Specific Enhancement of Clover Root Hair Infections by Trifoliin A-Binding Lipopolysaccharide from Rhizobium Trifolii

1984 ◽  
pp. 413-413 ◽  
Author(s):  
F. B. Dazzo ◽  
G. L. Truchet ◽  
E. M. Hrabak
Keyword(s):  
Root Hair ◽  
Rhizobium Trifolii ◽  
Specific Enhancement ◽  
Clover Root

Erosion of root epidermal cell walls by Rhizobium polysaccharide-degrading enzymes as related to primary host infection in the Rhizobium–legume symbiosis

2001 ◽  
Vol 47 (6) ◽  
pp. 475-487
Author(s):  
Pedro F Mateos ◽  
David L Baker ◽  
Maureen Petersen ◽  
Encarna Velázquez ◽  
José I Jiménez-Zurdo ◽  
...  
Keyword(s):  
Cell Wall ◽  
Root Hair ◽  
Nod Factors ◽  
Wild Type ◽  
Primary Host ◽  
Degrading Enzymes ◽  
Clover Root ◽  
Host Cell Wall ◽  
Legume Symbiosis ◽  
Host Infection

A central event of the infection process in the Rhizobium–legume symbiosis is the modification of the host cell wall barrier to form a portal of entry large enough for bacterial penetration. Transmission electron microscopy (TEM) indicates that rhizobia enter the legume root hair through a completely eroded hole that is slightly larger than the bacterial cell and is presumably created by localized enzymatic hydrolysis of the host cell wall. In this study, we have used microscopy and enzymology to further clarify how rhizobia modify root epidermal cell walls to shed new light on the mechanism of primary host infection in the Rhizobium–legume symbiosis. Quantitative scanning electron microscopy indicated that the incidence of highly localized, partially eroded pits on legume root epidermal walls that follow the contour of the rhizobial cell was higher in host than in nonhost legume combinations, was inhibited by high nitrate supply, and was not induced by immobilized wild-type chitolipooligosaccharide Nod factors reversibly adsorbed to latex beads. TEM examination of these partially eroded, epidermal pits indicated that the amorphous, noncrystalline portions of the wall were disrupted, whereas the crystalline portions remained ultrastructurally intact. Further studies using phase-contrast and polarized light microscopy indicated that (i) the structural integrity of clover root hair walls is dependent on wall polymers that are valid substrates for cell-bound polysaccharide-degrading enzymes from rhizobia, (ii) the major site where these rhizobial enzymes can completely erode the root hair wall is highly localized at the isotropic, noncrystalline apex of the root hair tip, and (iii) the degradability of clover root hair walls by rhizobial polysaccharide-degrading enzymes is enhanced by modifications induced during growth in the presence of chitolipooligosaccharide Nod factors from wild-type clover rhizobia. The results suggest a complementary role of rhizobial cell-bound glycanases and chitolipooligosaccharides in creating the localized portals of entry for successful primary host infection.Key words: Rhizobium leguminosarum, cellulase, cell wall, chitolipooligosaccharide, clover, root hair.

scholarly journals The Isolation and Partial Characterization of the Lipopolysaccharides from Several Rhizobium trifolii Mutants Affected in Root Hair Infection

1987 ◽  
Vol 84 (2) ◽  
pp. 421-427 ◽  
Author(s):  
Russell W. Carlson ◽  
Robert Shatters ◽  
Jauh-Lin Duh ◽  
Elroy Turnbull ◽  
Brian Hanley ◽  
...  
Keyword(s):  
Root Hair ◽  
Partial Characterization ◽  
Rhizobium Trifolii ◽  
Root Hair Infection

Nodulation of subterranean clover growing in permanent pastures on acid soils in North-Central Victoria

1986 ◽  
Vol 26 (1) ◽  
pp. 31 ◽  
Author(s):  
HR Jones ◽  
BC Curnow
Keyword(s):  
Root Rot ◽  
Acid Soils ◽  
Subterranean Clover ◽  
Rhizobium Trifolii ◽  
Soil Factors ◽  
North Central ◽  
Exchangeable Calcium ◽  
Central Victoria ◽  
Clover Root

A survey ofclover at 44 sites in permanent dryland pastures in North-Central Victoria, highlighted poor nodulation of subterranean clover.In 1982 and 1983 respectively only 40 and 62% of plants were effectively nodulated 8-10 weeks after germination of the clover. Clover root rot was also present in both years, 64% of plants being affected in 1982 and 14% in 1983. Nodulation was negatively correlated with the incidence of root rot and with the percentage of exchangeable aluminium in the soil and positively correlated with the percentage of exchangeable calcium in the soil. The number of Rhizobium trifolii in the soil was not correlated with any of the soil factors measured.

scholarly journals The sensitivity of white clover root hairs to aluminium

1996 ◽  
Vol 6 ◽  
pp. 137-140
Author(s):  
D.A. Care
Keyword(s):  
White Clover ◽  
Root Hair ◽  
Root Hairs ◽  
Aluminium Tolerance ◽  
Hair Length ◽  
Pastoral Systems ◽  
Root Hair Length ◽  
Clover Root ◽  
Low Ionic Strength ◽  
Two Populations

Two populations of white clover, selected for long (L) and short (S) root hairs from the cultivar Tamar, were used to determine the root hair response curve to a range of aluminium (Al) concentrations similar to those found under field conditions. Seeds from the L and S populations were germinated and grown in low ionic strength hydroponic culture. Al was added to give final concentrations of 0, 2.5, 5, 7.5 and 10 ìM Al in solution. After 4 weeks plants were harvested and subsampled for root hair analysis. Mean root hair length, root hair number and total root hair length were recorded. Mean root hair length decreased by about 30% at 2.5 ìM Al, and by 70% at 10 ìM Al, but the most Al sensitive parameter was root hair number. Root hair numbers decreased by 70% at only 2.5 ìM Al, and at 10 ìM Al, had decreased by 99%. This pruning effect on total root hair length and number has major implications for the root hair functions of nutrient acquisition, preserving the moisture film, anchorage and nodulation. These are discussed in relation to New Zealand pastoral systems. Keywords: aluminium tolerance, nodulation, root hairs, root pulling, Trifolium repens L., white clover

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