The effects of environmental and chemical signals on anthocyanin biosynthesis in non-chlorophyllous (white) corn leaves were investigated. Carbohydrates that caused the greatest stimulation of anthocyanin formation included fructose, glucose, and sucrose, followed by maltose, raffinose, trehalose, cellobiose, melibiose, galactose, and lactose. Sucrose enhanced the expression of anthocyanin biosynthesis genes on a transcriptional level. Carbohydrate concentration, duration of light exposure, and incubation temperature also had quantitative effects, low temperatures stimulated anthocyanin biosynthesis whereas water stress had no effect. Abscisic acid, jasmonic acid, and ethephon also enhanced anthocyanin accumulation, although the degree of its accumulation depended on co.supplied sucrose concentrations, and was relatively lower in white tissue than in green tissue. Gibberellic acids and 6-benzylaminopurine were significantly inhibitory at the nanomolar level. Indole 3-acetic acid and salicylic acid did not influence anthocyanin synthesis in the white tissue system. Diuron inhibited its formation only in green tissue. These results indicate that the white leaf segments of corn would be good systems for research on the signal networks related to chloroplast functioning in anthocyanin biosynthesis. Additionally, this experimental system could be practical for identifying hormone-like substances, especially gibberellic acids and benzylaminopurine.Keywords: anthocyanin biosynthesis, carbohydrates, environmental factors, non-chlorophyllous tissue, plant hormones, signal network Anthocyanins are the red, purple, and blue flavonoid pigments produced mainly in plant epidermal cells, where they accumulate in vacuoles, causing the tissue to become colored. The biochemical and genetic basis for anthocyanin production is relevant to both the development of neutroceutica[s, because of its antioxidant activity and resistance to environmental stress, and to its modification of flower colors (Mol et al., 1996;Chalker-Scott, 1999; WinkeI-Shirley, 2001;Kong et al., 2003). The anthocyanin biosynthetic pathway has been studied intensively. Expression of the genes involved is regulated by a complex array of environmental and developmental signals, such as light quality, temperature, plant hormones, and sugars (Mo Chalker-Scott, 1999; WinkeI-Shirley, 2001). Some of these signals promote the activity of master transcription regulators that control various secondary metabolic pathways (Endt et al., 2002). Negative regulators of anthocyanin biosynthesis also have been reported (Aharoni et al., 2001;Wade et al., 2003). Nevertheless, although the physiology and basic genetics of the anthocyanin biosynthetic pathway are well characterized, an integrated understand-*Corresponding author; fax +82-42-861-4913 e-mail jskim@krict.re.kr ing of the regulatory network is still elementary. Park et al. (1998) have reported that anthocyanin formation is accelerated by sucrose supplementation to a greater extent in non-chlorophyllous (white) leaf segment...
