Signal transduction in the photocontrol of chalcone synthase gene expression*

Abstract

The pbotocontrol of cbalconc syntbase gene expression was studied by means of promoter analyses, in vitro systems, pbotoreceptor mutants and microinjections, and pbarmacological approaches. A 52 bp element of the promoter is necessary and sufficient to transfer lij»ht regulation. Chaicone synthase expression is primarily under the control of phyA and blue/lJV photoreceptors; the latter are functional even in the absence of phyA and phyB. Phytochromes seem to be soluble proteins and, within seconds of irradiation, light-dependent phosphorylations were observed in membrane-depleted cytosol preparations, indicating very early processes of signal transduction. Microinjection and pharmacological experiments reveal that, in the phyA pathway, heterotrinieric (J-proteins, edllVlP and a genistein-sensitive protein kinase are involved, whereas the UV pathway includes several trimerie G-proteins and Ca/calmodulindependent steps.

A BELL1-Like Gene of Potato Is Light Activated and Wound Inducible

“…Although there are examples where the minimal light-driven regulatory region on a promoter can be as short as 52 bp (Schafer et al, 1997;Martinez-Hernandez et al, 2002), several studies have confirmed that the minimal light-driven region is generally found within 250 bp upstream from the transcriptional start site (Terzaghi and Cashmore, 1995). Deletion analysis of the StBEL5 upstream region revealed that the construct containing 272 nucleotides of promoter plus 96 nucleotides of the 5#-UTR P2-StBEL5 was sufficient for light-mediated activation (Fig.…”

Proteomics-based dissection of stress-responsive pathways in plants

“…There is a no direct evidence for the signal that stimulates gene expression under UV stress; however, it appears that UV alters gene expression because of oxidative stress. Genes encoding enzymes of phenylpropanoid and flavonoid biosynthesis pathways [e.g., phenylalanine ammonia lyase (PAL) and chalcone synthase (CHS)] have been reported to stimulate by UV stress (Schafer et al, 1997). Products of these pathways are important in plant protection.…”

Direct Targeting of Light Signals to a Promoter Element-Bound Transcription Factor

“…These were the G-box-containing gene RBCS-IA (34) and CHS (Fig. 4, A and B) for which there is no evidence of a functionally active, fully palindromic G-box in Arabidopsis (22,35,36). On the other hand, the absence of the HY5 bZIP protein in the hy5 null mutant (37) caused no reduction in the photoresponsiveness of CCAI, W , or SPAI, but markedly reduced the induc-tion of CHS (Fig.…”