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Rhizobia form specialized nodules on the roots of legumes (family Fabaceae) and fix nitrogen in exchange for carbon from the host plant. Although the majority of legumes form symbioses with members of genus Rhizobium and its relatives in class Alphaproteobacteria, some legumes, such as those in the large genus Mimosa, are nodulated predominantly by(More)
Based on partial 16S sequences, we previously described a novel group of nonsymbiotic, acetylene reduction activity-positive actinomycetes which were isolated from surface-sterilized roots of Casuarina equisetifolia growing in Mexico. An amplified rRNA restriction analysis confirmed that these actinomycetes are distinct from Frankia, a finding substantiated(More)
PsUGT1, which encodes a microsomal UDP-glucuronosyltransferase, was cloned from root tips of Pisum sativum. PsUGT1 expression is correlated with mitosis and strongly induced in dividing cells. A region at the C terminus of the encoded protein is closely related to the UDP-glucuronic acid binding site consensus sequence, and the protein encoded by PsUGT1(More)
Spontaneous mutants at a new symbiotic locus in Rhizobium meliloti SU47 are resistant to several phages and are conditionally insensitive to a monoclonal antibody to the bacterial surface, apparently because they are deficient in a wild-type exopolysaccharide. On alfalfa, the mutants do not curl root hairs, but penetrate the epidermis directly, forming(More)
ENOD40, an early nodulin gene, is expressed following inoculation with Rhizobium meliloti or by adding R. meliloti-produced nodulation (Nod) factors or the plant hormone cytokinin to uninoculated roots. We isolated two MsENOD40 clones, designated MsENOD40-1 and MsENOD40-2, with distinct promoters from an alfalfa (Medicago sativa cv Chief) genomic library.(More)
Plant lectins have been implicated as playing an important role in mediating recognition and specificity in the Rhizo-bium –legume nitrogen-fixing symbiosis. To test this hypothesis, we introduced the soybean lectin gene Le1 either behind its own promoter or behind the cauliflower mosaic virus 35S promoter into Lotus corniculatus , which is nodu-lated by R.(More)
Treatment of Pisum sativum (L.) cv. ;Sparkle' with ethyl methanesulfonic acid (EMS) produced a stable mutant, E135F, which forms small, white, ineffective nodules. These nodules exhibit histological zonation typical of an indeterminant nodule, e.g. meristematic, early symbiotic, late symbiotic, and senescent zones. Compared with the nitrogen fixing nodules(More)
Rhizobium nod genes are essential for root hair deformation and cortical cell division, early stages in the development of nitrogen-fixing root nodules. Nod(-) mutants are unable to initiate nodules on legume roots. We observed that N-(1-naphthyl)phthalamic acid and 2,3,5-triiodobenzoic acid, compounds known to function as auxin transport inhibitors,(More)
Burkholderia is a diverse and dynamic genus, containing pathogenic species as well as species that form complex interactions with plants. Pathogenic strains, such as B. pseudomallei and B. mallei, can cause serious disease in mammals, while other Burkholderia strains are opportunistic pathogens, infecting humans or animals with a compromised immune system.(More)
Rhizobia are non-spore-forming soil bacteria that fix atmospheric nitrogen into ammonia in a symbiosis with legume roots. However, in the absence of a legume host, rhizobia manage to survive and hence must have evolved strategies to adapt to diverse environmental conditions. The capacity to respond to variations in nutrient availability enables the(More)