Cytokinins enhance sugar-induced anthocyanin biosynthesis in Arabidopsis.
In higher plants, the regulation of anthocyanin synthesis by various factors including light, sugars and hormones is mediated by numerous regulatory factors acting at the transcriptional level. Here, the association between sucrose and the plant hormone, cytokinin, in the presence of light was investigated to elucidate cytokinin signaling cascades leading to the transcriptional activation of anthocyanin biosynthesis genes in Arabidopsis seedlings. We showed that cytokinin enhances anthocyanin content and transcript levels of sugar inducible structural gene UDPglucose: flavonoid 3-O-glucosyl transferase (UF3GT) and regulatory gene PRODUCTION OF ANTHOCYANIN PIGMENT 1 (PAP1). Genetic analysis showed that cytokinin signaling modulates sugar-induced anthocyanin biosynthesis through a two-component signaling cascade involving the type-B response regulators ARR1, ARR10 and ARR12 in a redundant manner. Genetic, physiological and molecular biological approaches demonstrated that cytokinin enhancement is partially dependent on phytochrome and cryptochrome downstream component HY5, but mainly on photosynthetic electron transport. Taken together, we suggest that cytokinin acts down-stream of the photosynthetic electron transport chain in which the plastoquinone redox poise is modulated by sugars in a photoreceptor independent manner.
Department of Biological Sciences, College of Biological Science and Biotechnology, Chungnam National University, Daejeon 305-764, Korea.
Prasanta Kumar
PK
Das
Dong Ho
DH
Shin
Sang-Bong
SB
Choi
Sang-Dong
SD
Yoo
Giltsu
G
Choi
Youn-Il
YI
Park
D000872:Anthocyanins / Q000096:biosynthesis*; D017360:Arabidopsis / Q000378:metabolism* / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism; D050976:Basic-Leucine Zipper Transcription Factors / Q000378:metabolism; D003583:Cytokinins / Q000494:pharmacology / Q000502:physiology*; D005700:Galactosyltransferases / Q000235:genetics* / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D009687:Nuclear Proteins / Q000378:metabolism; D010084:Oxidation-Reduction; D000073718:Pancreatitis-Associated Proteins; D010858:Pigmentation; D036226:Seedlings / Q000378:metabolism / Q000528:radiation effects; D015398:Signal Transduction; D013395:Sucrose / Q000378:metabolism*; D015534:Trans-Activators / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic; D015533:Transcriptional Activation
D000872:Anthocyanins; D029681:Arabidopsis Proteins; D051792:Basic Helix-Loop-Helix Proteins; D050976:Basic-Leucine Zipper Transcription Factors; D003583:Cytokinins; D005700:Galactosyltransferases; D009687:Nuclear Proteins; D000073718:Pancreatitis-Associated Proteins; D013395:Sucrose; D015534:Trans-Activators; D014157:Transcription Factors; C109254:HY5 protein, Arabidopsis; C502612:AT1G56650 protein, Arabidopsis; C116162:PIF3 protein, Arabidopsis; C000612141:REG3A protein, human; C117137:UDP-galactose flavonoid 3-O-galactosyltransferase