Linked Life Data

11467723

Source:http://linkedlifedata.com/resource/pubmed/id/11467723

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
6
pubmed:dateCreated
2001-7-24
pubmed:abstractText
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.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0008-4166
pubmed:author
pubmed:issnType
Print
pubmed:volume
47
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
475-87
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2001
pubmed:articleTitle
Erosion of root epidermal cell walls by Rhizobium polysaccharide-degrading enzymes as related to primary host infection in the Rhizobium-legume symbiosis.
pubmed:affiliation
Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing 48824, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, Non-P.H.S., Research Support, Non-U.S. Gov't