The role of the COP/DET/FUS genes in light control of Arabidopsis seedling development

• Published in: Plant physiology (Bethesda) Vol. 112; no. 3; pp. 871 - 878
• Main Authors: Wei, N. (Yale University, New Haven, CT.), Deng, X.W
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Physiologists 01.11.1996
• Subjects: AHILAMIENTO; Arabidopsis - genetics; Arabidopsis - physiology; Arabidopsis - radiation effects; ARABIDOPSIS THALIANA; Biological and medical sciences; DARKNESS; Developmental biology; DNA BINDING MOTIFS; ETIOLATION; ETIOLEMENT; EXPRESION GENICA; EXPRESSION DES GENES; FENOTIPOS; FOTORECEPTORES; Fundamental and applied biological sciences. Psychology; GENE; GENE EXPRESSION; Gene Expression Regulation, Plant - radiation effects; GENE INTERACTION; GENES; Genes, Plant; Genes, Regulator; Genetic loci; Genetic mutation; GENETIC REGULATION; GENETICA; GENETICS; GENETIQUE; Hypocotyls; INHIBITOR GENES; INTERACCION DE GENES; INTERACTION GENIQUE; LIGHT; LUMIERE; LUZ; MORFOGENESIS; MORPHOGENESE; MORPHOGENESIS; MUTANT; MUTANTES; MUTANTS; Mutation; OBSCURIDAD; OBSCURITE; PHENOTYPE; PHENOTYPES; PHOTORECEPTEUR; PHOTORECEPTORS; Physical agents; Plant cells; Plant physiology and development; Plants; PLANTULAS; PLANTULE; PLEIOTROPY; Proteins; SEEDLINGS; Update on Development; Vegetative apparatus, growth and morphogenesis. Senescence; Regulation(control); Vegetals; Light; Development; Genetics; Review; Mutation
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.112.3.871

Light is vital to plant life, not only as an energy source for photosynthesis but also as an important environmental signal regulating development and growth. Light affects almost every stage of plant development, including seedling development, which represents one of the most dramatic and best characterized processes. In Arabidopsis thaliana, for example, the morphology of the embryo in the imbibing seed (d 1), as well as the emerging seedling from the seed coat (d 2), are minimally affected by light conditions. Soon after, however, seedling morphogenesis differs drastically, depending on the light environment. Light-grown seedlings exhibit short hypocotyls and open and expanded cotyledons. Cell-type differentiation and chloroplast development are soon established, and photosynthetically related genes are highly expressed. The shoot apical meristem is activated to produce true leaves and the plants proceed with further vegetative and reproductive growth soon thereafter. This development pattern in light is known as photomorphogenesis. In contrast, when seedlings are grown in complete darkness, they undergo a developmental program known as skotomorphogenesis or etiolation, in which the cotyledons remain folded and undeveloped, while the hypocotyls rapidly elongate. The apical hook serves to protect cotyledons and the quiescent shoot meristems as the seedling elongates rapidly to reach for the light. Instead of developing chloroplasts, the cotyledon cells form etioplasts that can readily convert into chloroplasts when exposed to light. This process is known as greening or de-etiolation. In addition, etiolated seedlings display a very different gene expression pattern from that determined by light. After the initial elongating growth, the seedlings come to a developmental arrest in the continuous absence of light. In higher plants, light-controlled physiological and developmental responses are mediated through at least three families of photoreceptors: phytochromes, cryptochromes, or blue-light receptors, and UV-B receptors, depending on the wavelengths of light to which they are most sensitive. In Arabidopsis, genes for five phytochromes, phytochrome A, B, C, D, and E, and a blue-light receptor, CRY1 (or HY4), have been isolated. Recent reviews of the photobiology and molecular biology of photoreceptor action have been published. In this Update we will emphasize the role of a group of negative regulators genetically identified as constitutive photomorphogenic (COP) or de-etiolated (DET) loci.