Medicago truncatula and other annual Medicago spp . – interactions with root and foliar fungal, oomycete, and viral pathogens

2019 ◽  
pp. 293-306 ◽  
Author(s):  
Martin J. Barbetti ◽  
Ming Pei You ◽  
Roger A.C. Jones
Keyword(s):  
Medicago Truncatula ◽  
Viral Pathogens ◽  
Annual Medicago

Strategies for control of Phoma black stem in annual Medicago species

1989 ◽  
Vol 29 (5) ◽  
pp. 635 ◽  
Author(s):  
MJ Barbetti
Keyword(s):  
Disease Severity ◽  
Medicago Truncatula ◽  
Field Trial ◽  
Subsequent Development ◽  
Field Site ◽  
Infected Seed ◽  
Annual Medicago ◽  
And Control ◽  
Medicago Species ◽  
Selection Of

Strategies for control of Phoma black stem disease in annual Medicago species through selection of cultivars with increased resistance to Phoma medicaginis, fungicidal spray applications to swards, and fungicidal control of seedborne infection, were investigated. Fiftyseven annual Medicago cultivars and lines were screened for resistance in the field in 1 m rows over 2 consecutive seasons. There were significant differences in resistance among species and also between lines and cultivars of any particular species. Three M. rugosa cultivars were very highly resistant and most cultivars and lines showed some resistance. In a field trial, the fungicides benomyl, carbendazim, flutriafol, propiconazole, thiabendazole and triadimefon were tested for their efficacy in controlling Phoma black stem disease. All fungicides reduced disease severity in the sward and, except for thiabendazole, the percentage burrs with Phoma lesions. The role and control of seed-borne P. medicaginis in causing Phoma black stem disease in Medicago truncatula and M. polymorpha var. brevispina at a field site was also investigated. Seed-borne P. medicaginis caused subsequent development of Phoma black stem disease in swards sown with infected seed. Disease appeared earlier, developed faster and became much more severe in M. truncatula cv. Cyprus than in M. polymorpha cv. Serena. Application of benomyl seed treatments (0.1 and 0.5% w/w) resulted in only a 4-5 week delay in the onset of Phoma black stem symptoms.

Seedling resistance to pea aphid of lucerne, annual medic and clover species in Victoria

1981 ◽  
Vol 21 (112) ◽  
pp. 506 ◽  
Author(s):  
PM Ridland ◽  
GN Berg
Keyword(s):  
Medicago Truncatula ◽  
Acyrthosiphon Pisum ◽  
Trifolium Subterraneum ◽  
Pea Aphid ◽  
Aphid Population ◽  
Seedling Mortality ◽  
Seedling Resistance ◽  
The Usa ◽  
Annual Medicago ◽  
High Level

Twenty-two lines of lucerne, six of annual Medicago spp., seven of Trifolium subterraneum, six of T. repens and six of several other Trifolium spp. were tested for seedling resistance to pea aphid, Acyrthosiphon pisum (Harris), in glasshouse tests at Burnley, Victoria. In general, lucerne cultivars selected for resistance to North American biotypes of the aphid were resistant to the Victorian aphid population. However, in our tests, two cultivars (Matador and Pioneer Brand 545) that were classed as susceptible to pea aphid in the USA. were as resistant as WL 31 8, a cultivar selected in the U.SA. for resistance to pea aphid. Medicago truncatula cvv. Borung and Cyprus were highly susceptible to pea aphid. They were more severely damaged than M. sativa cv. Hunter River, which was the most susceptible of the lucerne cultivars tested. M. rugosa cv. Paragosa had a high level of resistance while M. truncatula cvv. Hannaford and Jemalong, and M. littoralis cv. Harbinger were stunted but had only a low level of seedling mortality. Of the seven cultivars of T. subterraneum tested, only cv. Clare had a high level of aphid resistance, and all lines of T. repens were susceptible. The lines of T. fragiferum, T. incarnatum and T. pratense were more resistant than the susceptible check, T. subterraneum cv. Daliak, and should at least be tolerant in the field.

Genome size and base composition in Medicago sativa and M. truncatula species

Genome ◽  
1994 ◽  
Vol 37 (2) ◽  
pp. 264-270 ◽  
Author(s):  
François Blondon ◽  
Dominique Marie ◽  
Spencer Brown ◽  
Adam Kondorosi
Keyword(s):  
Flow Cytometry ◽  
Medicago Sativa ◽  
Key Words ◽  
Genome Size ◽  
Medicago Truncatula ◽  
Intraspecific Variation ◽  
Base Composition ◽  
Annual Medicago

The genome size (1C value) and base composition of 14 ecotypes of two species of tetraploid and diploid Medicago have been assessed by flow cytometry. These parameters vary both between and within species. The diploid annual Medicago truncatula Gaertn. had the smallest genome of the group studied (which also covered M. sativa L. subsp. sativa, M. sativa L. subsp. caerulea (Less. ex Ledeb.) Schmalh., M. sativa L. subsp. quasifalcata Sinsk., M. sativa L. subsp. × varia (Martyn) Arcangeli; however, its ecotypes revealed substantial intraspecific variation. The smallest M. truncatula genome observed was ecotype 108-1 with 1C = 0.49 pg and 38.1% GC and the largest was Jemalong with 1C = 0.57 pg and 38.6% GC. The degree of polysomaty in these Medicago was low, although in some tissues the frequency of cells with 4C nuclei reached 50%.Key words: Medicago, genome size, base composition, flow cytometry, symbiosis.

Nodulation and growth of Medicago truncatula on acid soils. I. Effect of calcium carbonate and inoculation level on the nodulation of Medicago truncatula on a moderately acid soil

1970 ◽  
Vol 21 (3) ◽  
pp. 427 ◽  
Author(s):  
AD Robson ◽  
JF Loneragan
Keyword(s):  
Calcium Carbonate ◽  
Medicago Truncatula ◽  
Soil Ph ◽  
Soil Acidity ◽  
Rhizobium Meliloti ◽  
Acid Soil ◽  
Acid Soils ◽  
Acid Tolerant ◽  
Annual Medicago ◽  
Medicago Species

On a moderately acid soil (pH 4.6 in 115 suspension of soil in 0.01M calcium chloride), nodulation of Medicago truncatula cv. Cyprus responded markedly to increasing applications of calcium carbonate, which increased soil pH. Since the effect of increasing soil pH on the percentage nodulation could be replaced to a large extent by increasing the inoculation level, it appeared that nodulation was restricted by the inability of Rhizobium meliloti to survive or multiply in the acid soil. The growth of R, meliloti appeared more sensitive to soil acidity than growth of the host plant of annual Medicago species. It is suggested that more acid-tolerant strains of R. meliloti would permit annual Medicago species to be grown successfully on moderately acid soils, thus extending the range of soils suitable for the growth of these species.

Nodulation and growth of Medicago truncatula on acid soils. II. Colonization of acid soils by Rhizobium meliloti

1970 ◽  
Vol 21 (3) ◽  
pp. 435 ◽  
Author(s):  
AD Robson ◽  
JF Loneragan
Keyword(s):  
Calcium Carbonate ◽  
Medicago Truncatula ◽  
Rhizobium Meliloti ◽  
Acid Soils ◽  
Sandy Soils ◽  
Acid Tolerant ◽  
Second Year ◽  
Annual Medicago ◽  
Medicago Species ◽  
Better Than

Six strains of Rhizobium meliloti varied greatly in their ability to colonize two moderately acid sandy soils (pH 5.0-5.1 in 115 suspension of soil in 0.01M calcium chloride) in the year of sowing inoculated lime-coated seeds of Medicago truncatula. The strains also varied in their ability to nodulate M. truncatula in the year after sowing. With all rhizobial strains and on both soils, calcium carbonate applied in the year of sowing strongly promoted colonization in the year of sowing. It also greatly increased nodulation and growth of M. truncatula in the year after sowing. Apparently calcium carbonate increased second year nodulation by promoting the colonization of the acid soils by R. meliloti in the year of sowing. Differences among strains in second year nodulation appeared to be related to differences in the ability of the strains to colonize the soils in the year of sowing. Strains isolated from moderately acid sandy soils were markedly superior in both properties, and on both soils, to strain SU47 from commercial inoculum, but were generally no better than strain U45 from commercial inoculum. Even the most acid-tolerant strains colonized the acid soils relatively slowly. It is suggested that R. meliloti strains in general have a poor ability to colonize acid soils and that this property is a major factor limiting the growth and persistence of annual Medicago species on acid soils in the field.

The Diagnosis of Viral Disease by Electron Microscopy

1982 ◽  
Vol 40 ◽  
pp. 270-273
Author(s):  
William B. McCombs ◽  
Cameron E. McCoy
Keyword(s):  
Electron Microscopy ◽  
Hospital Stay ◽  
Viral Infections ◽  
Medical Profession ◽  
Bacterial Pathogens ◽  
Viral Disease ◽  
Viral Pathogens ◽  
Academic Interest ◽  
The Past

Recent years have brought a reversal in the attitude of the medical profession toward the diagnosis of viral infections. Identification of bacterial pathogens was formerly thought to be faster than identification of viral pathogens. Viral identification was dismissed as being of academic interest or for confirming the presence of an epidemic, because the patient would recover or die before this could be accomplished. In the past 10 years, the goal of virologists has been to present the clinician with a viral identification in a matter of hours. This fast diagnosis has the potential for shortening the patient's hospital stay and preventing the administering of toxic and/or expensive antibiotics of no benefit to the patient.

Sign in / Sign up

Export Citation Format

Share Document