius (lupin) cv. Illyarrie and Gungurru to cucumber mosaic virus (CMV) was reduced by prior inoculation of seedlings with commercial strains of root nodulating bacteria (Rhizobium or Bradyrhizobium, respectively). This effect was observed both with strains of CMV originating from legumes and with strains originating from non-legumes. The virus content of the nodulated plants which were successfully inoculated was not markedly affected by nodulation, indicating that nodulation affected susceptibility to inoculation, and not the ability of CMV to replicate. In lupins, the reduction in susceptibility followed mechanical and graft inoculation of plants with virus. The effect was first noted at about the time that acetylene reduction activity (ARA) was first detected and just before nodules appeared. Virus-infected lupins showed a delay in the development of nodules and a reduced ARA, compared with uninfected plants, indicating that there was a two-way interaction between the virus and Bradyrhizobium. Different growth conditions did not affect the ARA values, the severity of symptoms or the susceptibility of lupin to CMV. A minimum level of nitrate was required for medic growth both with and without the root nodulating bacteria. The addition of higher levels of nitrate to the nutrient solution partially reversed the effect of the nodulating bacteria, in that it increased the susceptibility of the plants. Medics not inoculated with Rhizobium and supplied with a high concentration of nitrate were the most susceptible to CMV. In a test to compare competent with incompetent bacteria, Rhizobium strain 1021 (which fixes N2) and its mutant, Rm 1491 (which does not fix N2), did not differ in their effect on susceptibility. Aggregates of virus particles and crystals of virus were found in nodule cells of medic plants, but virus particles and bacteroids were not found in the same cell. Individual and aggregated virus particles were commonly located along the cell wall of cells free of bacteroids. It is concluded that infection by root nodulating bacteria and external nitrogen supplementation have opposite effects on the susceptibility of barrel medic and lupin to CMV, and that CMV, in turn, reduces the effectiveness of the symbiosis between these bacteria and their host. Nodulation has little effect on virus replication, and both virus and bacteroids occur in the same nodule tissue.

Resistance to Alfalfa mosaic virus in transgenic barrel medic lines containing the virus coat protein gene

2001 ◽  
Vol 52 (1) ◽  
pp. 67 ◽  
Author(s):  
K. W. Jayasena ◽  
M. R. Hajimorad ◽  
E. G. Law ◽  
A-U. Rehman ◽  
K. E. Nolan ◽  
...  
Keyword(s):  
Coat Protein ◽  
Mosaic Virus ◽  
Medicago Truncatula ◽  
Coat Protein Gene ◽  
Protein Gene ◽  
Single Gene ◽  
Alfalfa Mosaic Virus ◽  
Systemic Infection ◽  
Gene Copy ◽  
Sense Orientation

Medicago truncatula is used as a pasture legume and a source of nitrogen for grain crops in southern Australia. Alfalfa mosaic virus (AMV) infection reduces herbage production and nodulation. The coat protein gene of a South Australian strain of AMV (AMV N20) has been transferred to Medicago truncatula cv. Jemalong 2HA using Agrobacterium-mediated transformation. The most detailed investigations were carried out with the coat protein gene in the sense orientation (CP+). Progeny (T1, T2, T3) raised from self-pollinated primary transformants (T0) containing the coat protein CP+ gene were resistant to AMV. Based on Southern analysis and segregation, the transformants contained a single gene copy. In the T3 generation, one line was immune and one line showed resistance to AMV N20. The immune line contained no detectable virus when plant sap from either inoculated or systemic leaves was bioassayed on Phaseolus vulgaris. This line was also immune to the heterologous AMV S40 isolate. A line with the coat protein gene in antisense orientation (CP–) showed delayed systemic infection but was not immune. We conclude that coat protein mediated protection (CPMP) is an effective strategy for controlling AMV infection and should be further evaluated in the field.

Virus symptomatology in accessions of the Medicago truncatula core collection and identification of virus resistance phenotypes

2011 ◽  
Vol 62 (8) ◽  
pp. 686 ◽  
Author(s):  
M. Saqib ◽  
B. E. Gadja ◽  
M. G. K. Jones ◽  
R. A. C. Jones
Keyword(s):  
Mosaic Virus ◽  
Medicago Truncatula ◽  
Virus Resistance ◽  
Core Collection ◽  
Alfalfa Mosaic Virus ◽  
Resistance Breeding ◽  
Yellow Mosaic Virus ◽  
Diverse Range ◽  
Model Legume ◽  
Pasture Legumes

Plants of 212 accessions from the core collection of model legume species Medicago truncatula were inoculated with infective sap containing Alfalfa mosaic virus (AMV, isolate EW), Bean yellow mosaic virus (BYMV, isolate MI) or Cucumber mosaic virus (CMV, isolate SN-1). A diverse range of systemic symptoms were obtained that varied widely in severity depending on the combination of virus isolate and accession, or, especially with AMV, some accessions became infected but did not display symptoms. The delay between virus inoculation and symptom appearance normally varied from 1 to 4 weeks, but with CMV it took up to 8 weeks in two accessions. Five (AMV), 59 (BYMV) and 22 (CMV) core accessions remained uninfected systemically. Plants of most of these accessions, and some that died or gave susceptible phenotypes, were then inoculated with two additional isolates of AMV (eight accessions), or two distinct strains of BYMV (58 accessions) and CMV (21 accessions). Plants of accession 11715 remained uninfected by CMV isolates CP (CMV subgroup 1) and LW (CMV subgroup 2), but those of all other previously uninfected accessions became infected systemically by all three viruses. All accessions inoculated with AMV isolates Aq and Hu, and most inoculated with BYMV isolate LKoj1-NN (generalist strain), BYMV isolate LP-1 (lupin strain), and CMV isolates CP and LW developed typical susceptible phenotypes. However, systemic hypersensitive phenotypes developed with BYMV LKoj1-NN and LP-1 in plants of 4456, or with LKoj1-NN only in 774, 1526, 4327, 14829, 15268, 22922 and 25654; 15268 and 25654 had developed this phenotype previously with MI (generalist strain). Similarly, plants of 21362 developed this phenotype with CMV CP and LW, while plants of 1526, 2748 and 31443 developed it with CP; 2748, 21632 and 31443 had developed it previously with SN-1 (mixture of subgroups 1 and 2). Once the genetic bases of the BYMV and CMV resistances found in M. truncatula are understood, they may prove useful in future virus resistance breeding among crop and pasture legumes.

Herbage and seed production of three barrel medic (Medicago truncatula) cultivars and harbinger medic (Medicago littoralis) in the Victorian Mallee

1966 ◽  
Vol 6 (23) ◽  
pp. 361 ◽  
Author(s):  
RL Amor
Keyword(s):  
Seed Production ◽  
Medicago Truncatula ◽  
Research Station ◽  
Barrel Medic ◽  
Medicago Littoralis ◽  
Second Year

The herbage and seed production of three barrel medic (Medicago truncatula Gaertn.) cultivars and harbinger medic (Medicago littoralis Rhode) were compared for five years in first- and second-year pure ungrazed stands at the Mallee Research Station, Walpeup, Victoria. The cultivars did not differ consistently in spring production of herbage, but they did differ in winter production. Harbinger medic produced almost twice as much winter herbage as commercial barrel medic and Cyprus barrel medic. Barrel medic 173 produced more winter herbage than the commercial or Cyprus cultivars, but less than harbinger medic. Harbinger medic and Cyprus barrel medic flowered a fortnight earlier, and produced more seed than commercial barrel medic and barrel medic 173.

Sign in / Sign up

Export Citation Format

Share Document