Study of the basis for the competitiveness of Rhizobium japonicum in the nodulation of soybean

Technical Report · Fri Jun 01 04:00:00 EDT 1990

OSTI ID:5957018

Bauer, W

The overall goal of our studies was to identify cellular and molecular characteristics of rhizobia that are important to root colonization and symbiotic infection in competition with indigenous soil microbes. Rhizobia were found to respond to specific host flavonoids as chemoattractants as well as nodulation gene inducers. Motility and chemotaxis contributed significantly to the efficiency of symbiotic interactions, but not to colonization of root tips, where bacterial dispersal depended primarily on passive movement by root cell elongation. Co-inoculation of Rhizobium nod gene mutants with each other and with the wild-type showed that the mutants could help the wild-type, but not each other, to initiate nodules. Mutants with defective host specificity genes were the only ones capable of helping the wild-type in an additive or synergistic manner. Alfalfa was shown to have rapid, systemic feedback regulation suppressing nodule formation in younger parts of the root system in response to initiation of the first nodules. Root mucilage and exudate components were found to affect attachment of rhizobia to root surfaces. Methods for optimal surface sterilization of legume seeds were examined. 5 refs.

• Research Organization: Ohio State Univ., Columbus, OH (USA). Dept. of Agronomy
• Sponsoring Organization: DOE; USDOE, Washington, DC (USA)
• DOE Contract Number: FG02-86ER13522
• OSTI ID: 5957018
• Report Number(s): DOE/ER/13522-4; ON: DE91010704
• Country of Publication: United States
• Language: English

Related Subjects

550700 -- Microbiology
553006* -- Agriculture & Food Technology-- Other Agricultural Applications-- (1987-)
59 BASIC BIOLOGICAL SCIENCES
60 APPLIED LIFE SCIENCES
ABSORPTION
ALFALFA
BACTERIA
BIOFLAVONOIDS
CHEMORECEPTORS
COLONY FORMATION
DOCUMENT TYPES
INFECTIVITY
INHIBITION
LEGUMINOSAE
MAGNOLIOPHYTA
MAGNOLIOPSIDA
MICROORGANISMS
MYCORRHIZAS
NITROGEN FIXATION
PLANTS
PROGRESS REPORT
RESPONSE MODIFYING FACTORS
RHIZOBIUM
ROOT ABSORPTION
SYMBIOSIS
UPTAKE
VITAMINS