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  • 1
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Recently strategies have been developed to mimic mutations by reducing gene expression using RNA that contains the complementary sequence to a given RNA, and hence is termed anti-sense RNA.2"7 This approach has shown that the activity of introduced genes encoding nopaline synthase6 and ...
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  • 2
    ISSN: 1573-5028
    Keywords: Key words ; antisense RNA ; β-glucuronidase ; protoplasts ; transient gene expression ; PCR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Antisense RNA-mediated inhibition of gene expression is a valuable tool to induce mutant phenotypes. We are interested in the application of antisense gene fragments with the aim to improve the efficiency of inhibition and to be able to selectively suppress gene family members in plants. Protoplasts may provide a rapid system to screen the efficiency of antisense gene segments. As a first step, we set up a transient expression system for leaf protoplasts of Petunia hybrida and used as a model system the inhibition of β-glucuronidase (uidA) expression by uidA antisense gene segments. Both GUS enzyme activities and uidA RNA levels were measured. Co-introducing equal amounts of a full-length uidA antisense gene and a uidA sense gene reduced GUS activity by 60–70%. Various uidA antisense fragments also inhibited expression although with different efficiencies and we show that strong antisense fragments can be retrieved from weak antisense gene fragments. A promoter-less antisense gene did not reduce uidA expression indicating that the inhibition is mediated by antisense transcripts. Using quantitative PCR on first-strand cDNA we show that expression of functional antisense genes lead to reduced levels of uidA mRNA. This suggests that the mechanism of antisense RNA inhibition in protoplasts is similar to that in transgenic plants and that the protoplast system in combination with PCR can be used to preselect antisense fragments of any gene.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Plant molecular biology 13 (1989), S. 287-294 
    ISSN: 1573-5028
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 4
    ISSN: 1573-5028
    Keywords: double promoter ; β-glucuronidase ; cell type specificity ; gene regulation ; seed storage protein gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The activity, tissue specificity and temporal expression of the tandem promoter region preceding a maize zein gene (zE19, encoding a 19 kDa zein protein) were tested in transgenic Petunia plants. To simplify the analysis, the tandem promoter as well as each of the two separate promoter regions were fused to the β-glucuronidase (GUS) reporter gene. All of the three constructs directed the synthesis of GUS in the endosperm of transformed seeds indicating that both separate promoters are independently activated and show the same tissue and cell type specificity observed for zein genes in maize. The kinetics of accumulation and the localization of GUS activity are not coordinated with those of Petunia endogenous seed storage proteins during the development of transformed seeds. Unexpectedly, we detected high levels of GUS activity in anthers of transformed Petunia plants for all three constructs. This appears to reflect the expression pattern of zein genes in maize, since we detect zein transcripts in anthers. Finally, we discuss the possible origin and function of the tandem promoter arrangement on the basis of these data.
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  • 5
    ISSN: 1573-5028
    Keywords: chalcone synthase gene (A) ; flower-specific transient expression ; Petunia hybrida ; promoter analysis ; TACPyAT sequence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In order to scan the 5′ flanking region of the chalcone synthase (chs A) gene for regulatory sequences involved in directing flower-specific and UV-inducible expression, a chimaeric gene was constructed containing the chs A promoter of Petunia hybrida (V30), the chloramphenicol acetyl transferase (cat) structural sequence as a reporter gene and the chs A terminator region of Petunia hybrida (V30). This chimaeric gene and 5′ end deletions thereof were introduced into Petunia plants with the help of Ti plasmid-derived plant vectors and CAT activity was measured. A 220 bp chs A promoter fragment contains cis-acting elements conferring flower-specific and UV-inducible expression. A promoter fragment from −67 to +1, although at a low level, was still able to direct flower-specific expression but could not drive UV-inducible expression in transgenic Petunia seedlings. Molecular analysis of binding of flower nuclear proteins to chs A promoter fragments by gel retardation assays showed strong specific binding to the sequences from −142 to +81. Promoter sequence comparison of chs genes from other plant species, combined with the deletion analysis and gel retardation assays, strongly suggests the involvement of the TACPyAT repeats (−59 and −52) in the regulation of organ-specificity of the chs A gene in Petunia hybrida. We also describe an in vitro organ-specific transient expression system, in which flower or purple callus protoplasts are used, that enables us to pre-screen organ-specific expression of a chimaeric reporter gene.
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  • 6
    ISSN: 1573-5028
    Keywords: alternative promoters ; anther box ; chalcone flavanone isomerase genes ; flower development ; Petunia hybrida
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In this paper we report on the organization and expression of the two chalcone flavanone isomerase (CHI) genes A and B from thePetunia hybrida inbred line V30. From a combination of sequence data, primer extension and RNAse protection experiments we infer the presence of two promoters PA1 and PA2 upstream of the CHI gene A coding region. It is shown that both promoters are used differentially in various flower tissues: the PA1 promoter is active in corolla and tube tissue whereas the PA2 promoter, which gives rise to a 437 bp longer transcript, is only active in late stages of anther development and more specifically in pollen grains. The CHI-B gene, on the other hand, has only one promoter (PB) which is active only in immature anther tissue. Thus, in addition to the use of two alternative promoters in front of the same CHI coding region (CHI-A), the promoters in front of the two distinct CHI gene copies are also used differentially as a mechanism to regulate their expression. Comparison of PB with other flavonoid gene promoters active in immature anther tissue revealed a highly conserved region which was designated as ‘anther box’. We hypothesize that it plays a regulatory role in anther-specific gene expression. Finally, a model describing the evolutionary relationship between both CHI genes is presented.
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  • 7
    ISSN: 1573-5028
    Keywords: antisense RNA ; chalcone synthase (CHS) gene ; Petunia hybrida
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Introduction of a constitutive antisense full-length chalcone synthase (CHS) cDNA gene in petunia can result in an inhibition of flower pigmentation. We have evaluated some of the factors which may be important for the effectiveness of an antisense CHS gene. Antisense CHS genes encoding half-length or quarter-length RNA complementary to the 3′ half of CHS mRNA are able to affect flower pigmentation, while a gene encoding RNA complementary to the 5′ half of CHS mRNA did not show phenotypic effects in transgenic petunia plants. We demonstrate that the RNA encoded by the latter gene has a much lower average steady-state level in leaf tissue than the RNAs encoded by the other antisense gene constructs. We have compared the CaMV 35S and endogenous CHS promoter strengths and intrinsic stabilities of sense and antisense CHS RNAs. From the data we conclude that the constitutive antisense CHS genes are not likely to provide an excess of antisense RNA compared to the CHS mRNA derived from the endogenous genes. Effective inhibition of flower pigmentation is also observed when the antisense CHS gene is under control of the homologous CHS promoter. The results indicate that the mechanism of antisense inhibition cannot solely operate via RNA duplex formation between sense and antisense RNA.
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  • 8
    ISSN: 1573-5028
    Keywords: chalcone synthase genes ; co-ordinate expression ; light regulation ; multigene family ; Petunia hybrida
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have analysed the expression of the 8–10 members of the gene family encoding the flavonoid biosynthetic enzyme chalcone synthase (CHS) from Petunia hybrida. During normal plant development only two members of the gene family (CHS-A and CHS-J) are expressed. Their expression is restricted to floral tissues mainly. About 90% of the total CHS mRNA pool is transcribed from CHS-A, wheares CHS-J delivers about 10% in flower corolla, tube and anthers. Expression of CHS-A and CHS-J during flower development is coordinated and (red) light-dependent. In young seedlings and cell suspension cultures expression of CHS-A and CHS-J can be induced with UV light. In addition to CHS-A and CHS-J, expression of another two CHS genes (CHS-B and CHS-G) is induced in young seedlings by UV light, albeit at a low level. In contrast to CHS genes from Leguminoseae, Petunia CHS genes are not inducible by phytopathogen-derived elicitors. Expression of CHS-A and CHS-J is reduced to a similar extent in a regulatory CHS mutant, Petunia hybrida Red Star, suggesting that both genes are regulated by the same trans-acting factors. Comparison of the promoter sequences of CHS-A and CHS-J reveals some striking homologies, which might represent cis-acting regulatory sequences.
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  • 9
    ISSN: 1573-5028
    Keywords: Petunia hybrida ; anthocyanin ; flower pigmentation ; flavonoid pathway ; A2 ; candi
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The synthesis of anthocyanins in higher plants involves many enzymatic steps. Here we describe the isolation and characterization of a cDNA, ant17, which encodes a protein that has 73% amino acid sequence identity with the candi gene product of Antirrhinum majus and 48% with that of the maize a2 gene. This protein may therefore be involved in the synthesis of anthocyanins in the steps after the action of dihydroflavonol 4-reductase. This is consistent with the absence of ant17 expression in the regulatory anthocyanin mutants of petunia an1, an2 and an11. Furthermore, ant17 is predominantly expressed in corollas and anthers and is induced by gibberellic acid.
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  • 10
    ISSN: 1617-4623
    Keywords: Flavonoids ; Antisense genes ; Chalcone synthase ; Chalcone flavanone isomerase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The constitutive expression of an antisense chalcone synthase (CHS) gene in transgenic petunia plants results with high frequency in a reduced flower pigmentation due to a reduction in the CHS mRNA steady-state level in floral tissue. Here we show that this reduction is specific for CHS mRNA; chalcone flavanone isomerase (CHI) and dihydroflavonol reductase (DFR) mRNA steady-state levels are unaffected. However, in white floral tissue a severe reduction in CHI specific activity is found, accompanied by an altered signal for CHI protein on western blots. We find no correlation between the phenotypic effect of the antisense CHS gene and its chromosomal position. For some of the antisense CHS transformants the flower phenotype is highly variable. We demonstrate that pigmentation in these plants can be influenced by gibberellic acid and light, suggesting that the variable flower phenotype is caused by changes in physiological conditions during flower development. The results not only indicate that flower pigmentation in these plants reveals the variable expression of the antisense transgene, but also show that genomic sequences flanking the transgene may render its expression extremely susceptible to physiological conditions.
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