Arabidopsis ICX1 Is a Negative Regulator of Several Pathways Regulating Flavonoid Biosynthesis Genes1

• Published in: Plant physiology (Bethesda) Vol. 131; no. 2; pp. 707 - 715
• Main Authors: Wade, Helena K., Sohal, Awinder K., Jenkins, Gareth I.
• Format: Journal Article
• Language: English
• Published: American Society of Plant Biologists 01.02.2003
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.012377

Flavonoid biosynthesis gene expression is controlled by a range of endogenous and environmental signals. The Arabidopsis icx1 ( increased chalcone synthase expression 1 ) mutant has elevated induction of CHS ( CHALCONE SYNTHASE ) and other flavonoid biosynthesis genes in response to several stimuli. We show that ICX1 is a negative regulator of the cryptochrome 1, phytochrome A, ultraviolet (UV)-B, low temperature, sucrose, and cytokinin induction of CHS expression and/or anthocyanin accumulation, demonstrating that these pathways are regulated either directly or indirectly by at least one common component. Expression analysis of CHS and other genes ( LTP , CAB , and rbcS ) indicates that ICX1 functions in both seedlings and mature leaf tissue and acts principally in the epidermis, consistent with the alterations in epidermal development seen in icx1 . The mutant was unaltered in the synergistic interactions between UV-B, blue, and UV-A light that regulate CHS and we propose a model of action of ICX1 in these responses.