Flower differentiation in arabidopsis
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There is a consensus among developmental geneticists that few generalizations are possible at the present status of the field, and even the boundaries are difficult to define. Yet in few special cases, consistent facts have been accumulated which point to systems of controls of differentiation.In the facultative long-day plant Arabidopsis, the differentiation of flower primordia is controlled by several gene loci. Recessive mutations may determine in a qualitatively distinct manner the onset of flower development. Continuous illumination in contrast to 8-9 hours daily cycles of light promotes flowering in all genotypes. Mutants at the ld locus are incapable of flowering under short days and entail a critical day-length. Different alleles at the gi locus require several times as long period for flower induction than the wild type under 24 hours light yet under short days they do not differ, very conspicuously from the standard type. Mutants at the co locus are late flowering and recessive under long days but they are more precocious than the wild type under short days and they display dominance. In total darkness, the wild type and all mutants flower early. The aseptic feeding of 5-bromodeoxyuridine highly accelerates flower differentiation in all genotypes under long days and also under short days with the exception of the ld mutants. The analog is incorporated into the DNA of all types. Bromodeoxyuridine-grown plants accumulate higher amounts of radioactivity, provided by 14[subscript C]-amino acids, into a chromatin fraction. The experimental observations support the view that flowering in this plant is under negative control and bromodeoxyuridineis hampering the synthesis of a postulated suppressor.