Cyclic GMP acts as a common regulator for the transcriptional activation of the flavonoid biosynthetic pathway in soybean.
Cyclic GMP (cGMP) is an important signaling molecule that controls a range of cellular functions. So far, however, only a few genes have been found to be regulated by cGMP in higher plants. We investigated the cGMP-responsiveness of several genes encoding flavonoid-biosynthetic enzymes in soybean (Glycine max L.) involved in legume-specific isoflavone, phytoalexin and anthocyanin biosynthesis, such as phenylalanine ammonia-lyase, cinnamate 4-hydroxylase, 4-coumarate:CoA ligase, chalcone synthase, chalcone reductase, chalcone isomerase, 2-hydroxyisoflavanone synthase, 2-hydroxyisoflavanone dehydratase, anthocyanidin synthase, UDP-glucose:isoflavone 7-O-glucosyltransferase, and isoflavone reductase, and found that the majority of these genes were induced by cGMP but not by cAMP. All cGMP-induced genes were also stimulated by sodium nitroprusside (SNP), a nitric oxide (NO) donor, and illumination of cultured cells with white light. The NO-dependent induction of these genes was blocked by 6-anilino-5,8-quinolinedione, an inhibitor of guanylyl cyclase. Moreover, cGMP levels in cultured cells were transiently increased by SNP. Consistent with the increases of these transcripts, the accumulation of anthocyanin in response to cGMP, NO, and white light was observed. The treatment of soybean cotyledons with SNP resulted in a high accumulation of isoflavones such as daidzein and genistein. Loss- and gain-of-function experiments with the promoter of chalcone reductase gene indicated the Unit I-independent activation of gene expression by cGMP. Together, these results suggest that cGMP acts as a second messenger to activate the expression of genes for enzymes involved in the flavonoid biosynthetic pathway in soybean.
Suita
Kenji
K
Laboratory of Biochemistry, Graduate School of Agricultural Science, Kobe University, Rokkodai-cho 1-1, Nada-ku, Kobe, 657-8501, Japan.
Kiryu
Takaaki
T
Sawada
Maki
M
Mitsui
Maiko
M
Nakagawa
Masataka
M
Kanamaru
Kengo
K
Yamagata
Hiroshi
H
D000429:Alcohol Oxidoreductases / Q000235:genetics / Q000378:metabolism; D000872:Anthocyanins / Q000378:metabolism; D006152:Cyclic GMP / Q000378:metabolism*; D005419:Flavonoids / Q000096:biosynthesis*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000528:radiation effects; D017343:Genes, Plant; D007529:Isoflavones / Q000378:metabolism; D008027:Light; D008969:Molecular Sequence Data; D009569:Nitric Oxide / Q000378:metabolism; D009599:Nitroprusside / Q000494:pharmacology; D011401:Promoter Regions, Genetic / Q000235:genetics; D013025:Glycine max / Q000187:drug effects / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism*; D015533:Transcriptional Activation / Q000187:drug effects / Q000528:radiation effects
D000872:Anthocyanins; D005419:Flavonoids; D007529:Isoflavones; D009599:Nitroprusside; D009569:Nitric Oxide; D000429:Alcohol Oxidoreductases; C093070:chalcone reductase; D006152:Cyclic GMP