Progress 10/01/07 to 09/30/08
Outputs
OUTPUTS: One graduate student and three undergraduate students were involved in this research. Talks or posters describing this research were given at a Gordon Conference, a FASEB conference and an ASPB conference. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Plant geneticists interested in hypervaecumulation of metals such as arsenic. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
We have identified and characterized a gene from the fern Pteris vittata that has hallmarks of an arsenite pump. This is important as it may be necessary and sufficient for this plant to tolerate and hyperaccumulate arsenic. We have shown that knocking-down the expression of this gene does affect the growth of plants on arsenic, indicating that this gene is necessary for arsenic tolerance in this unusual plant.
Publications
- Chan AP, Melake-Berhan A, O'Brien K, Buckley S, Quan H, Chen D, Lewis M, Banks JA, Rabinowicz PD. 2008. The highest-copy repeats are methylated in the small genome of the early divergent vascular plant Selaginella moellendorffii. BMC Genomics. 12:282.
- Hirano K, Nakajima M, Asano K, Nishiyama T, Sakakibara H, Kojima M, Katoh E, Xiang H, Tanahashi T, Hasebe M, Banks JA, Ashikari M, Kitano H, Ueguchi-Tanaka M, Matsuoka M. 2007. The GID1-mediated gibberellin perception mechanism is conserved in the Lycophyte Selaginella moellendorffii but not in the Bryophyte Physcomitrella patens. Plant Cell. 19:3058-79.
- Banks JA. 2008. MicroRNA, sex determination and floral meristem determinacy in maize. Genome Biol. 9:204.
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Progress 10/01/03 to 09/30/08
Outputs
OUTPUTS: Termination report filed in 2008 PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
x
Publications
- No publications reported this period
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Progress 10/01/06 to 09/30/07
Outputs
I worked at NSF as the Program Director for the Plant, Microbial and Yeast Developmental Mechanisms Program at NSF.
Impacts
I worked at NSF as the Program Director for the Plant, Microbial and Yeast Developmental Mechanisms Program at NSF.
Publications
- No publications reported this period
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Progress 10/01/05 to 09/30/06
Outputs
Our lab focuses on two research problems. The goal of the first is to understand the genetic and molecular basis of sex determination in plants using the fern Ceratopteris richardii as a model system for study. Our second research goal is to understand how Pteris vittata, another homosporous fern, hyperaccumulates arsenic at extraordinary levels. Determining the structure of Antheridiogen (ACE). ACE from 1200 liters of conditioned medium has been concentrated and purified by normal and reverse phase chromatography, solvent partitioning and HPLC. We have determined the molecular weight of the HPLC purified bioactive fractions using ESI-MS using a FT-ICR-MS on very small quantities of material. These studies show that antheridiogen is a novel gibberellin, a class of common plant growth regulators. Our strategy is to use high throughput gene expression profiling to identify sex-specific genes. To this end a normalized and macroarrayed cDNA library (already constructed)
will be probed with cDNAs generated from male and female gametophytes of varying stages of development. Candidate genes that show statistically significant changes in expression will be tested for function. RNA interference will allow us to determine the functions of these candidate genes and their role in the sex-determining process. Pteris vittata cDNA's that can complement defects in the arsenic tolerance mechanism of carefully selected yeast mutants have been sought. We are now using the gene silencing (RNAi) technique recently developed for fern gametophytes to confirm the role of these genes in arsenic hyperaccumulation in P. vittata. Genes confirmed to play a role in arsenic hyperaccumulation in P. vittata are being overexpressed in the model flowering plant Arabidopsis thaliana to test the utility of the genes for development of arsenic phytoremediation plants. Pteris vittata mutants with altered arsenic hyperaccumulation properties also will be identified by mutagenesis and
screening of spores unable to germinate or develop in the presence of arsenate. Different ecotypes or accessions of P. vittata that vary in their ability to hyperaccumulate arsenic will also be sought through screening of a wide range of field collected specimens. This will allow us to determine the number of genetic loci that are responsible for arsenic hyperaccumulation in P. vittata, and provide the genetic material that will ultimately allow the positional cloning of genes responsible for arsenic hyperaccumulation.
Impacts
We have identified signaling molecules in the fern Ceratopteris richardii that are necessary for male sex determination and differentiation. We have also identified two genes in the fern Pteris vittata that are likely to make it able to hyperaccumulate and tolerate high levels of arsenic, an environmental toxin. Sex determination and reproduction in plants has and will continue to be an important process in agriculture and crop propagation, while the identification of arsenic-related genes will be important in future attempts to remediate arsenic contamination from soils.
Publications
- No publications reported this period
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Progress 10/01/04 to 09/30/05
Outputs
We have identified signaling molecules and genes in the fern Ceratopteris richardii that are necessary for sex determination and differentiation. We have also identified 2 genes in the fern Pteris vittata that make it able to hyperaccumulate and tolerate high levels of arsenic. One is an arsenic reductase and the other encodes a putative protein that is necessary to shuffle arsenic to the vacuole of the cell.
Impacts
Understanding the genetic basis of arsenic hyperaccumulation in this extraordinary fern will be useful for the remediation of arsenic contaminated sites.
Publications
- Wang W, Tanurdzic M, Luo M, Sisneros N, Kim HR, Weng JK, Kudrna D, Mueller C, Arumuganathan K, Carlson J, Chapple C, de Pamphilis C, Mandoli D, Tomkins J, Wing RA, Banks JA. 2005 Construction of a bacterial artificial chromosome library from the spikemoss Selaginella moellendorffii: a new resource for plant comparative genomics. BMC Plant Biol. 5:10-15.
- Sano R, Juarez CM, Hass B, Sakakibara K, Ito M, Banks JA, Hasebe M. 2005. KNOX homeobox genes potentially have similar function in both diploid unicellular and multicellular meristems, but not in haploid meristems. Evol Dev. 7:69-78.
- Gumaelius L, Lahner B, Salt DE, Banks JA. 2004. Arsenic hyperaccumulation in gametophytes of Pteris vittata. A new model system for analysis of arsenic hyperaccumulation. Plant Physiol. 136:3198-208.
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Progress 10/01/03 to 09/29/04
Outputs
We have succeeded in cloning several genes that are involved in specific aspects of plant gametophyte development, as detailed in our project summary. The first gene is one that is necessary for the development of female traits in the gametophyte. When this gene is inactivated in a female, it causes the female to switch to a male program of development. Furthermore, we suspect that this gene is regulated by a mechanism involving microRNAs. If true, this would be the first example of an organism that regulates it sex via this mechanism. We have also cloned two arsenic-related genes from the fern Pteris vittata. One reduces arsenate to arsenite, while the other may be necessary to localize arsenite to the vacuole of the cell where it can do no damage. The latter gene is not found in other crop or flowering plants, proving that the study of ferns and their unique biology are important for discovering new genes and useful biological processes in plants.
Impacts
Identifying the genes involved in arsenic hyperaccumulation in Pteris vittata will allow us to identify plants that could be used to phytoremediate soils contaminated by arsenic. Identifying genes involved in sex determination in plants will enable us to genetically modify the gender of crop plants so that they can be more easily bred and cultivated.
Publications
- Rutherford G, Tanurdzic M, Hasebe M, Banks JA. 2004. A systemic gene silencing method suitable for high throughput, reverse genetic analyses of gene function in fern gametophytes. BMC Plant Biol. 2004: 6-12.
- Tanurdzic M, Banks J. 2004. Sex-determining mechanisms in land plants. Plant Cell. 16: S61-71.
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Progress 10/01/02 to 09/30/03
Outputs
In regards to our goal of identifying the male sex-determining pheromone in the fern Ceratopteris, we have succeeded in narrowing its structure to one of several gibberellins, which are important growth hormones in all plants. We have also successfully demonstrated that a method commonly referred to as RNAi can be used to analyze the functions of genes. Using this method, we have identified one gene that is involved in sex determination in Ceratopteris, as its silencing leads to male gametophytes under conditions that would cause them to develop as females. We have also conducted several physiological studies of arsenic hyperaccumulation in the fern Pteris vittata. These studies indicate that in addition to arsenic hyperaccumulation, this species also hyperaccumulates antimony. We have also begun to screen mutagenized P. vittata spores for enhanced tolerance to arsenic, as well as generate cDNA expression libraries to isolated potential arsenate reductase genes in E.
coli and yeast.
Impacts
Identifying the genes involved in arsenic hyperaccumulation in Pteris vittata will allow us to identify plants that could be used to phytoremediate soils contaminated by arsenic. Identifying genes involved in sex determination in plants will enable us to genetically modify the gender of crop plants so that they can be more easily bred and cultivated.
Publications
- No publications reported this period
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Progress 10/01/00 to 09/30/01
Outputs
Our research is aimed at understanding how the gender of a plant (male or female) is determined. Using a simple fern as a model system, we have genetically identified more than 50 genes that, when disrupted, alter the gender of the individual. During the past year, we have worked toward developing a transformation protocol that ultimately will allow us to clone these genes and provide us with the tools necessary to understand how they function to regulate sex expression in plants. We have also discovered that a steroid hormone, called brassinolide, promotes the development of male traits and represses female traits in the fern. Brassinolides have been found to accumulate in the sperm-containing pollen of many flowering plants, including crop plants. This research will give us important insights into understanding how steroid hormones influence sexual reproduction in all plants.
Impacts
Manipulating sexual reproduction in plants has and will continue to be an important process in agriculture and crop improvement. Our research, which is aimed at understanding how a plant determines whether it is male or female, provides a basic understanding of the genes involved in this process.
Publications
- Strain, Errol, Barbara Hass and Jo Ann Banks. 2001. Characterization of mutations that feminize gametophytes of the fern Ceratopteris. Genetics, 159, (in press).
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Progress 10/01/99 to 09/30/00
Outputs
Our research is aimed at understanding how the gender of a plant (male or female) is determined. Using a simple fern as a model system, we have genetically identified more than 50 genes that, when disrupted, alter the gender of the individual. During the past year, we have worked toward developing a transformation protocol that ultimately will allow us to clone these genes and provide us with the tools necessary to understand how they function to regulate sex expression in plants. We have also discovered that a steroid hormone, called brassinolide, promotes the development of male traits and represses female traits in the fern. Brassinolides have been found to accumulate in the sperm-containing pollen of many flowering plants, including crop plants. This research will give us important insights into understanding how steroid hormones influence sexual reproduction in all plants.
Impacts
Manipulating sexual reproduction in plants has and will continue to be an important process in agriculture and crop improvement. Our research, which is aimed at understanding how a plant determines whether it is male or female, provides a basic understanding of the genes involved in this process.
Publications
- Banks, J. 1999. Gametophyte development in ferns. Ann. Rev. Plant Phys. Plant Mol. Biol. 50:163-186.
- Aso*, K., M. Kato*, J. Banks and M. Hasebe*. 1999. Characterization of homeodomain-leucine zipper genes in the fern Ceratopteris richardii and the evolution of the homeodomain-leucine zipper gene family in vascular plants. Mol. Biol. Evol. 16:544-552.
- Wen*, C., R. Smith and J. Banks*. 1999. ANI1: A sex pheromone-induced gene in Ceratopteris gametophytes and its possible role in sex determination. Plant Cell 11:1307-1317.
- Hass, B., Evers, K., Wen, C., Smith, R., and J. Banks. Analysis of an antheridiogen-induced gene, ANI1, in Ceratopteris richardii. International Botanical Congress Proceedings, St. Louis MO, August 1999.
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Progress 10/01/98 to 09/30/99
Outputs
The objective of our research is to understand how gender is determined in plants using a model plant system, the fern Ceratopteris. We have used a genetic approach to find mutations that affect the sex of the Ceratopteris gametophyte and have characterized several mutations that cause the plant to develop as a female. These mutations define the genes that are necessary for the development of male traits. We have also characterized a gene that is expressed specifically during male development. This gene (ANI1) is a member of the lipocalin family of genes. In animals, lipocalin genes encode proteins that bind steroid hormones, pheromones and odorants. Binding to these receptors sets in motion a series of events that ultimately leads to a behavioral or biochemical response. Experiments to determine the chemical structure of the Ceratopteris sex-determining pheromone and its binding to the ANI1 protein are in progress. We have started to develop a physical map of the
Ceratopteris genome, as well as begun using new genomics approaches to understand sex determination in plants. We have isolated cDNAs of genes that are expressed during the sex-determining period.
Impacts
By determining the sequence of these genes, we hope to identify all genes that are involved in this important developmental process.
Publications
- Banks, J. 1999. Gametophyte development in ferns. Ann. Rev. Plant Phys. Plant Mol. Biol. 50:163-186.
- Aso, K., M. Kato, J. Banks and M. Hasebe. 1999. Characterization of homeodomain-leucine zipper genes in the fern Ceratopteris richardii and the evolution of the homeodomain-leucine zipper gene family in vascular plants. Mol. Biol. Evol. 16:544-552.
- Wen, C., R. Smith and J. Banks. 1999. ANI1: A sex pheromone-induced gene in Ceratopteris gametophytes and its possible role in sex determination. Plant Cell 11:1307-1317.
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Progress 10/01/97 to 09/30/98
Outputs
The objective of our research is to understand how sex is determined in plants using a model plant system, the fern Ceratopteris. We have used a genetic approach to find mutations that affect the sex of the Ceratopteris gametophyte and have isolated several mutations that cause the plant to develop as a female (not male) in 1998. We have also characterized a gene that is expressed specifically during male development. This gene (ANI1) is a member of the lipocalin family of genes. In animals, lipocalin genes encode proteins that bind steroid hormones, pheromones and odorants. Binding to these receptors sets in motion a series of events that ultimately leads to a behavioral or biochemical response. Experiments to determine the chemical structure of the Ceratopteris sex-determining pheromone and its binding to the ANI1 protein are in progress. Another Ceratopteris gene discovered in our lab is homologous to genes of flowering plants that are required for meristem
development. Because a meristem is a female trait of the gametophyte, this gene is likely to be a target of repression by the male-inducing pheromone in Ceratopteris. The function of the Ceratopteris gene has been assessed by over-expressing it in Arabidopsis plants. Such plants are similar to Arabiodpsis plants defective in gibberellin biosynthesis as they are small, have multiple shoots and are delayed in flowering. Future experiments with Ceratopteris will allow us to address how a known signal (the sex pheromone) regulates the expression of this important gene.
Impacts
(N/A)
Publications
- DeYoung, B.*, T. Weber*, B. Hass* and J. Banks*. 1997. Generating tetraploid sporophytes and their use in analyzing mutations affecting gametophyte development in the fern Ceratopteris. Genetics 147:809-814.
- Banks, J.* 1997. The TRANSFORMER genes of the fern Ceratopteris simultaneously promote meristem and archegonia development and repress antheridia development in the developing gametophyte. Genetics 147:1885-1897.
- Banks, J. 1997. Sex determination in the fern Ceratopteris. Trends in Plant Science 2:175-180.
- Juarez, C. and J. Banks. 1997. Sex determination in plants. Current Opin. in Plant Sci 1:68-72.
- Hasebe,* M., C. Wen*, M. Kato* and J. Banks*. 1998. The expression of MADS box homeotic genes in the fern Ceratopteris richardii. Proc. Nat. Acad. Sci. 95:6222-6227.
- Hasebe, M. and J. Banks. 1997. The evolution of MADS box genes in seed plants. Pages 179-197 in: Evolution and Diversification of Land Plants. K. Iwatsuki and P. Raven, eds. Springer-Verlag, Tokyo.
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Progress 10/01/96 to 09/30/97
Outputs
The objective of our research is to understand how sex is determined in plants using a model plant system, the fern Ceratopteris. We have used a genetic approach to isolate mutations that affect the sex of the Ceratopteris gametophyte. Normally, the sex of the gametophyte is either male or hermaphroditic. The determinant of sex type is the pheromone antheridiogen which is secreted by the hermaphrodite and induces male development of immature gametophytes. The mutants we have isolated include the hermaphroditic mutants which cannot respond to the pheromone and are always hermaphroditic; a femininization mutant which cannot produce sperm-forming antheridia; and transformer mutants which is male even in the absence of the male-inducing pheromone. Each of these mutations defines key regulatory genes necessary for appropriate sex expression in this organism. By making double and triple mutant gametophyes for each of these genes, we have shown that these genes interact with
one another in a simple regulatory pathway. Several of the genes that are differentially expressed in male and hermaphrodite development. One gene (called ANI-1) that is induced by the sex pheromone in Ceratopteris is a member of the lipocalin family of genes. In animals, lipocalin genes encode proteins that bind steroid hormones, pheromones and odorants, and then carry them to their appropriate receptors. Binding to these receptors sets in motion a series of events that ultimately leads to a behavioral or biochemical response. Although the ANI-1 gene is the first lipocalin-type gene identified in plants, it is an important component of the sex-determining process in Ceratopteris and is perhaps important in all gibberellin responses in plants. Experiments to determine the chemical structure of the Ceratopteris pheromone are underway, and this work is being determined in collaboration with Dr. Clint Chapple (Department of Biochemistry, Purdue University) and Dr. Lewis Mander
(Department of Chemistry, Australian National University). The protein structure of the lipocalin-like protein is being determined in collaboration with Dr. Michael Rossman (Department of Biology, Purdue University). Another Ceratopteris gene discovered in our lab is homologous to genes of maize and Arabidopsis that are required for meristem development. Because a meristem is a female trait of the gametophyte, this gene is likely to be a target of repression by the male-inducing pheromone in Ceratopteris. The function of the Ceratopteris gene has been assessed by over-expressing it in Arabidopsis plants. Such plants are similar to Arabiodpsis plants defective in gibberellin biosynthesis as they are small, have multiple shoots and are delayed in flowering. Future experiments with Ceratopteris will allow us to address how a known signal (the sex pheromone) regulates the expression of this important gene.
Impacts
(N/A)
Publications
- Wen, C. and J. Banks. 1996. Antheridiogen-induced genes in Ceratopteris. FASEB Research Meeting on Plant Developmental Genetics.
- Juarez, C. and J. Banks. 1996. Cloning a knotted homolog from Ceratopteris. FASEB Research Meeting on Plant Developmental Genetics.
- Eberle, J. and J. Banks. 1996. Genetic interactions among sex-determining genes in the fern Ceratopteris. Genetics 142:973-985.
- Jennings, J., J. Banks and R. Coolbaugh. 1996. Subtractive hybridization between cDNAs from untreated and AMO-1618-treated cultures of Gibberella fujikuroi. Plant Cell Physiol 37:847-854.
- DeYoung, B., T. Weber, B. Hass and J. Banks. 1997. Generating tetraploid sporophytes and their use in analyzing mutations affecting gametophyte development in the fern Ceratopteris. Genetics, 147:809-814.
- Hasebe, M. and J. Banks. 1997. The evolution of MADS box genes in seed plants. Pages 179-197 in: Evolution and Diversification of Land Plants. K. Iwatsuki and P. Raven, eds. Springer-Verlag, Tokyo.
- Banks, J. 1997. Sex determination in the fern Ceratopteris. Trends in Plant Science 2:175-180.
- Juarez, C. and J. Banks. 1997. Sex determination in plants. Current Opin. in Plant Sci. (in press).
- Banks, J. 1997. The TRANSFORMER genes of the fern Ceratopteris simultaneously promote meristem and archegonia development and repress antheridia development in the developing gametophyte. Genetics, in press.
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Progress 10/01/95 to 09/30/96
Outputs
The objective of our research is to understand how sex is determined in plants using a model plant system, the fern Ceratopteris. We have used a genetic approach to isolate mutations that affect the sex of the Ceratopteris gametophyte. Normally, the sex of the gametophyte is either male or hermaphroditic. The determinant of sex type is the pheromone antheridiogen which is secreted by the hermaphrodite and induces male development of immature gametophytes. The mutants we have isolated include the hermaphroditic mutants which cannot respond to the pheromone and are always hermaphroditic; a femininization mutant which cannot produce sperm-forming antheridia; and a transformer mutant which is male even in the absence of the male-inducing pheromone. Each of these mutations defines key regulatory genes necessary for appropriate sex expression in this organism. By making double and triple mutant gametophyes for each of these genes, we have shown that these genes interact
with one another in a simple regulatory pathway.
Impacts
(N/A)
Publications
- Cooke, T., L. Hickok, W. VanDer Woude, J. Banks and R. Scott. 1993. Photobiological characterization of a spore germination mutant dkg1 with reversed photoregulation in the fern Ceratopteris. Photochem. and Photobiol. 57:1032-1041.
- Banks, J., L. Hickok and M.A. Webb. 1993. Programming of sexual phenotype in the homosporous fern, Ceratopteris richardii. Inter. J. Plant Sci. 154:522-534.
- Banks, J. 1994. Sex-determining genes in the homosporous fern Ceratopteris. Development 120:1949-1958.
- Eberle, J., J. Nemacheck, C. Wen, M. Hasebe and J. Banks. 1994. Ceratopteris: a model system for studying sex-determining mechanisms in plants. Int. J. Plant Sci. 156:359-366.
- Eberle, J. and J. Banks. 1996. Genetic interactions among sex determining genes in the fern Ceratopteris. Genetics 142:973-985.
- Banks, J. 1997. Sex determination in ferns: the battle between the sexes. Reviews in Plant Science, invited review submitted.
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Progress 10/01/94 to 09/30/95
Outputs
The objective of our research is to understand how sex is determined in plants using a model plant system, the fern Ceratopteris. We have used a genetic approach to isolate mutations that affect the sex of the Ceratopteris gametophyte. Normally, the sex of the gametophyte is either male or hermaphroditic. The determinant of sex type is the pheromone antheridiogen which is secreted by the hermaphrodite and induces male development of immature gametophytes. The mutants we have isolated include the hermaphroditic mutants which cannot respond to the pheromone and are always hermaphroditic; a femininization mutant which cannot produce sperm-forming antheridia; and a transformer mutant which is male even in the absence of the male-inducing pheromone. Each of these mutations defines key regulatory genes necessary for appropriate sex expression in this organism. By making double and triple mutant gametophyes for each of these genes, we have shown that these genes interact with
one another in a simple regulatory pathway.
Impacts
(N/A)
Publications
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Progress 10/01/93 to 09/30/94
Outputs
The objective of our research is to understand how sex is determined in plants using a model plant system, the fern Ceratopteris. We have used a genetic approach to isolate mutations that affect the sex of the Ceratopteris gametophyte. Normally, the sex of the gametophyte is either male or hermaphroditic. The determinant of sex type is the pheromone antheridiogen which is secreted by the hermaphrodite and induces male development of immature gametophytes. The mutants we have isolated include the hermaphroditic ected and selfed in BSP3 (S2). the pheromone and are always hermaphroditic; a femininization mutant which cannot produce sperm-forming antheridia; and a transformer mutant which is male even in the absence of the male-inducing pheromone. Each of these mutations defines key regulatory genes necessary for appropriate sex expression in this organism. By making double and triple mutant gametophytes for each of these genes, we have shown that these genes interact with
one another in a simple regulatory pathway. In order to know how many genes are involved in regulating sex-determination in Ceratopteris, we have begun to test how well our mutagenesis has saturated the sex-determining pathway. We are also generating tetraploid sporophyte plants (a process referred to as apospory) which will produce diploid gametophyte plants, a condition necessary for determining whether any of the mutants described above are dominant or recessive.
Impacts
(N/A)
Publications
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Progress 10/01/92 to 09/30/93
Outputs
The primary objective of our project is to gain an understanding of the molecular mechanisms involved in sex determination in plants using a model plant system. Our objective was to identify and characterize genes in the homosporous fern Ceratopteris richardii that are involved in controlling sex determination by the male-inducing pheromone antheridiogen. In the wild type, hermaphrodites secrete the pheromone although they are insensitive to its effect. Sexually immature individuals respond to the pheromone secreted by the hermaphrodite and develop as males. To date, we have isolated a total of 24 different mutants. These mutants fall into four categories. The hermaphroditic (her) mutants always develop as hermaphrodites. The function of the wild type HER genes is to promote male development and suppress female development. These mutations probably affect genes that either encode the receptor of antheridiogen, or are involved in the antheridiogen signal transduction
pathway. The second class of mutants are the transformer (tra) mutants. These mutants are always male. The functional wild type TRA gene is necessary for female development. The feminization (fem) mutation is always female. Its gene product is necessary for male development. The final class of mutants (abi) are insensitive to ABA. ABA normally blocks the Ace response.
Impacts
(N/A)
Publications
- BANKS, J., HICKOK, L. and WEBB. 1993. The programming of sexual phenotype in the homosporous fern, Ceratopteris richardii. Int. J. Plant Sci. in-press.
- COOKE, T., HICKOK, L., VANDERWOUDE, W., BANKS, J. and R. SCOTT. 1993. Photobiological characterization of a spore germination mutant dkg1 with reversed photoregulation in the fern Ceratopteris richardii. Photochem. and Photobiol. 57:1032-.
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Progress 10/01/91 to 09/30/92
Outputs
The objectives of our research this past year have been: 1) to identify and characterize genetic mutants of the homosporous fern Ceratopteris richardii that result in an altered sexual phenotype in the gametophyte; 2) to investigate the epistatic interactions among these genes; 3) to identify and characterize genes that are induced or repressed in response to the sex determining pheromone, antheridiogen. Objective 1 has been achieved in the past year by selecting mutagenized gametophytes that have an altered sexual phenotype in response to the pheromone, antheridiogen. In the absence of pheromone, normal gametophytes develop as hermaphrodites while in its presence they develop as males. Four classes of sex-determining mutants have thus far been identified. Objective 2 will be addressed by genetically producing gametophytes that contain two or three of these mutations. The sexual phenotype of plants containing two or three mutant genes will tell us whether and perhaps
how the two or three genes interact with one another in determining the sex of the gametophyte. The third objective is being addressed by a technique referred to as a "gene expression screen". In this screen, messenger RNA (mRNA) that is either present or absent only after adding the sex-determining pheromone will be isolated from a total mRNA population by subtractive hybridization. mRNAs thus identified are likely to be genes that are directly involved in the decision to develop as either a male or a hermaphrodite. To determine t.
Impacts
(N/A)
Publications
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