scholarly journals Morphogenesis of root nodules in white clover. I. Effective root nodules induced by the wild type Rhizobium leguminosarium biovar. trifolii

2014 ◽  
Vol 66 (3-4) ◽  
pp. 273-292 ◽  
Author(s):  
Barbara Łotocka ◽  
Joanna Kopcińska ◽  
Władysław Golinowski
Keyword(s):  
White Clover ◽  
Trifolium Repens ◽  
Rhizobium Leguminosarum ◽  
Root Nodules ◽  
Primary Root ◽  
Wild Type ◽  
Apical Position ◽  
Root Cortex ◽  
Vascular Tissues ◽  
Transverse Division

The research aimed at investigating the morphogenesis of cylindrical root nodules in <em>Trifolium repens</em> L. induced by the wild type <em>Rhizobium leguminosarum</em> biovar. <em>trifolii</em> strain 24. It has been demonstrated that the ontogenesis of a nodule begins with a transverse division of cells of the pericycle followed by the dedifferentiation and divisions of cells of the endodermis and inner layers of the primary root cortex. Shifting of the nodule meristem from its initially lateral to the apical position characteristic for cylindrical nodules was observed. Bacteroidal, cortical and vascular tissues of the nodule are described up to 42 days after inoculation. At that time typical degraded zone had not yet appeared in the nodules.

scholarly journals Morphogenesis of root nodules in white clover. II. The effect of mutation in genes nod IJ of the microsymbiont upon the nodule structure

2014 ◽  
Vol 67 (1) ◽  
pp. 5-22
Author(s):  
Barbara Łotocka ◽  
Joanna Kopcińska ◽  
Władysław Golinowski
Keyword(s):  
White Clover ◽  
Rhizobium Leguminosarum ◽  
Root Nodules ◽  
Single Cells ◽  
Wild Strain ◽  
Root Hairs ◽  
Nodule Development ◽  
Wild Type ◽  
Delayed Reaction ◽  
Infection Threads

Morphogenesis of ineffective root nodules initiated on the roots of white clover 'Astra' by the <em>Rhizobium leguminosarum</em> biovar. <em>trifolii</em> strains ANU261 (Tn5 insertion in nod 1 gene) and ANU262 (Tn5 insertion in nod J gene) was investigated. Following changes were observed, as compared to the wild-type nodulation: the exaggerated, not delayed reaction of root hairs; the delay in nodulation with the number of nodules the same as in plants inoculated with a wild strain; the formation and organization of the nodule primordium not changed in comparison with the wild-type nodules; infection threads abnormally branched and diffusing with bacteria deprived of light zone and enriched with storage material; infected cells of bacteroidal tissue abnormally strongly osmiophilic and only slightly vacuolated; symbiosomes with very narrowed peribacteroidal space, subject to premature degradation; abnormal accumulation of starch in the nodule tissues; nodule development blocked at the stage of laterally situated meristem and single nodule bundle; inhibition of divisions in the meristem and vacuolation of its cells; the appearance of single cells with colonies of saprophytic rhizobia embedded in the fibrillar matrix in the old, degraded regions of the bacteroidal tissue.

scholarly journals Development of Functional Symbiotic White Clover Root Hairs and Nodules Requires Tightly Regulated Production of Rhizobial Cellulase CelC2

2011 ◽  
Vol 24 (7) ◽  
pp. 798-807 ◽  
Author(s):  
Marta Robledo ◽  
José I. Jiménez-Zurdo ◽  
M. José Soto ◽  
Encarnación Velázquez ◽  
Frank Dazzo ◽  
...  
Keyword(s):  
Cell Wall ◽  
White Clover ◽  
Rhizobium Leguminosarum ◽  
Plant Cell Wall ◽  
Root Nodules ◽  
Root Hairs ◽  
Nitrogen Fixing ◽  
Plant Host ◽  
Root Cortex ◽  
Infection Threads

The establishment of rhizobia as nitrogen-fixing endosymbionts within legume root nodules requires the disruption of the plant cell wall to breach the host barrier at strategic infection sites in the root hair tip and at points of bacterial release from infection threads (IT) within the root cortex. We previously found that Rhizobium leguminosarum bv. trifolii uses its chromosomally encoded CelC2 cellulase to erode the noncrystalline wall at the apex of root hairs, thereby creating the primary portal of its entry into white clover roots. Here, we show that a recombinant derivative of R. leguminosarum bv. trifolii ANU843 that constitutively overproduces the CelC2 enzyme has increased competitiveness in occupying aberrant nodule-like root structures on clover that are inefficient in nitrogen fixation. This aberrant symbiotic phenotype involves an extensive uncontrolled degradation of the host cell walls restricted to the expected infection sites at tips of deformed root hairs and significantly enlarged infection droplets at termini of wider IT within the nodule infection zone. Furthermore, signs of elevated plant host defense as indicated by reactive oxygen species production in root tissues were more evident during infection by the recombinant strain than its wild-type parent. Our data further support the role of the rhizobial CelC2 cell wall–degrading enzyme in primary infection, and show evidence of its importance in secondary symbiotic infection and tight regulation of its production to establish an effective nitrogen-fixing root nodule symbiosis.

Specificity of association between Bacillus isolates and genotypes of Lolium perenne and Trifolium repens from a grass – legume pasture

1990 ◽  
Vol 68 (5) ◽  
pp. 1126-1130 ◽  
Author(s):  
C. P. Chanway ◽  
F. B. Holl ◽  
R. Turkington
Keyword(s):  
Lolium Perenne ◽  
Trifolium Repens ◽  
Rhizobium Leguminosarum ◽  
Root Nodules ◽  
Permanent Pasture ◽  
Trifolium Repens L ◽  
Shoot Weight ◽  
Genotypic Mixtures ◽  
Rhizobium Leguminosarum Biovar Trifolii ◽  
Pasture Plants

Specificity between plants and associated rhizosphere bacteria was investigated using species and genotypic mixtures of Lolium perenne L. (perennial ryegrass) and Trifolium repens L. (white clover) inoculated with Bacillus strains isolated from rhizosphere soil of the pasture plants. The genotypic identity of plants was controlled by using stolon tips (Trifolium) and tillers (Lolium) of three genotypes of each species collected from a 45-year-old permanent pasture. Inoculation of plants in the greenhouse with Bacillus isolates that had coexisted in the field with the Lolium component of a Lolium–Trifolium mixture increased Lolium root and shoot weight. Root and nodule weight of Trifolium in mixture regardless of its genotype was also higher when coexistent Bacillus–Lolium combinations were present. The presence of other coexistent Bacillus–plant or plant–plant combinations did not enhance performance of either pasture species. The identity of the Rhizobium leguminosarum biovar trifolii strains that formed Trifolium root nodules was unaffected by inoculation with Bacillus. Key words: Trifolium repens, Lolium perenne, Bacillus, specificity, rhizosphere, yield.

scholarly journals Morphogenesis of root nodules in white clover. III. The effect of mutation in nod IJ genes of the microsymbiont upon the DNA level in the host tissue

2014 ◽  
Vol 67 (1) ◽  
pp. 23-29
Author(s):  
Barbara Łotocka ◽  
Władysław Golinowski
Keyword(s):  
White Clover ◽  
Rhizobium Leguminosarum ◽  
Root Nodule ◽  
Nuclear Dna ◽  
Root Nodules ◽  
Root Hairs ◽  
Infection Threads ◽  
Dna Contents ◽  
Mutant Strains ◽  
Nuclear Dna Contents

On the basis of cytophotometric measurements a slightly increased DNA level in the nuclei of curled root hairs containing infection threads was observed in white clover inoculated with wild and mutant strains of <em>Rhizobium leguminosarum</em> biovar. <em>trifolii</em>, as compared to normal root hairs of te same plants. Cells of the root nodule primordia in 72 h after the inoculation, as compared to the root primary cortex, demonstrated an increased level of the nuclear DNA. No differences were observed in the nuclear DNA contents in individual layers of the cortex of the 28 day-old nodules. Generally it was low, varying from 2c to 4c. The meristematic and bacteroidal tissues in the effective nodules were characterized by a higher DNA level, as compared to the respective zones in ineffective nodules induced with the strains ANU261 (<em>nod I<sup>*</sup></em>) and ANU262 (<em>nod J<sup>*</sup></em>). The DNA level in the effective bacteroidal tissue varied from 4c to 32c, while in the tissue containing the strain ANU26l only the 2c-8c nuclei could be found and in the tissue with the strain ANU262 - the 4c-16c nuclei.

scholarly journals The LATD Gene of Medicago truncatula Is Required for Both Nodule and Root Development

2005 ◽  
Vol 18 (6) ◽  
pp. 521-532 ◽  
Author(s):  
Lydia J. Bright ◽  
Yan Liang ◽  
David M. Mitchell ◽  
Jeanne M. Harris
Keyword(s):  
Medicago Truncatula ◽  
Root Development ◽  
Sinorhizobium Meliloti ◽  
Root Nodules ◽  
Lateral Roots ◽  
Primary Root ◽  
Evolutionary Origin ◽  
Nodule Formation ◽  
Wild Type ◽  
Model Legume

The evolutionary origins of legume root nodules are largely unknown. We have identified a gene,LATD, of the model legume Medicago truncatula, that is required for both nodule and root development, suggesting that these two developmental processes may share a common evolutionary origin. The latd mutant plants initiate nodule formation but do not complete it, resulting in immature, non-nitrogen-fixing nodules. Similarly, lateral roots initiate, but remain shortstumps. The primary root, which initially appears to be wild type, gradually ceases growth and forms an abnormal tipthat resembles that of the mutant lateral roots. Infection by the rhizobial partner, Sinorhizobium meliloti, can occur, although infection is rarely completed. Once inside latd mutant nodules, S. meliloti fails to express rhizobial genes associatedwith the developmental transition from free-living bacterium to endosymbiont, such as bacA and nex38. The infecting rhizobia also fail to express nifH and fix nitrogen. Thus, both plant and bacterial development are blocked in latd mutant roots. Based on the latd mutant phenotype, we propose that the wild-type function of the LATD gene is to maintain root meristems. The strong requirement of both nodules and lateral roots for wild-type LATD gene function supports lateral roots as a possible evolutionary origin for legume nodules.

scholarly journals Trehalose Biosynthesis in Rhizobium leguminosarum bv. trifolii and Its Role in Desiccation Tolerance

2007 ◽  
Vol 73 (12) ◽  
pp. 3984-3992 ◽  
Author(s):  
Helen J. McIntyre ◽  
Holiday Davies ◽  
Timothy A. Hore ◽  
Simon H. Miller ◽  
Jean-Pierre Dufour ◽  
...  
Keyword(s):  
Desiccation Tolerance ◽  
Rhizobium Leguminosarum ◽  
De Novo ◽  
Root Nodules ◽  
Desiccation Stress ◽  
Nodule Occupancy ◽  
Wild Type ◽  
Breakdown Rates ◽  
Gene Expression Studies ◽  
Trehalose Accumulation

ABSTRACT Rhizobium leguminosarum bv. trifolii forms nitrogen-fixing root nodules on the pasture legume Trifolium repens, and T. repens seed is often coated with a compatible R. leguminosarum bv. trifolii strain prior to sowing. However, significant losses in bacterial viability occur during the seed-coating process and during storage of the coated seeds, most likely due to desiccation stress. The disaccharide trehalose is known to function as an osmoprotectant, and trehalose accumulation due to de novo biosynthesis is a common response to desiccation stress in bacteria. In this study we investigated the role of endogenous trehalose synthesis in desiccation tolerance in R. leguminosarum bv. trifolii strain NZP561. Strain NZP561 accumulated trehalose as it entered the stationary phase due to the combined actions of the TreYZ and OtsAB pathways. Mutants deficient in either pathway showed near-wild-type levels of trehalose accumulation, but double otsA treY mutants failed to accumulate any trehalose. The double mutants were more sensitive to the effects of drying, and their survival was impaired compared to that of the wild type when glass beads were coated with the organisms and stored at relative humidities of 5 and 32%. The otsA treY mutants were also less competitive for nodule occupancy. Gene expression studies showed that the otsA and treY genes were expressed constitutively and that expression was not influenced by the growth phase, suggesting that trehalose accumulation is controlled at the posttranscriptional level or by control of trehalose breakdown rates. Our results indicate that accumulated trehalose plays an important role in protecting R. leguminosarum bv. trifolii cells against desiccation stress and against stress encountered during nodulation.

THE PERFORMANCE OF S170 TALL FESCUE IN CANTERBURY

1974 ◽  
pp. 214-215
Author(s):  
B.R. Watkin
Keyword(s):  
New Zealand ◽  
White Clover ◽  
Tall Fescue ◽  
Trifolium Repens ◽  
Festuca Arundinacea ◽  
Sheep Grazing ◽  
Selection Of

AN Aberystwyth selection of tall fescue (Festuca arundinacea Schreb.), known as S170, was sown with certified New Zealand white clover (Trifolium repens) and re' clover (T. pratense) and compared under sheep grazing with other grass/clover pastures at the Grasslands Division Regional Station at Lincoln (Watkin, 1975) .

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