Cloning and characterization of a chalcone synthase gene from mustard and its light-dependent expression

Abstract

Genomic DNA from mustard was cloned in EMBL4 and screened for chalcone synthase (CHS) genes using a heterologous cDNA probe from parsley. Two clones which hybridized with the parsley cDNA probe were isolated. They showed different restriction patterns. One clone was sequenced and identified as a CHS gene by sequence comparison with published CHS sequences. The sequence of the coding region is 1188 bp, and encodes a protein of 43 kDa. The start-point of transcription was determined by primer extension. The sequence of 0.9 kbp at the 5' end of the transcription start and part of the noncoding 3' of this gene were also determined. The coding sequence is interrupted by a single intron of 523 bp. The coding and the noncoding 5' sequence of this gene was compared with CHS genes from other species. A very high homology was found with the Arabidopsis CHS coding region. A sequence motif (CACGTGT) which is present in most rbcS and all CHS upstream regions, and which specifically binds a protein factor from plant nuclear extracts, is also present in the upstream region of the mustard CHS gene. Measurements of CHS transcript levels show that phytochrome controls expression of this gene in cotyledons of mustard seedlings; however, blue/UV-light photoreceptors control expression in later stages of development.

Extension-growth responses and expression of flavonoid biosynthesis genes in the Arabidopsis hy4 mutant

“…It is well established that several plant genes are subject to regulation by blue light, separate from any control by phytochrome (Jenkins 1991;Kaufman 1993;Sawbridge et al 1994). The CHS gene is known to be controlled primarily by blue, UV-B and UV-A light in mature leaves of several plant species, including Sinapis (Batschauer et al 1991), parsley (Frohnmeyer et al 1992) and Arabidopsis (Feinbaum et al 1991;Kubasek et al 1992). Both DFR and CHI are also controlled by UV-B and UV-A/blue light in Arabidopsis (Kubasek et al 1992).…”

Differential usage of photoreceptors for chalcone synthase gene expression during plant development

“…In view of the findings of Ehmann et al (1991) that CHS mRNA accumulation in etiolated mustard seedlings is under the control of labile and stable phytochrome as well as the high irradiance reaction, 2-, 3-or 4-day-old etiolated mustard seedlings were irradiated for 12 h with red, farred, blue or UV-A light. Dot blot analyses using total RNA and a probe forthe entire CHScoding sequence indicated strong induction of CHS mRNA accumulation with far red and decreasingly weaker responses to red, blue and UV-A light (Figure 3).…”

“…The following probes were used for CHS mRNA detection: for parsley, a near full-length cDNA (LF15; Reimold etal., 1983) and for mustard a 748 bp fragment of the genomic clone SCHSl (Batschauer et a/., 1991) were labelled by Multiprime labelling system (Amersham) with p'P]dATP (Amersham; 11 0 TBq mmol-') according to the manufacturer's manual. Hybridization was performed as described by Ehmann eta/.…”

UV and blue light signal transduction in Arabidopsis

“…In mature leaves of several species, including Arabidopsis, CHS expression is regulated principally by UV and blue light, whereas in young or dark-grown seedlings, phytochrome is involved (Batschauer, Ehmann & Schafer 1991;Eeinbaum, Storz & Ausubel 1991;Frohnmeyer et al 1992;Fuglevand, Jackson & Jenkins 1996). In Arabidopsis, phytochrome regulation is confined to dark-grown seedlings less than 6 d old (Kaiser et al 1995) and phytochrome-deficient mutants retain the UV/blue light induction of CHS expression (Batschauer et al 1996).…”