Loverine Taylor - Academia.edu (original) (raw)
Papers by Loverine Taylor
Annual Review of Plant Physiology and Plant Molecular Biology, Jul 1, 1997
Phytochemistry, Feb 1, 1995
Flavonols are essential for pollen germination and sustained tube growth in Petunia hybrida. An i... more Flavonols are essential for pollen germination and sustained tube growth in Petunia hybrida. An in vitro bioassay, based on biochemical complementation of flavonol-deficient pollen, was used to compare how modifications at different sites on the basic flavonol molecule affect the efficiency of pollen germination. This structural-activity analysis using methylated or glycosylated derivatives showed that only flavonols with unsubstituted hydroxyl groups at positions 3 and 7 could induce rapid pollen germination. In addition, the enhanced germination frequency associated with a hydroxyl group at position 5 was abolished by substituting a methyl group. Increased hydroxylation of the flavonol Bring had an inhibitory effect on germination, but methylation of the same hydroxyl groups promoted germination. Additional hydroxyl groups within the A-ring at carbon 6 had a mixed effect, but a methoxyl group at position 6 enhanced germination in all cases. Substitutions at position 8 were somewhat inhibitory and introduction of an isoprenyl group into ring A was toxic to both mutant and wild type pollen.
Hortscience, May 1, 1994
The Abstracts that follow are arranged in numerical sequence by the abstract number. For Poster S... more The Abstracts that follow are arranged in numerical sequence by the abstract number. For Poster Sessions, the number preceded by PB (i.e., PB XXX) indicates the poster board number on which the poster will be mounted. A participatory, on-farm research project was initiated in 1992 in an effort to enhance mutual learning, knowledge, and experience of integrating cover crops into western Oregon vegetable production systems. A major goal of the project was to include growers, agribusiness representatives, governmental agency, Extension and university researchers in a collaborative learning process, emphasizing grower participation in the design and implementation of on-farm research and demonstration projects. To facilitate this participation from the planning stage forward, four "focus sessions" were hosted by lead farmers in different areas of the Willamette Valley to define growers' needs and interests relating to on-farm research and demonstration trials.
The EMBO Journal
Insertion of the maize transposable element Mu-i into the first intron of the alcohol dehydrogena... more Insertion of the maize transposable element Mu-i into the first intron of the alcohol dehydrogenase locus (Adhl) of maize produced mutant Adhil-S3034 with 40% of the wild-type level of protein and mRNA. Continued instability at this locus resulted in secondary mutations with lower levels of protein expression. One of these, Adhl-S3034a, has no detectable ADH1 expression. This paper describes the precise nature of the changes in the Adhl gene that gave rise to the S3034a allele. The Mu-i element is still present in the mutant, but Adhl sequences immediately adjacent to the element are deleted. The deletion starts precisely at the Mu-i insertion site and extends 74 bp leftward removing part of the first intron, the intron:exon junction and 2 bp of the eleventh amino acid codon in the first exon of the gene. Tests for reversion within the somatic tissue of plants show that mutant S3034a, unlike its progenitor, is stably null for ADH1 activity.
Genetics
We have cloned and sequenced a 1.7-kb M u element from a Mutator line of maize and compared its s... more We have cloned and sequenced a 1.7-kb M u element from a Mutator line of maize and compared its structure to M u l , a 1.4-kb element. With the exception of a 385-bp block of DNA present in the 1.7-kb element, these transposable elements are structurally similar, sharing terminally inverted and internal direct repeated sequences. Derivation of 1.4-kb elements from the 1.7-kb class via deletion of internal sequence is suggested by the finding that a portion of the extra DNA in Mu1.7 is part of a truncated direct repeat sequence in the 1.4-kb element. An abundant poly(A)+ RNA homologous to a portion of this extra DNA is present in several tissues of both Mutator and non-Mutator lines. Analysis of transcripts from an unstable mutant bronzel ( b r ) allele containing a M u l . 7 element inserted in an exon of the gene detects three species of poly(A)+ RNA that hybridize to a Bzl (Bronze) gene probe: the largest contains the entire Mu1.7 element in the Brl gene transcript; another appears to be a spliced, chimeric transcript; the smallest is normal size Bzl mRNA. The latter is most likely encoded by the normal-size alleles detected by Southern analysis of tissue expressing purple pigment, suggesting that normal gene function is restored by excision of the M u l . 7 element.
Wild-type petunia pollen accumulates high levels of flavonol 3-Oglycosides. Pollen from condition... more Wild-type petunia pollen accumulates high levels of flavonol 3-Oglycosides. Pollen from conditionally male-fertile petunia has no flavonols and is unable to germinate. Pollen function is restored both in vivo and in vitro by providing flavonol aglycones, but not flavonol glycosides, to the pollen. In the present study, incubation of an in vitro suspension of conditionally male-fertile pollen with kaempferol or
The Journal of biological chemistry, Jan 26, 1999
Flavonols are plant-specific molecules that are required for pollen germination in maize and petu... more Flavonols are plant-specific molecules that are required for pollen germination in maize and petunia. They exist in planta as both the aglycone and glycosyl conjugates. We identified a flavonol 3-O-galactosyltransferase (F3GalTase) that is expressed exclusively in the male gametophyte and controls the formation of a pollen-specific class of glycosylated flavonols. Thus an essential step to understanding flavonol-induced germination is the characterization of F3GalTase. Amino acid sequences of three peptide fragments of F3GalTase purified from petunia pollen were used to isolate a full-length cDNA clone. RNA gel blot analysis and enzyme assays confirmed that F3GalTase expression is restricted to pollen. Heterologous expression of the F3GalTase cDNA in Escherichia coli yielded active recombinant enzyme (rF3GalTase) which had the identical substrate specificity as the native enzyme. Unlike the relatively nonspecific substrate usage of flavonoid glycosyltransferases from sporophytic tis...
Genetics, 1987
We have cloned and sequenced a 1.7-kb Mu element from a Mutator line of maize and compared its st... more We have cloned and sequenced a 1.7-kb Mu element from a Mutator line of maize and compared its structure to Mu1, a 1.4-kb element. With the exception of a 385-bp block of DNA present in the 1.7-kb element, these transposable elements are structurally similar, sharing terminally inverted and internal direct repeated sequences. Derivation of 1.4-kb elements from the 1.7-kb class via deletion of internal sequence is suggested by the finding that a portion of the extra DNA in Mu1.7 is part of a truncated direct repeat sequence in the 1.4-kb element. An abundant poly(A)+ RNA homologous to a portion of this extra DNA is present in several tissues of both Mutator and non-Mutator lines. Analysis of transcripts from an unstable mutant bronze 1 (bz) allele containing a Mu1.7 element inserted in an exon of the gene detects three species of poly(A)+ RNA that hybridize to a Bz1 (Bronze) gene probe: the largest contains the entire Mu1.7 element in the Bz1 gene transcript; another appears to be a ...
Advances in Experimental Medicine and Biology, 1998
Flavonols are small (C15) plant-specific molecules that are required for petunia and maize pollen... more Flavonols are small (C15) plant-specific molecules that are required for petunia and maize pollen to germinate. They exist in two chemical forms: the aglycone or glycosyl conjugates. Flavonol-deficient pollen is biochemically complemented by flavonol aglycones but not by the glycosylated forms that accumulate in wild type (WT) pollen. Coincident with the biochemical induction of germination, the added flavonol aglycone is rapidly converted to a galactoside and then to a glucosyl galactoside (diglycoside) that is identical to the compound present in WT pollen. A flavonol 3-O-galactosyltransferase (F3GalTase) activity has been identified that controls the formation of glycosylated flavonols in pollen. Importantly, this enzyme also catalyzes the reverse reaction, i.e. the production of the flavonol aglycone from the galactoside and UDP (Fig. 1). F3GalTase/RevGalTase therefore has the potential to control the level of the bioactive flavonol species and as a result, pollen germination.
Flavonol aglycones are required for pollen germination in pe- tunia (Petunia hybrida 1.). Mutant ... more Flavonol aglycones are required for pollen germination in pe- tunia (Petunia hybrida 1.). Mutant plants lacking chalcone synthase (CHS), which catalyzes the first committed step in flavonoid syn- thesis, do not accumulate flavonols and are self-sterile. lhe mutant pollen can be induced to germinate by supplementing it with kaempferol, a flavonol aglycone, either at the time of pollination or by
Methods in Enzymology, 1987
ABSTRACT
The Plant Journal, 1995
Flavanone 3-hydroxylase (F3H) activity is necessary for the production of both flavonols and anth... more Flavanone 3-hydroxylase (F3H) activity is necessary for the production of both flavonols and anthocyanins. Flavonols are required for functional pollen in maize whereas anthocyanins are non-essential pigments. A cDNA for F3H was isolated from Zea mays using a heterologous sequence from Antirrhinum majus. Comparison of the deduced amino acid sequence of maize F3H with other F3H sequences confirmed that the protein is highly conserved among widely divergent plant species. The F3H gene is present in a single copy located at the tip of chromosome 2S. High levels of F3H gene expression were detected in pigmented husk and 26-day postpollination kernels; lower levels in 18-day postpollination kernels and in coleoptiles of germinating seedlings. Slot blot analysis showed that F3H transcript levels in young seedlings are increased by high fluence-rate white light treatment in the presence of the anthocyanin regulatory gene -r. HPLC analysis of extracts from developmentally staged anthers showed that flavonol accumulation begins at the uninucleate microspore stage, continues until maturity, and is not controlled by -r. When the expression pattern of several flavonoid biosynthetic genes was analyzed during microsporogenesis, only F3H transcript accumulation was coordinate with the appearance of flavonols in anthers.
THE PLANT CELL ONLINE, 1990
The flavonoid pathway leading to anthocyanin biosynthesis in maize is controlled by multiple regu... more The flavonoid pathway leading to anthocyanin biosynthesis in maize is controlled by multiple regulatory genes and induced by various developmental and environmental factors. We have investigated the effect of the regulatory loci R, B, and f / on anthocyanin accumulation and on the expression of four genes ( C2, A l , 621, and 822) in the biosynthetic pathway during an inductive light treatment. The results show that light-mediated anthocyanin biosynthesis is regulated solely by R; the contributions of B and f / are negligible in young seedlings. lnduction of the A1 and Bz2 genes by high fluence-rate white light requires the expression of a dominant R allele, whereas accumulation of C2 and Bzl mRNA occurs with either a dominant or recessive allele at R. A1 and 822 mRNA accumulate only in response to high fluence-rate white light, but Bzl is fully expressed in dim red light. Some C2 mRNA is induced by dim red light, but accumulation is far greater in high fluence-rate white light. Furthe'more, expression from both dominant and recessive alleles of the regulatory gene R is enhanced by high fluence-rate white light. Seedlings with a recessive allele at R produce functional chalcone synthase protein (the C2 gene product) but accumulate no anthocyanins, suggesting that, in contrast to the R-mediated coordinate regulation of C2 and Bzl observed in the aleurone, C2 expression in seedlings is independent of R and appears to be regulated by a different light-sensitive pathway.
THE PLANT CELL ONLINE, 1994
Flavonols are essential for pollen germination and tube growth in petunia and can be supplled by ... more Flavonols are essential for pollen germination and tube growth in petunia and can be supplled by either the pollen or stigma at pollinatlon. HPLC analysis and a sensitive bloassay demonstrated that both pollinatlon and wounding induce flavonol accumulation, especlally kaempferol, in the outer cell layers and exudate of the stigma. Pollination and wounding induced nearly identical flavonol kinetics and patterns of accumulation in the same target tissue, suggesting that they sham elements of a common signal transductlon pathway. The wound response was systemlc, because kaempferol accumulated in the stlgma when dista1 tissues, such as the corolla, stamens, or sepals, were wounded. We have exploited the germination requirement for flavonols and the high leve1 of kaempferol that accumulates after wounding to enhance plant fecundity. Seed set was slgnificantly increased by mechanically wounding the corolla and stamens prior to the application of pollen to the stigma. A reproductive role for a plant secondary metabolite and the specific function of stigmatic kaempferol are discussed from an evolutionary perspective.
Sexual Plant Reproduction, 1995
This study compares conditional male fertility (CMF) in maize and petunia. CMF is a reversible de... more This study compares conditional male fertility (CMF) in maize and petunia. CMF is a reversible defect in pollen germination or tube growth; pollen is nonfunctional in self-crosses but fully functional in outcrosses or when supplied with specific flavonol aglycones at pollination. CMF occurs in maize and petunia mutants that lack chalcone synthase (CHS) activity and therefore do not synthesize flavonols. In maize CMF seedlings and developing male florets, CHS transcripts accumulate to high levels, yet western blot analysis using an anti-CHS antiserum does not detect any CHS protein. This is in contrast to CMF petunia, where no CHS RNA is detected . While CMF petunia pollen requires flavonols to germinate, CMF maize pollen germinates and grows both in vivo and in vitro without the addition of flavonols. However, pollen tubes abort after 12 h of growth which explains the lack of seed set in self crosses . Pollen tubes of CMF maize have an unusual morphology in vivo, with heavy callose deposits throughout the tube and tips that burst within the silk. Normal tube morphology and seed set are restored by adding flavonols to the silks at pollination. As previously shown with petunia, fecundity (seed set) may be enhanced in maize by adding quercetin and kaempferol at pollination.
Proceedings of the National Academy of Sciences, 1992
Chalcone synthase catalyzes the initial step of that branch of the phenylpropanoid pathway that l... more Chalcone synthase catalyzes the initial step of that branch of the phenylpropanoid pathway that leads to flavonoids. A lack of chalcone synthase activity has a pleiotropic effect in maize and petunia mutants: pollen fertility as well
Annual Review of Plant Physiology and Plant Molecular Biology, Jul 1, 1997
Phytochemistry, Feb 1, 1995
Flavonols are essential for pollen germination and sustained tube growth in Petunia hybrida. An i... more Flavonols are essential for pollen germination and sustained tube growth in Petunia hybrida. An in vitro bioassay, based on biochemical complementation of flavonol-deficient pollen, was used to compare how modifications at different sites on the basic flavonol molecule affect the efficiency of pollen germination. This structural-activity analysis using methylated or glycosylated derivatives showed that only flavonols with unsubstituted hydroxyl groups at positions 3 and 7 could induce rapid pollen germination. In addition, the enhanced germination frequency associated with a hydroxyl group at position 5 was abolished by substituting a methyl group. Increased hydroxylation of the flavonol Bring had an inhibitory effect on germination, but methylation of the same hydroxyl groups promoted germination. Additional hydroxyl groups within the A-ring at carbon 6 had a mixed effect, but a methoxyl group at position 6 enhanced germination in all cases. Substitutions at position 8 were somewhat inhibitory and introduction of an isoprenyl group into ring A was toxic to both mutant and wild type pollen.
Hortscience, May 1, 1994
The Abstracts that follow are arranged in numerical sequence by the abstract number. For Poster S... more The Abstracts that follow are arranged in numerical sequence by the abstract number. For Poster Sessions, the number preceded by PB (i.e., PB XXX) indicates the poster board number on which the poster will be mounted. A participatory, on-farm research project was initiated in 1992 in an effort to enhance mutual learning, knowledge, and experience of integrating cover crops into western Oregon vegetable production systems. A major goal of the project was to include growers, agribusiness representatives, governmental agency, Extension and university researchers in a collaborative learning process, emphasizing grower participation in the design and implementation of on-farm research and demonstration projects. To facilitate this participation from the planning stage forward, four "focus sessions" were hosted by lead farmers in different areas of the Willamette Valley to define growers' needs and interests relating to on-farm research and demonstration trials.
The EMBO Journal
Insertion of the maize transposable element Mu-i into the first intron of the alcohol dehydrogena... more Insertion of the maize transposable element Mu-i into the first intron of the alcohol dehydrogenase locus (Adhl) of maize produced mutant Adhil-S3034 with 40% of the wild-type level of protein and mRNA. Continued instability at this locus resulted in secondary mutations with lower levels of protein expression. One of these, Adhl-S3034a, has no detectable ADH1 expression. This paper describes the precise nature of the changes in the Adhl gene that gave rise to the S3034a allele. The Mu-i element is still present in the mutant, but Adhl sequences immediately adjacent to the element are deleted. The deletion starts precisely at the Mu-i insertion site and extends 74 bp leftward removing part of the first intron, the intron:exon junction and 2 bp of the eleventh amino acid codon in the first exon of the gene. Tests for reversion within the somatic tissue of plants show that mutant S3034a, unlike its progenitor, is stably null for ADH1 activity.
Genetics
We have cloned and sequenced a 1.7-kb M u element from a Mutator line of maize and compared its s... more We have cloned and sequenced a 1.7-kb M u element from a Mutator line of maize and compared its structure to M u l , a 1.4-kb element. With the exception of a 385-bp block of DNA present in the 1.7-kb element, these transposable elements are structurally similar, sharing terminally inverted and internal direct repeated sequences. Derivation of 1.4-kb elements from the 1.7-kb class via deletion of internal sequence is suggested by the finding that a portion of the extra DNA in Mu1.7 is part of a truncated direct repeat sequence in the 1.4-kb element. An abundant poly(A)+ RNA homologous to a portion of this extra DNA is present in several tissues of both Mutator and non-Mutator lines. Analysis of transcripts from an unstable mutant bronzel ( b r ) allele containing a M u l . 7 element inserted in an exon of the gene detects three species of poly(A)+ RNA that hybridize to a Bzl (Bronze) gene probe: the largest contains the entire Mu1.7 element in the Brl gene transcript; another appears to be a spliced, chimeric transcript; the smallest is normal size Bzl mRNA. The latter is most likely encoded by the normal-size alleles detected by Southern analysis of tissue expressing purple pigment, suggesting that normal gene function is restored by excision of the M u l . 7 element.
Wild-type petunia pollen accumulates high levels of flavonol 3-Oglycosides. Pollen from condition... more Wild-type petunia pollen accumulates high levels of flavonol 3-Oglycosides. Pollen from conditionally male-fertile petunia has no flavonols and is unable to germinate. Pollen function is restored both in vivo and in vitro by providing flavonol aglycones, but not flavonol glycosides, to the pollen. In the present study, incubation of an in vitro suspension of conditionally male-fertile pollen with kaempferol or
The Journal of biological chemistry, Jan 26, 1999
Flavonols are plant-specific molecules that are required for pollen germination in maize and petu... more Flavonols are plant-specific molecules that are required for pollen germination in maize and petunia. They exist in planta as both the aglycone and glycosyl conjugates. We identified a flavonol 3-O-galactosyltransferase (F3GalTase) that is expressed exclusively in the male gametophyte and controls the formation of a pollen-specific class of glycosylated flavonols. Thus an essential step to understanding flavonol-induced germination is the characterization of F3GalTase. Amino acid sequences of three peptide fragments of F3GalTase purified from petunia pollen were used to isolate a full-length cDNA clone. RNA gel blot analysis and enzyme assays confirmed that F3GalTase expression is restricted to pollen. Heterologous expression of the F3GalTase cDNA in Escherichia coli yielded active recombinant enzyme (rF3GalTase) which had the identical substrate specificity as the native enzyme. Unlike the relatively nonspecific substrate usage of flavonoid glycosyltransferases from sporophytic tis...
Genetics, 1987
We have cloned and sequenced a 1.7-kb Mu element from a Mutator line of maize and compared its st... more We have cloned and sequenced a 1.7-kb Mu element from a Mutator line of maize and compared its structure to Mu1, a 1.4-kb element. With the exception of a 385-bp block of DNA present in the 1.7-kb element, these transposable elements are structurally similar, sharing terminally inverted and internal direct repeated sequences. Derivation of 1.4-kb elements from the 1.7-kb class via deletion of internal sequence is suggested by the finding that a portion of the extra DNA in Mu1.7 is part of a truncated direct repeat sequence in the 1.4-kb element. An abundant poly(A)+ RNA homologous to a portion of this extra DNA is present in several tissues of both Mutator and non-Mutator lines. Analysis of transcripts from an unstable mutant bronze 1 (bz) allele containing a Mu1.7 element inserted in an exon of the gene detects three species of poly(A)+ RNA that hybridize to a Bz1 (Bronze) gene probe: the largest contains the entire Mu1.7 element in the Bz1 gene transcript; another appears to be a ...
Advances in Experimental Medicine and Biology, 1998
Flavonols are small (C15) plant-specific molecules that are required for petunia and maize pollen... more Flavonols are small (C15) plant-specific molecules that are required for petunia and maize pollen to germinate. They exist in two chemical forms: the aglycone or glycosyl conjugates. Flavonol-deficient pollen is biochemically complemented by flavonol aglycones but not by the glycosylated forms that accumulate in wild type (WT) pollen. Coincident with the biochemical induction of germination, the added flavonol aglycone is rapidly converted to a galactoside and then to a glucosyl galactoside (diglycoside) that is identical to the compound present in WT pollen. A flavonol 3-O-galactosyltransferase (F3GalTase) activity has been identified that controls the formation of glycosylated flavonols in pollen. Importantly, this enzyme also catalyzes the reverse reaction, i.e. the production of the flavonol aglycone from the galactoside and UDP (Fig. 1). F3GalTase/RevGalTase therefore has the potential to control the level of the bioactive flavonol species and as a result, pollen germination.
Flavonol aglycones are required for pollen germination in pe- tunia (Petunia hybrida 1.). Mutant ... more Flavonol aglycones are required for pollen germination in pe- tunia (Petunia hybrida 1.). Mutant plants lacking chalcone synthase (CHS), which catalyzes the first committed step in flavonoid syn- thesis, do not accumulate flavonols and are self-sterile. lhe mutant pollen can be induced to germinate by supplementing it with kaempferol, a flavonol aglycone, either at the time of pollination or by
Methods in Enzymology, 1987
ABSTRACT
The Plant Journal, 1995
Flavanone 3-hydroxylase (F3H) activity is necessary for the production of both flavonols and anth... more Flavanone 3-hydroxylase (F3H) activity is necessary for the production of both flavonols and anthocyanins. Flavonols are required for functional pollen in maize whereas anthocyanins are non-essential pigments. A cDNA for F3H was isolated from Zea mays using a heterologous sequence from Antirrhinum majus. Comparison of the deduced amino acid sequence of maize F3H with other F3H sequences confirmed that the protein is highly conserved among widely divergent plant species. The F3H gene is present in a single copy located at the tip of chromosome 2S. High levels of F3H gene expression were detected in pigmented husk and 26-day postpollination kernels; lower levels in 18-day postpollination kernels and in coleoptiles of germinating seedlings. Slot blot analysis showed that F3H transcript levels in young seedlings are increased by high fluence-rate white light treatment in the presence of the anthocyanin regulatory gene -r. HPLC analysis of extracts from developmentally staged anthers showed that flavonol accumulation begins at the uninucleate microspore stage, continues until maturity, and is not controlled by -r. When the expression pattern of several flavonoid biosynthetic genes was analyzed during microsporogenesis, only F3H transcript accumulation was coordinate with the appearance of flavonols in anthers.
THE PLANT CELL ONLINE, 1990
The flavonoid pathway leading to anthocyanin biosynthesis in maize is controlled by multiple regu... more The flavonoid pathway leading to anthocyanin biosynthesis in maize is controlled by multiple regulatory genes and induced by various developmental and environmental factors. We have investigated the effect of the regulatory loci R, B, and f / on anthocyanin accumulation and on the expression of four genes ( C2, A l , 621, and 822) in the biosynthetic pathway during an inductive light treatment. The results show that light-mediated anthocyanin biosynthesis is regulated solely by R; the contributions of B and f / are negligible in young seedlings. lnduction of the A1 and Bz2 genes by high fluence-rate white light requires the expression of a dominant R allele, whereas accumulation of C2 and Bzl mRNA occurs with either a dominant or recessive allele at R. A1 and 822 mRNA accumulate only in response to high fluence-rate white light, but Bzl is fully expressed in dim red light. Some C2 mRNA is induced by dim red light, but accumulation is far greater in high fluence-rate white light. Furthe'more, expression from both dominant and recessive alleles of the regulatory gene R is enhanced by high fluence-rate white light. Seedlings with a recessive allele at R produce functional chalcone synthase protein (the C2 gene product) but accumulate no anthocyanins, suggesting that, in contrast to the R-mediated coordinate regulation of C2 and Bzl observed in the aleurone, C2 expression in seedlings is independent of R and appears to be regulated by a different light-sensitive pathway.
THE PLANT CELL ONLINE, 1994
Flavonols are essential for pollen germination and tube growth in petunia and can be supplled by ... more Flavonols are essential for pollen germination and tube growth in petunia and can be supplled by either the pollen or stigma at pollinatlon. HPLC analysis and a sensitive bloassay demonstrated that both pollinatlon and wounding induce flavonol accumulation, especlally kaempferol, in the outer cell layers and exudate of the stigma. Pollination and wounding induced nearly identical flavonol kinetics and patterns of accumulation in the same target tissue, suggesting that they sham elements of a common signal transductlon pathway. The wound response was systemlc, because kaempferol accumulated in the stlgma when dista1 tissues, such as the corolla, stamens, or sepals, were wounded. We have exploited the germination requirement for flavonols and the high leve1 of kaempferol that accumulates after wounding to enhance plant fecundity. Seed set was slgnificantly increased by mechanically wounding the corolla and stamens prior to the application of pollen to the stigma. A reproductive role for a plant secondary metabolite and the specific function of stigmatic kaempferol are discussed from an evolutionary perspective.
Sexual Plant Reproduction, 1995
This study compares conditional male fertility (CMF) in maize and petunia. CMF is a reversible de... more This study compares conditional male fertility (CMF) in maize and petunia. CMF is a reversible defect in pollen germination or tube growth; pollen is nonfunctional in self-crosses but fully functional in outcrosses or when supplied with specific flavonol aglycones at pollination. CMF occurs in maize and petunia mutants that lack chalcone synthase (CHS) activity and therefore do not synthesize flavonols. In maize CMF seedlings and developing male florets, CHS transcripts accumulate to high levels, yet western blot analysis using an anti-CHS antiserum does not detect any CHS protein. This is in contrast to CMF petunia, where no CHS RNA is detected . While CMF petunia pollen requires flavonols to germinate, CMF maize pollen germinates and grows both in vivo and in vitro without the addition of flavonols. However, pollen tubes abort after 12 h of growth which explains the lack of seed set in self crosses . Pollen tubes of CMF maize have an unusual morphology in vivo, with heavy callose deposits throughout the tube and tips that burst within the silk. Normal tube morphology and seed set are restored by adding flavonols to the silks at pollination. As previously shown with petunia, fecundity (seed set) may be enhanced in maize by adding quercetin and kaempferol at pollination.
Proceedings of the National Academy of Sciences, 1992
Chalcone synthase catalyzes the initial step of that branch of the phenylpropanoid pathway that l... more Chalcone synthase catalyzes the initial step of that branch of the phenylpropanoid pathway that leads to flavonoids. A lack of chalcone synthase activity has a pleiotropic effect in maize and petunia mutants: pollen fertility as well