Resistance to subterranean clover mottle virus in subterranean clover results from restricted cell-to-cell movement

1995 ◽  
Vol 46 (3) ◽  
pp. 633 ◽  
Author(s):  
R Njeru ◽  
RAC Jones ◽  
K Sivasithamparam ◽  
MGK Jones
Keyword(s):  
Cell Movement ◽  
Systemic Infection ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Tissue Level ◽  
Cell Infection ◽  
Cell Level ◽  
Resistant Cultivars ◽  
Antibody Staining

Subterranean clover mottle sobemovirus (SCMoV) is an important pathogen of subterranean clover (Trifolium subterraneum) pastures in Australia. Cultivars of subterranean clover are susceptible (e.g. Dalkeith, Woogenellup), moderately susceptible (e.g. Green Range), partially resistant (e.g. Goulburn) or highly resistant (e.g. Meteora, Trikkala) to SCMoV. The resistant class does not become systemically infected on sap inoculation, while only a proportion of plants develop systemic infection with the moderately susceptible and partially resistant classes (Wroth and Jones 1992b; Ferris and Jones 1994). These different classes were used to examine the basis of SCMoV resistance using cell biological approaches. Virus levels were quantified at the tissue level by ELISA and at the cell level by counting protoplasts which fluoresced after antibody staining. Three aspects were investigated: (1) initial cell infection, (2) frequencies of cell infection in sap-inoculated leaves and in systemically infected leaves from graft-inoculated plants, and (3, ability of the virus to replicate in isolated protoplasts. Fewer and smaller starch lesions formed in inoculated leaves of a highly resistant cultivar than in those of moderately susceptible and susceptible cultivars. In protoplasts isolated from epidermal cell strips from inoculated leaves, initially the numbers of fluorescing protoplasts were the same for all four classes of cultivars (5-7%). Subsequently, however, the numbers remained unchanged for the two highly resistant cultivars, but increased considerably in the susceptible one used, and to a lesser extent in the moderately susceptible and partially resistant ones. For protoplasts isolated from whole inoculated leaves, the percentage of protoplasts that fluoresced was greatest in the susceptible cultivars used, lower in the moderately susceptible and partially resistant cultivars, and least in the highly resistant ones. All classes became systemically infected when graft-inoculated, but with the systemically infected leaves the proportions of protoplasts that fluoresced were least for the highly resistant and greatest for the susceptible classes. When protoplasts were inoculated with SCMoV in vitro, the proportions which fluoresced were the same (53-56%) for highly resistant, moderately susceptible and susceptible cultivars, showing that resistance was not expressed at the single cell level as an inhibition of virus replication. Because movement of SCMoV was restricted in inoculated leaves of the highly resistant class (starch lesion, epidermal strip and whole leaf data) and in graft-induced systemically infected leaves, it is concluded that the basis of resistance to SCMoV in highly resistant cultivars of subterranean clover is restriction of cell-to-cell movement of the virus.

Varietal reactions of Trifolium subterraneum L. to Phaseolus virus 2 Pierce.

1954 ◽  
Vol 5 (4) ◽  
pp. 598 ◽  
Author(s):  
EM Hutton ◽  
JW Peak
Keyword(s):  
Trypan Blue ◽  
Continuous Distribution ◽  
Systemic Infection ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Epidermal Cells ◽  
Severe Strain ◽  
Resistant Varieties ◽  
Lethal Reaction ◽  
The Mean

A number of varieties of subterranean clover (Trifolium subterraneum L.) were tested with a severe strain of Phaseolus virus 2 Pierce. Northam First Early, Dwalganup, and Pink Flowered gave lethal necrotic reactions while the rest developed mottles and chlorosis of different degrees of intensity. Reductions in the mean fresh weights of plants of five subterranean clover varieties ranged from 26.1 to 76.7 per cent. Epidermal cells of mottled leaves contained irregular aggregates of viroplasts stained by treatment with phloxine-trypan blue. Viroplasts in young tip leaves did not stain if the plants were held at temperatures below 44.6°F while those in mature basal leaves were not so affected. The lethal-reactors Northam First Early, Dwalganup, and Pink Flowered were resistant in the field to Phaseolus virus 2. With hand inoculation in the glass-house an average of 10 per cent. of plants of these varieties remained free from systemic infection, whereas all the plants of mottle-reacting varieties became systemically infected. The virus had a discontinous distribution in plants of lethal-reactors, compared with a continuous distribution in those of mottle-reactors such as Mount Barker. The lethal reaction is heritable in a dominant fashion in most crosses, so that the development of desirable new virus- resistant varieties is possible.

scholarly journals Matrix-transmitted paratensile signaling enables myofibroblast–fibroblast cross talk in fibrosis expansion

2020 ◽  
Vol 117 (20) ◽  
pp. 10832-10838 ◽  
Author(s):  
Longwei Liu ◽  
Hongsheng Yu ◽  
Hui Zhao ◽  
Zhaozhao Wu ◽  
Yi Long ◽  
...  
Keyword(s):  
Cross Talk ◽  
Growth Models ◽  
Tissue Level ◽  
Dependent Manner ◽  
Cell Level ◽  
Fibrous Matrix ◽  
Calcium Dependent ◽  
Spatiotemporal Feature ◽  
Fibroblast Foci

While the concept of intercellular mechanical communication has been revealed, the mechanistic insights have been poorly evidenced in the context of myofibroblast–fibroblast interaction during fibrosis expansion. Here we report and systematically investigate the mechanical force-mediated myofibroblast–fibroblast cross talk via the fibrous matrix, which we termed paratensile signaling. Paratensile signaling enables instantaneous and long-range mechanotransduction via collagen fibers (less than 1 s over 70 μm) to activate a single fibroblast, which is intracellularly mediated by DDR2 and integrin signaling pathways in a calcium-dependent manner through the mechanosensitive Piezo1 ion channel. By correlating in vitro fibroblast foci growth models with mathematical modeling, we demonstrate that the single-cell-level spatiotemporal feature of paratensile signaling can be applied to elucidate the tissue-level fibrosis expansion and that blocking paratensile signaling can effectively attenuate the fibroblast to myofibroblast transition at the border of fibrotic and normal tissue. Our comprehensive investigation of paratensile signaling in fibrosis expansion broadens the understanding of cellular dynamics during fibrogenesis and inspires antifibrotic intervention strategies targeting paratensile signaling.

The in vitro inhibition of Phytophthora clandestina by some rhizobia and the possible role of Rhizobium trifolii in biological control of Phytophthora root rot of subterranean clover

1999 ◽  
Vol 50 (8) ◽  
pp. 1469 ◽  
Author(s):  
S. Simpfendorfer ◽  
T. J. Harden ◽  
G. M. Murray
Keyword(s):  
Biological Control ◽  
Root Rot ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Root Disease ◽  
Rhizobium Trifolii ◽  
Biological Control Agents ◽  
Control Activity ◽  
Phytophthora Root Rot

The interaction between 29 isolates of Rhizobium and the in vitro growth of 3 strains of Phytophthora clandestina was investigated to determine the potential of these bacteria as biological control agents against root rot of subterranean clover (Trifolium subterraneum L.). The biological control activity of Rhizobium on the severity of root disease in seedlings was also investigated under glasshouse conditions. Thirteen of the 29 Rhizobium isolates caused significant reductions in the hyphal growth of the 3 P. clandestina isolates examined. Inoculation of seedlings with Rhizobium trifolii reduced the severity of root disease by 14–58% with corresponding increases in dry matter production of 20–73%. These results indicate that Rhizobium species have potential as biological control agents against the root rot of T. subterraneum seedlings caused by P. clandestina.

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.

Plant factors influencing the nutritive value of some temperate annual pasture species

1973 ◽  
Vol 13 (63) ◽  
pp. 404 ◽  
Author(s):  
JG McIvor ◽  
DF Smith
Keyword(s):  
Nutritive Value ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Growth Cycle ◽  
Matter Content ◽  
In Vitro Digestibility ◽  
Dry Matter Content ◽  
Hordeum Leporinum ◽  
Brome Grass

Changes in herbage production, dry matter content, nitrogen content and in vitro digestibility of two sown species-subterranean clover (Trifolium subterraneum) and annual ryegrass (Lolium rigidum) - and five common volunteer species-capeweed (Arctotheca calendula), musky crowfoot (Erodium moschatum), barley grass (Hordeum leporinum), ripgut brome grass (Bromus rigidus) and soft brome grass (Bromus mollis)-were measured throughout their growth cycle. The volunteer species compared favourably with the sown species for these measurements and should be capable of providing nutritious grazing for animals.

Effect of calcium on the growth and virulence of Phytophthora clandestina

2000 ◽  
Vol 40 (1) ◽  
pp. 47 ◽  
Author(s):  
S. Simpfendorfer ◽  
T. J. Harden
Keyword(s):  
Fungal Pathogen ◽  
Mycelial Growth ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
In Vitro Growth ◽  
Seedling Biomass ◽  
Pathogenic Races ◽  
Glasshouse Experiment ◽  
The Individual

Calcium was found to significantly stimulate both the mycelial growth and virulence of Phytophthora clandestina, the major soilborne fungal pathogen of subterranean clover (Trifolium subterraneum L.). On average, the addition of calcium as either CaCO3 or CaCl2 to 3 artificial media increased the in vitro growth of 15 isolates from 20 to 135%. Calcium was also shown to increase the severity of root disease caused by 6 isolates of P. clandestina by up to 100% in a glasshouse experiment. The addition of Ca2+ as CaCl2 had a greater stimulatory effect on the virulence of P. clandestina towards cv. Woogenellup seedlings (up to 57% reduction in seedling biomass) than supplementing with CaCO3 (maximum 36% decrease). The virulence of 6 isolates from 3 different pathogenic races of P. clandestina were examined in the glasshouse experiment. Differences in the virulence of P. clandestina towards cv. Woogenellup seedlings was shown to be dependent on the individual isolate rather than the pathogenic race to which it is assigned.

scholarly journals Agronomic characteristics of annual Trifolium legumes and nutritive values as predicted by near-infrared reflectance (NIR) spectroscopy

2011 ◽  
Vol 62 (12) ◽  
pp. 1078 ◽  
Author(s):  
X. Li ◽  
R. L. Ison ◽  
R. C. Kellaway ◽  
C. Stimson ◽  
G. Annison ◽  
...  
Keyword(s):  
Organic Matter ◽  
Near Infrared ◽  
Spectral Characteristics ◽  
Nir Spectroscopy ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Infrared Reflectance ◽  
Near Infrared Reflectance ◽  
Stem Leaf

A range of annual legume genotypes comprising one line of Trifolium subterraneum, four lines of T. michelianum, 11 of T. resupinatum var. resupinatum, and one line of T. resupinatum var. majus were grown in glasshouses under temperature regimes of 10−15°C and 16−21°C. Dry matter (DM) weights of stem, leaf, and flower tissues were measured when plants had six nodes, at first flower appearance, and at senescence. All samples were scanned by near-infrared reflectance spectroscopy (NIRS). One-third of the samples, covering the range of spectral characteristics, were analysed for in vitro digestible organic matter (DOMD), organic matter, crude protein (CP), neutral detergent fibre (NDF), lignin, cellulose, and the hemicellulosic polysaccharide monomers arabinose, xylose, mannose, galactose, and rhamnose. These data were used to develop calibration equations from which the composition of the remaining samples was predicted by NIRS. The higher temperature resulted in plants reaching respective phenological stages earlier, but did not affect either DM yields of total plant, stem, leaf, and petiole tissues or the proportions of each fraction. In vitro DOMD and arabinose and galactose levels decreased, while lignin, cellulose, NDF, xylose, mannose, and rhamnose levels increased with advancing maturity. In vitro DOMD was positively associated with contents of CP, arabinose, galactose, and the arabinose/xylose ratio and was negatively associated with contents of lignin, cellulose, NDF, xylose, mannose, and rhamnose. Lignin contents were highly correlated with levels of both xylose and mannose. Stems were more digestible than leaves in subterranean clover and T. resupinatum var. majus. The study also demonstrated that NIRS can be used routinely as a quick, inexpensive, and reliable laboratory technique to predict feed components of annual Trifolium legumes.

Anti-methanogenic advantage of biserrula (Biserrula pelecinus) over subterranean clover (Trifolium subterraneum) from in vitro fermentation is maintained across growth stages and cutting treatments

2019 ◽  
Vol 70 (3) ◽  
pp. 263
Author(s):  
Bidhyut Kumar Banik ◽  
Zoey Durmic ◽  
William Erskine ◽  
Clinton Revell
Keyword(s):  
Growth Stage ◽  
Nutritive Value ◽  
Subterranean Clover ◽  
In Vitro Study ◽  
Trifolium Subterraneum ◽  
Reproductive Stage ◽  
Growth Stages ◽  
Plant Collection ◽  
Grazing Systems

The annual forage legume biserrula (Biserrula pelecinus L.) offers a promising opportunity as a low-methanogenic, bioactive pasture for southern Australian grazing systems where subterranean clover (Trifolium subterraneum L.) is the dominant annual pasture legume. This in vitro study to assess methanogenic potential examined how growth stage and cutting of biserrula affect biomass, nutritive value and fermentative parameters including methanogenic potential compared with subterranean clover. Both species were grown in a glasshouse, where three growth-stage treatments comprised plant collection at vegetative, reproductive or maturity growth stages. Three cutting (simulated grazing) treatments included cutting at the vegetative or reproductive stage and an uncut control, with herbage collection at maturity. Methane production in biserrula was unaffected by the stage of growth. Other nutritive value and fermentative parameters varied significantly with growth stage, the highest fibre content and lowest crude protein (CP) being found at maturity. Regrowth from herbage cut at the reproductive stage had higher CP and lower biomass than other cut treatments. In biserrula, this regrowth also showed the highest fermentability of the three cutting treatments including elevated methane yield. Notwithstanding these treatment effects on fermentability, biserrula maintained its strong anti-methanogenic advantage over subterranean clover across all treatments, confirming its potential as an anti-methanogenic bioactive pasture.

Sheep grazing bladder clover (Trifolium spumosum L.) had similar productivity and meat quality to sheep grazing subterranean clover (Trifolium subterraneum L.)

2013 ◽  
Vol 53 (3) ◽  
pp. 209 ◽  
Author(s):  
Hayley C. Norman ◽  
Angelo Loi ◽  
Matt G. Wilmot ◽  
Allan J. Rintoul ◽  
Bradley J. Nutt ◽  
...  
Keyword(s):  
Meat Quality ◽  
Animal Health ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Eating Quality ◽  
In Vitro Digestibility ◽  
Sheep Grazing ◽  
Daily Growth ◽  
Care Assessment

An accession of bladder clover, a new species to agriculture, was selected for commercial release in Australia with the cultivar name of AGWEST Bartolo. As part of a duty-of-care assessment, we tested the hypothesis that sheep grazing the bladder clover cultivar will have similar liveweight, condition scores and wool production to sheep grazing a widely adopted subterranean clover cultivar (cv. Dalkeith). Further, we hypothesised that sheep grazing bladder clover and subterranean clover will have similar meat quality (after 48 days of grazing) and health as indicated by muscle, liver and kidney panel analysis. The data supported the hypotheses. While there were significant initial differences in liveweight between the two groups of sheep, there were no significant differences in liveweight at later time points during the grazing period and no significant differences in mean daily growth rate between weighing times. There were no differences in wool growth between sheep grazing the bladder or subterranean clover cultivars. Sheep in the subterranean clover plots had significantly higher condition scores after the first 24 days of grazing; however, these differences were not apparent after another 24 days of grazing. There were some differences in indications of animal health; however, there were no significant detrimental effects associated with bladder clover and sheep grazing both species had mean plasma indicators that were deemed ‘healthy’. There were no differences in meat eating quality as estimated by a consumer panel for tenderness, juiciness or flavour. Dry seasonal conditions limited biomass growth and the sheep were removed from the subterranean clover plots on Day 48 of grazing. The sheep grazing the bladder clover plots remained on the plots for a further 26 days. The data indicate that, for the conditions of this experiment, the clovers had the same relative feeding value. Laboratory analysis of herbage from across the clover plots (bulked before analysis) suggest that the bladder clover had higher in vitro digestibility, crude protein and lower fibre than the herbage sample from the subterranean clover plots. The biomass data indicate that the bladder clover cultivar can support more grazing days per ha in a relatively dry season than the subterranean clover cultivar.

scholarly journals An Improved Protocol for Agrobacterium-Mediated Transformation in Subterranean Clover (Trifolium subterraneum L.)

2021 ◽  
Vol 22 (8) ◽  
pp. 4181
Author(s):  
Fernando Perez Rojo ◽  
Sumedha Seth ◽  
William Erskine ◽  
Parwinder Kaur
Keyword(s):  
Agrobacterium Tumefaciens ◽  
Nutritive Value ◽  
Transformation Efficiency ◽  
Incubation Temperature ◽  
Agronomic Traits ◽  
Genetic Manipulation ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Factors Affecting

Subterranean clover (Trifolium subterraneum) is the most widely grown annual pasture legume in southern Australia. With the advent of advanced sequencing and genome editing technologies, a simple and efficient gene transfer protocol mediated by Agrobacterium tumefaciens was developed to overcome the hurdle of genetic manipulation in subterranean clover. In vitro tissue culture and Agrobacterium transformation play a central role in testing the link between specific genes and agronomic traits. In this paper, we investigate a variety of factors affecting the transformation in subterranean clover to increase the transformation efficiency. In vitro culture was optimised by including cefotaxime during seed sterilisation and testing the best antibiotic concentration to select recombinant explants. The concentrations for the combination of antibiotics obtained were as follows: 40 mg L−1 hygromycin, 100 mg L−1 kanamycin and 200 mg L−1 cefotaxime. Additionally, 200 mg L−1 cefotaxime increased shoot regeneration by two-fold. Different plant hormone combinations were tested to analyse the best rooting media. Roots were obtained in a medium supplemented with 1.2 µM IAA. Plasmid pH35 containing a hygromycin-resistant gene and GUS gene was inoculated into the explants with Agrobacterium tumefaciens strain AGL0 for transformation. Overall, the transformation efficiency was improved from the 1% previously reported to 5.2%, tested at explant level with Cefotaxime showing a positive effect on shooting regeneration. Other variables in addition to antibiotic and hormone combinations such as bacterial OD, time of infection and incubation temperature may be further tested to enhance the transformation even more. This improved transformation study presents an opportunity to increase the feeding value, persistence, and nutritive value of the key Australian pasture.

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