Progress 10/01/19 to 09/30/20
Outputs
Target Audience:Scientists investigating plant reproduction or genome evolution Changes/Problems:Problems requiring a redirection of our efforts have not been encountered. What opportunities for training and professional development has the project provided?All three of the journal articles published this year report research findings that were largely made and elucidated by undergraduate or graduate students. These students participated in preparing and writing up their findings for publication and are included as authors on the papers. The project helped fund the presentation of our findings at the Plant and Animal Genome meetings in San Diego in January, and one of our undergraduate students presented his research findings at the American Society of Plant Biologists online meeting in Washington DC. Two undergraduate students in my lab applied for and obtained PhD program research assistantships, both in biochemistry, at the University of Utah and the University of Nevada, Reno. Much professional development, in terms of understanding and applying molecular biology, is occurring as a result of multiple informal one-on-one meetings and discussions among molecular biology trained professors in the department. How have the results been disseminated to communities of interest?In addition to the published papers and abstracts mentioned above, descriptive materials regarding our recent publications and patent filing have been disseminated to potentially interested seed companies. What do you plan to do during the next reporting period to accomplish the goals?Our work for the coming year will focus on objective 3, combine selected promoters and candidate genes into transformation constructs, and 4, engineering the designed cassettes into Arabidopsis and evaluating their effects in terms of inducing apomeiosis, parthenogenesis and autonomous endosperm formation in this taxon. We recently received additional funding to extend these reproductive analyses and transformation efforts to maize.
Impacts
What was accomplished under these goals?
Major activities completed.A major project linking gene expression profiling of floral tissues of sexual and apomictic plants with in vitro and in situ functional analyses of the implied molecular pathways was completed and published (doi:10.3390/genes11121449). Results and key impacts are described below. Specific objectives met. Objective 1: select and clone apomixis candidate genes. Sixteen genes that regulate metabolic homeostasis were selected as candidate genes. These were chosen because i) they were differentially expressed between ovules of sexual and apomictic plants, and ii) studies involving pharmacological chemicals that affect the metabolic pathways that these 16 genes regulate were successful in switching sexual (reduced) gametophyte and egg formation to apomictic (unreduced) gametophyte and egg formation in five sexual species from three angiospermous families. Six of these genes have been identified for cloning and transformation experiments. Objective 2: select and obtain promoters. Two tissue specific promoters have been selected for transformation experiments. Significant results achieved, including major findings, developments, or conclusions (both positive and negative). Across expression profiling comparisons, 3723 differentially expressed genes were identified, which were linked to 3980 gene ontology (GO) terms. Additionally, 1773 enriched GO terms were identified across comparisons. GO terms were assigned to user defined subgroups. Chi square analyses of these subgroups among comparisons revealed major shifts in gene expression between ovules of sexual and apomictic plants. Specifically, Genes associated with translation, cell division, epigenetic silencing, flowering, and meiosis characterized sexual Boechera(meiotic). In contrast, genes associated with stress responses, abscisic acid signaling, reactive oxygen species production, and stress attenuation mechanisms characterized apomictic Boechera (apomeiotic). These metabolic differences were found to regulate reproductive mode. Apomeiosis switched to meiosis when premeiotic ovules of apomicts were cultured on media that increased oxidative stress. In contrast, meiosis switched to apomeiosis when premeiotic pistils of sexual plants were cultured on media that relieved oxidative stress. High?frequency apomeiosis was initiated in all sexual species tested: Brassicaceae, Boechera stricta, Boechera exilis, and Arabidopsis thaliana; Fabaceae, Vigna unguiculata; Asteraceae, Antennaria dioica. Unreduced gametophytes formed from ameiotic female and male sporocytes, first division restitution dyads, and nucellar cells. These results are consistent with modes of reproduction and types of apomixis, in natural apomicts, being regulated metabolically (doi:10.3390/genes11121449). Key impacts or other accomplishments realized.Two important barriers have frustrated the development of apomixis as a technology for stabilizing hybrid vigor in crops: (i) understanding what apomixis is biologically, and (ii) understanding what biological properties trigger meiosis/apomeiosis interconversions. Concerning the first, we demonstrated that apomeiosis does not require mutations, meiotic or otherwise, but is instead a polyphenism of meiosis, i.e., switching from apomeiosis to meiosis in apomictic plants and from meiosis to apomeiosis in sexual plants was readily achieved through appropriate chemical treatments. Concerning the second, we demonstrated that polyphenic shifts from apomeiosis to meiosis or vice versa are metabolically regulated. Here, megaspore mother cells (MMCs) of apomictic taxa reverted to meiosis at high frequencies when exposed to meiosis promoting metabolic conditions. Likewise, MMCs, nucellar cells, and/or microsporocytes from sexual taxa reverted to apomeiosis at high frequencies when exposed to apomeiosis promoting metabolic conditions. That meiosis can be switched to apomeiosis in sexual plants represents a key impact that may enable the rapid development of apomictic crops that preserve hybrid vigor from one seed generation to the next.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2020
Citation:
Mandakova, T., Hlouskova, P., Windham, M. D., Mitchell-Olds, T., Ashby, K., Price, B., Carman, J. G., & Lysak, M. A. (2020, May 28). Chromosomal evolution and apomixis in the cruciferous tribe Boechereae. Frontiers in Plant Science, 11(514).
- Type:
Journal Articles
Status:
Published
Year Published:
2020
Citation:
de Mateo Arias, M., Gao, L., Sherwood, D. A., Dwivedi, K. K., Price, B. J., Jamison, M., Kowallis, B. M., & Carman, J. G. (2020, December 02). Whether Gametophytes are Reduced or Unreduced in Angiosperms Might Be Determined Metabolically. Genes, 11(12).
- Type:
Other
Status:
Other
Year Published:
2020
Citation:
Carman, J. G., Price, B. J., Gao, L., Sherwood, D. A., & Mateo de Arias, M. (2020). Meiosis to Apomeiosis Switching Is Metabolically Inducible in Angiosperms. www.scherago.com: Plant and Animal Genome XXVIII Meetings.
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Progress 10/01/18 to 09/30/19
Outputs
Target Audience:Academic, plant evolutionary and reproductive biology; industry, plant breeding and genetics, commercial seed companies Changes/Problems:Problems requiring a redirection of our efforts have not been encountered. What opportunities for training and professional development has the project provided?Two of the three journal articles published this year contain research discoveries made and elucidated by undergraduate students. These students were involved in preparing and writing up their findings for publication, and they are included as authors on these papers. Our project also provided for myself, a recently graduated Ph.D. student, and an undergraduate student several additional professional development opportunities. The three of us presented papers at the Plant and Animal Genome meetings in San Diego in January, two oral presentations and one poster presentation. The undergraduate student also presented his research findings at the American Society of Plant Biologists (ASPB) meeting in San Jose. This student used his findings and those of the lab collectively to write, last spring, a summer internship proposal to ASPB, which was funded. It was one of 14 proposals total that were selected for funding. The PSC department recently added to its faculty a well-trained plant molecular biologist who is sharing our lab with us. Much professional development, in terms of understanding and applying molecular biology, is occurring as a result of multiple informal one-on-one meetings and discussions with this new professor. How have the results been disseminated to communities of interest?In addition to the published papers and abstracts mentioned above, descriptive materials regarding our recent patent filing are being developed for dissemination to potentially interested seed companies. What do you plan to do during the next reporting period to accomplish the goals?Our work for the coming year will continue to focus on objectives 1-4: selecting candidate genes, acquiring appropriate promoters for tissue specific expression, combining promoters and candidate genes into transformation constructs, and engineering the constructs into Arabidopsis. We recently received tentative approval of a grant proposal that will extend these reproductive analyses and transformation efforts to maize.
Impacts
What was accomplished under these goals?
Our 2019 research focused on objectives 1-2: selecting candidate genes and acquiring appropriate promoters. Several candidate genes were selected based on a reanalysis of previously obtained transcriptome data using updated gene information releases from Panther, Araport11 and TAIR. One gene and one tissue specific promoter were successfully cloned. We also conducted additional in vitro studies to further identify molecular pathways responsible for meiosis to apomeiosis switching in Arabidopsis using chemicals associated with specific cell signaling mechanisms. Two of these chemicals were effective in switching meiosis to apomeiosis. Results of these studies are currently being prepared for journal article submittal. Our research focuses on a new hypothesis for the origins and regulation of asexual seed formation, which we developed. This hypothesis is described in a 2019 article in the Journal of Experimental Botany. We also completed a cytological documentation of sexual and apomictic development in all major taxonomic divisions of the genus Boechera (Brassicaceae), which was published in 2019 in Frontiers of Plant Science. This article also presents strong evidence for evolution of sexual species from apomicts. We also documented for the first time the mode of reproduction in the genus Phoenicaulis (Brassicaceae). Interestingly, all sampled material from three ploidy levels, including diploids, were apomictic. This work was published in 2019 in the Journal of Systematics and Evolution.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2019
Citation:
Albertini, E., Barcaccia, G., Carman, J. G., & Pupilli, F. (2019, March 11). Did apomixis evolve from sex or was it the other way around? Journal of Experimental Botany, 70(11), 29512964
- Type:
Journal Articles
Status:
Published
Year Published:
2019
Citation:
Carman, J. G., Mateo de Arias, M., Gao, L., Zhao, X., Kowallis, B. M., Sherwood, D. A., Srivastava, M. K., Dwivedi, K. K., Price, B. J., Watts, L., & Windham, M. D. (2019, May 31). Apospory and diplospory in diploid Boechera (Brassicaceae) may facilitate speciation by recombination-driven apomixis-to-sex reversals. Frontiers in Plant Science, 10(May 2019), 724.
- Type:
Journal Articles
Status:
Published
Year Published:
2019
Citation:
Mand�kov�, T., Ashby, K., Price, B. J., Windham, M. D., Carman, J. G., & Lysak, M. A. (2019, December 10). Genome structure and apomixis in Phoenicaulis (Brassicaceae; Boechereae). Journal of Systematics and Evolution.
- Type:
Other
Status:
Published
Year Published:
2019
Citation:
Carman, J. G., & Lacey, J. (2019). Bioenergetic Activity is Correlated with Apomeiosis in Sorghum Ovules. GEO publications: NCBI Gene Expression Omnibus
- Type:
Other
Status:
Published
Year Published:
2019
Citation:
Carman, J. G., Gao, L., Sherwood, D. A., Mateo de Arias, M., & Price, B. J. (2019). Wanting to induce high frequency Antennaria-type diplospory, Taraxacum-type diplospory or Hieracium-type apospory in crops? Its your choice. International Plant and Animal Genome XXVII Conference, San Diego, CA.
- Type:
Other
Status:
Published
Year Published:
2019
Citation:
Gao, L., Price, B. J., Sherwood, D. A., & Carman, J. G. (2019). Switching apomixis to sex in Boechera. Components of Apomixis Workshop, International Plant & Animal Genome XXVII Conference, San Diego, CA, January 12-16.
- Type:
Other
Status:
Published
Year Published:
2019
Citation:
Price, B. J., & Carman, J. G. (2019). Inducing apomeiosis and disrupting meiotic reduction in gametes of sexual Antennaria (Asteraceae) and Arabidopsis thaliana (Brassicaceae). Plant Biology 2019. Annual Meeting of the American Society of Plant Biologists, San Jose, CA, Aug. 3-7.
- Type:
Other
Status:
Published
Year Published:
2019
Citation:
Sherwood, D. A., Gao, L., Mateo de Arias, M., Price, B. J., & Carman, J. G. (2019). Pharmacologically induced apomixis in Boechera, Arabidopsis and Vigna: longstanding theories of apomixis origins and regulation are contradicted. Components of Apomixis Workshop, International Plant & Animal Genome XXVII Conference, San Diego, CA, January 12-16.
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Progress 07/01/18 to 09/30/18
Outputs
Target Audience:Academic: plant evolutionary and reproductive biology Industry: Plant breeding and genetics, commercial seed companies Changes/Problems:No changes. What opportunities for training and professional development has the project provided?Professional development in the areas of i) statistical analyses of large expression profiling data sets and ii) bioinformatic analyses of expression profiling data occurred through multiple one-on-one meetings and discussions with two faculty collaborators, a statistician and a bioinformatics scientist. How have the results been disseminated to communities of interest?Preliminary materials to be disseminated to seed companies regarding our provisional patent have been developed and are being refined. The target audiences for these materials are large international seed companies. What do you plan to do during the next reporting period to accomplish the goals?Our work for the coming year will focus on objectives 1-4: selecting candidate genes, acquiring appropriate promoters for tissue specific expression, and combining promoters and candidate genes into transformation constructs, and engineering the constructs into Arabidopsis.
Impacts
What was accomplished under these goals?
This is a new project as of July 1. Major activities completed related to objective 1 (selecting candidate genes for transformation studies): Additional pharmacological tests of our molecular model for apomixis sex switching were successfully completed in our lab using sexual plants. The induction of moderate to high frequency apomeiosis (unreduced, asexual egg formation) in these completely sexual plants was observed in each case (provisional patent was filed earlier in the year). We also identified a new plant species to serve as a model for inducing apomeiosis and parthenogenesis and have completed initial tests to verify that flowering can be induced and sustained in vitro.
Publications
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2018
Citation:
Carman, J. G., Plant and Animal Genome Meetings, "Can Infrequent Chromosome Pairing and Segregation in Allodiploid Apomictic Boechera produce Genomically Unique Sexual Species?," San Diego. (January 11, 2018 - January 15, 2018)
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