Symbiotic and genetic diversity of Rhizobium galegae isolates collected from the Galega orientalis gene center in the Caucasus. (1/4)

This paper explores the relationship between the genetic diversity of rhizobia and the morphological diversity of their plant hosts. Rhizobium galegae strains were isolated from nodules of wild Galega orientalis and Galega officinalis in the Caucasus, the center of origin for G. orientalis. All 101 isolates were characterized by genomic amplified fragment length polymorphism fingerprinting and by PCR-restriction fragment length polymorphism (RFLP) of the rRNA intergenic spacer and of five parts of the symbiotic region adjacent to nod box sequences. By all criteria, the R. galegae bv. officinalis and R. galegae bv. orientalis strains form distinct clusters. The nod box regions are highly conserved among strains belonging to each of the two biovars but differ structurally to various degrees between the biovars. The findings suggest varying evolutionary pressures in different parts of the symbiotic genome of closely related R. galegae biovars. Sixteen R. galegae bv. orientalis strains harbored copies of the same insertion sequence element; all were isolated from a particular site and belonged to a limited range of chromosomal genotypes. In all analyses, the Caucasian R. galegae bv. orientalis strains were more diverse than R. galegae bv. officinalis strains, in accordance with the gene center theory.  (+info)

Mechanisms underlying the metabolic actions of galegine that contribute to weight loss in mice. (2/4)

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Isolation and characterization of GoRAV, a novel gene encoding a RAV-type protein in Galegae orientalis. (3/4)

RAV is a unique transcription factor in higher plants with AP2 and B3-like two distinct DNA-binding domains, but its roles in plant growth and development remains unknown. We have isolated a novel RAV family gene from Galegae orientalis, called GoRAV, which responds to cold induction. Sequence alignment showed that it shares high identity with other RAV family members in AP2 and B3 domain. Transient expression analysis using onion epidermal cells indicated that GoRAV protein is localized in the nucleus. Semi-quantitative RT-PCR (S-Q RT-PCR) analysis indicated that GoRAV is induced by cold, dehydration, high-salinity and abscisic acid, with the strongest induction in G. orientalis leaves during the early response to abiotic elicitors. GoRAV is more abundant in leaf than in stem, but is not expressed in root. This work adds a new member to the RAV family.  (+info)

Isolation and characterization of GoDREB encoding an ERF-type protein in forage legume Galegae orientalis. (4/4)

ERF is a unique transcription factor in higher plants with AP2-like DNA-binding domains. An ERF-like gene was isolated from Galegae orientalis, termed GoDREB. Sequence alignment showed that it shares high identity with other ERF family members in AP2 domain. Transient expression analysis indicated that GoDREB protein is localized in the nucleus. Quantitative RT-PCR analysis results showed that GoDREB is induced by a variety of abiotic stress, such as cold, dehydration, and high-salinity. Exogenous hormones, such as methyl jasmonate acid and salicylic acid, also up-regulate the expression of GoDREB. However, ABA did not induce the mRNA accumulation of GoDREB. These results implied that the GoDREB might play a role in these two hormones-dependent but not be involved in the ABA-dependent stress signaling pathway. Overexpression of GoDREB in transgenic tobacco plants resulted in higher tolerance to high salinity, osmotic and low-temperature stresses. These results suggest that GoDREB may play an essential role as an ERF transcription factor in regulation of stress-responsive signaling in G. orientalis.  (+info)