A light-independent developmental mechanism potentiates flavonoid gene expression in Arabidopsis seedlings |
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Authors: | Kubasek William L Ausubel Frederick M Shirley Brenda Winkel |
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Institution: | (1) Department of Genetics, Harvard Medical School and Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, 02114, pUSA;(2) Department of Biology, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061-0406, USA;(3) Present address: Praecis Pharmaceuticals, Inc., 1 Hampshire, St., Cambridge, MA 02139, USA |
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Abstract: | Throughout the plant kingdom expression of the flavonoid biosynthetic pathway is precisely regulated in response to developmental signals, nutrient status, and environmental stimuli such as light, heat and pathogen attack. Previously we showed that, in developing Arabidopsis seedlings, flavonoid genes are transiently expressed during germination in a light-dependent manner, with maximal mRNA levels occurring in 3-day-old seedlings. Here we describe the relationship between developmental and environmental regulation of flavonoid biosynthesis by examining phenylalanine ammonia-lyase (PAL), chalcone synthase (CHS), chalcone isomerase (CHI), and dihydroflavonol reductase (DFR) mRNA levels in germinating Arabidopsis seedlings as a function of light, developmental stage and temperature. We show that seedlings exhibit a transient potential for induction of these four genes, which is distinct from that observed for chlorophyll a/b-binding protein (CAB). The potential for flavonoid gene induction was similar in seedlings grown in darkness and red light, indicating that induction potential is not linked to cotyledon expansion or the development of photosynthetic capacity. The evidence for metabolic regulation of flavonoid genes during seedling development is discussed. |
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Keywords: | Arabidopsis flavonoid seedling development phenylalanine ammonia-lyase chalcone synthase chalcone isomerase dihydroflavonol reductase |
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