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HERO ID
3318143
Reference Type
Journal Article
Title
Infection and invasion of roots by symbiotic, nitrogen-fixing rhizobia during nodulation of temperate legumes
Author(s)
Gage, DJ
Year
2004
Is Peer Reviewed?
1
Journal
Microbiology and Molecular Biology Reviews
ISSN:
1092-2172
EISSN:
1098-5557
Publisher
AMER SOC MICROBIOLOGY
Location
WASHINGTON
Volume
68
Issue
2
Page Numbers
280-+
PMID
15187185
DOI
10.1128/MMBR.68.2.280-300.2004
Web of Science Id
WOS:000222077500006
Abstract
Bacteria belonging to the genera Rhizobium, Mesorhizobium, Sinorhizobium, Bradyrhizobium. and Azorhizobium (collectively referred to as rhizobia) grow in the soil as free-living organisms but can also live as nitrogen-fixing symbionts inside root nodule cells of legume plants. The interactions between several rhizobial species and their host plants have become models for this type of nitrogen-fixing symbiosis. Temperate legumes such as alfalfa, pea, and vetch form indeterminate nodules that arise from root inner and middle cortical cells and grow out from the root via a persistent meristem. During the formation of functional indeterminate nodules, symbiotic bacteria must gain access to the interior of the host root. To a from the outside to the inside, rhizobia grow and divide in tubules called infection threads, which are composite structures derived from the two symbiotic partners. This review focuses oil symbiotic infection and invasion during the formation of indeterminate nodules. It summarizes root hair growth, how root hair growth is influenced by rhizobial signaling molecules, infection of root hairs, infection thread extension down root hairs, infection thread growth into root tissue, and the plant and bacterial contributions necessary for infection thread formation and growth. The review also summarizes recent advances concerning the growth dynamics of rhizobial populations in infection threads.
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