Affiliation:
1. Mikrobiologisches Institut, Eidgen�ssische Technische Hochschule, ETH-Zentrum, CH-8092 Z�rich, Switzerland
Abstract
The phenotypes of a set of
Bradyrhizobium japonicum
110 mutants with large deletions in the region of symbiotic gene cluster I were tested. The majority of the mutants showed a delayed nodulation on soybean and, by mixed-infection experiments, were found to be strongly reduced in their competitiveness. Phenotypic comparison of mutants with different deletion endpoints allowed a preliminary localization of two genomic regions, called
nod-1
and
nod-2
, which were required for normal nodulation on soybean. Loss of
nod-1
was found to result in a Nod
−
phenotype on cowpea, mung bean, and siratro. A recombinant cosmid was identified which fully restored nodulation ability of a mutant lacking
nod-1
. Using Tn
5
-containing derivatives and subclones of this cosmid for complementation, we delimited the
nod-1
region to a DNA segment of 3.1 to 3.5 kilobase pairs.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
34 articles.
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