ABSTRACT
Light regulates various aspects of plant growth, and the photoreceptor phytochrome B (phyB) mediates many responses to red light. In a screen for Arabidopsis mutants with phenotypes similar to those of phyB mutants, we isolated two new elf3 mutants. One has weaker morphological phenotypes than previously identified elf3 alleles, but still abolishes circadian rhythms under continuous light. Like phyB mutants, elf3 mutants have elongated hypocotyls and petioles, flower early, and have defects in the red light response. However, we found that elf3 mutations have an additive interaction with a phyB null mutation, with phyA or hy4 null mutations, or with a PHYB overexpression construct, and that an elf3 mutation does not prevent nuclear localization of phyB. These results suggest that either there is substantial redundancy in phyB and elf3 function, or the two genes regulate distinct signaling pathways.
Subject(s)
Hypocotyl/physiology , Photoreceptor Cells , Photosynthetic Reaction Center Complex Proteins , Phytochrome/physiology , Plant Proteins/physiology , Transcription Factors , Base Sequence , DNA Primers , Mutation , Phenotype , Phytochrome/genetics , Phytochrome B , Plant Proteins/genetics , Plants, Genetically Modified/genetics , Plants, Genetically Modified/physiologyABSTRACT
Ambient light controls the development and physiology of plants. The Arabidopsis thaliana photoreceptor phytochrome B (PHYB) regulates developmental light responses at both seedling and adult stages. To identify genes that mediate control of development by light, we screened for suppressors of the long hypocotyl phenotype caused by a phyB mutation. Genetic analyses show that the shy (short hypocotyl) mutations we have isolated fall in several loci. Phenotypes of the mutants suggest that some of the genes identified have functions in control of light responses. Other loci specifically affect cell elongation or expansion.
Subject(s)
Arabidopsis/genetics , Arabidopsis/physiology , Genes, Plant , Mutagenesis , Photoreceptor Cells , Phytochrome/genetics , Plant Proteins/genetics , Transcription Factors , Arabidopsis Proteins , Darkness , Hypocotyl , Light , Phenotype , Phytochrome B , Plant Roots/physiology , Time FactorsABSTRACT
Fifteen strains of Burkholderia (Pseudomonas) solanacearum were isolated, identified from different parts of India and screened for plasmid profile. They harboured 1-3 plasmids, but most of the isolates contained a single plasmid. Plasmids were classified on the basis of replicon typing by Southern hybridization using incompatible specific rep probes. Plasmids of 9 strains hybridized with repP probe, plasmids of 5 strains hybridized with repW probe and one plasmid hybridized with repQ probe. Fingerprint and cluster analyses of plasmids from 10 strains of B. solanacearum digested with Eco RI revealed that plasmids of race 3 strains clustered in one group and the plasmids of race 1 strains clustered in another group.
