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Department of Biochemistry profile

Associate Professor Lynette Brownfield

PositionAssociate Professor
DepartmentDepartment of Biochemistry
QualificationsBSc(Hons) PhD
Research summaryPlant biochemistry

Research

Plant sexual reproduction

Scientific image.
An Arabidopsis pollen grain (male gametophyte) with a large vegetative cell (wall shown in red) containing a vegetative cell nucleus (vn) and two sperm cell nuclei (sn) labeled with a histone-GFP fusion protein.

Like in animals, sexual reproduction in flowering plants relies upon the production of male (sperm) and female (eggs) gametes and their fusion upon fertilization. Despite the importance of plant fertility for seed production and agricultural productivity, relatively little is known about the molecular processes underlying gamete development and function. Work in my lab is focused on using genetic and molecular approaches to understand key stages of male gametophyte (pollen) and sperm cell development.

Plant male meiosis and the formation of unreduced gametes

Polyploidy, the presence of more than two sets of chromosomes, has had a major impact upon the evolution of plants and the development of modern agricultural crop varieties. The major mechanism of polyploid formation is believed to be through the production of gametes that have not had their ploidy level reduced during meiosis and are thus termed unreduced. We use a mutant, called jason, in the model plant Arabidopsis thaliana to investigate how unreduced gametes form.

We have found that cytoplasmic organisation is essential in preventing unreduced male gamete formation. In particular, a band of organelle that forms across the middle of meiotic cells during the second division is important as it provides a physical barrier to keep the two meiotic spindles separated. We are now investigating how the molecular function of the JASON protein to determine how it impacts upon cytoplasmic organisation.

Specification of the male germ line in Arabidopsis

In flowering plants the male germ line is not formed until late in development when a haploid microspore undergoes a highly asymmetric division. This forms a large vegetative cell and a smaller germ cell, which represents the start of the male germ line. During germ-line development the germ cells is engulfed within the cytoplasm of the vegetative cell where it expresses the proteins required for sperm cell function and undergoes a single mitotic division. We are interested in how the asymmetric division specifies the male germ line, largely by investigating the regulation of the key germ-line transcription factor DUO1.

Positions

Enquires about projects from prospective graduate students and postdoctoral fellows are welcome. Information about scholarships for New Zealand postgraduate students go to the University of Otago website:.

Postgraduate and scholarship awards

Awards

Ben Peters

2016, Department of Biochemistry Best Student Paper, 1st place

For the paper: A cis-regulatory module in the transcription factor DUO1 promoter. Benjamin Peters, Jonathan Casey, Jack Aidley, Stuart Zohrab, Michael Borg, David Twell, and Lynette Brownfield., Plant Physiol 2016 p. pp.01192.2016. Published:16 November 2016 Abstract: The development of the male germline within pollen relies upon the activation of numerous target genes by the transcription factor DUO POLLEN1 (DUO1). The expression of DUO1 is restricted to the male germline and is first detected shortly after the asymmetric division that segregates the germ cell lineage. Transcriptional regulation is critical in controlling DUO1 expression since transcriptional and translational fusions show similar expression patterns. Here we identify key promoter sequences required for the germline-specific regulation of DUO1 transcription. Combining promoter deletion analyses with phylogenetic footprinting in eudicots and in Arabidopsis accessions, we identify a cis-regulatory module, Regulatory region of DUO1 (ROD1), which replicates the expression pattern of DUO1 in Arabidopsis thaliana. We show that ROD1 from the legume Medicago truncatula directs male germline-specific expression in A. thaliana, demonstrating conservation of DUO1 regulation among eudicots. ROD1 contains several short conserved cis-regulatory elements, including three copies of the motif DNGTGGV, required for germline expression and tandem repeats of the motif YAACYGY, which enhance DUO1 transcription in a positive feedback loop. We conclude that a cis-regulatory module conserved in eudicots, directs the spatial and temporal expression of the transcription factor DUO1 to specify male germline fate and sperm cell differentiation.

Ben Peters

2015, New Zealand Society of Plant Biologists Best Student Presentation at ComBio, 1st place

Publications

Herridge, R., McCourt, T., Jacobs, J. M. E., Mace, P., Brownfield, L., & Macknight, R. (2022). Identification of the genes at S and Z reveals the molecular basis and evolution of grass self-incompatibility. Frontiers in Plant Science, 13, 1011299. doi: 10.3389/fpls.2022.1011299

Brownfield, L. (2022). Pollen helps reveal a role for DC1 domain proteins. Plant & Cell Physiology. Advance online publication. doi: 10.1093/pcp/pcac148

Yi, J., Kradolfer, D., Brownfield, L., Ma, Y., Piskorz, E., Köhler, C., & Jiang, H. (2022). Meiocyte size is a determining factor for unreduced gamete formation in Arabidopsis thaliana. New Phytologist. Advance online publication. doi: 10.1111/nph.18473

Tahir, J., Crowhurst, R., Deroles, S., Hilario, E., Deng, C., Schaffer, R., Le Lievre, L., … Brownfield, L. R., … Pilkington, S. M. (2022). First chromosome-scale assembly and deep floral-bud transcriptome of a male kiwifruit [Data report]. Frontiers in Genetics, 13, 852161. doi: 10.3389/fgene.2022.852161

Brownfield, L. (2021). Plant breeding: Revealing the secrets of cytoplasmic male sterility in wheat [Dispatch]. Current Biology, 31(11), R724-R726. doi: 10.1016/j.cub.2021.04.026

Cridge, A. G., Dearden, P. K., & Brownfield, L. R. (2019). The developmental hourglass in the evolution of embryogenesis. In L. N. de la Rosa & G. Müller (Eds.), Evolutionary developmental biology: A reference guide. Cham, Switzerland: Springer. doi: 10.1007/978-3-319-33038-9

Chapter in Book - Research

Peters, B., Aidley, J., Cadzow, M., Twell, D., & Brownfield, L. (2017). Identification of cis-regulatory modules that function in the male germline of flowering plants. In A. Schmidt (Ed.), Plant germline development: Methods and protocols: Methods in molecular biology (Vol. 1669). (pp. 275-293). Springer. doi: 10.1007/978-1-4939-7286-9_22

Chapter in Book - Research

Twell, D., & Brownfield, L. (2017). Analysis of fluorescent reporter activity in the male germline during pollen development by confocal microscopy. In A. Schmidt (Ed.), Plant germline development: Methods and protocols: Methods in molecular biology (Vol. 1669). (pp. 67-75). Springer. doi: 10.1007/978-1-4939-7286-9_6

Chapter in Book - Research

Brownfield, L., & Twell, D. (2016). Plant Reproduction. In eLS. Chichester, UK: John Wiley & Sons. doi: 10.1002/9780470015902.a0002046.pub2

Chapter in Book - Research

Brownfield, L., Doblin, M. A., Fincher, G. B., & Bacic, A. (2009). Biochemical and molecular properties of biosynthetic enzymes for (1,3)-ß-glucans in embryophytes, chlorophytes and rhodophytes. In A. Bacic, G. B. Fincher & B. A. Stone (Eds.), Chemistry, biochemistry, and biology of (1→3)-β-glucans and related polysaccharides. (pp. 283-326). Burlington, MA: Academic Press.

Chapter in Book - Research

Herridge, R., McCourt, T., Jacobs, J. M. E., Mace, P., Brownfield, L., & Macknight, R. (2022). Identification of the genes at S and Z reveals the molecular basis and evolution of grass self-incompatibility. Frontiers in Plant Science, 13, 1011299. doi: 10.3389/fpls.2022.1011299

Journal - Research Article

Yi, J., Kradolfer, D., Brownfield, L., Ma, Y., Piskorz, E., Köhler, C., & Jiang, H. (2022). Meiocyte size is a determining factor for unreduced gamete formation in Arabidopsis thaliana. New Phytologist. Advance online publication. doi: 10.1111/nph.18473

Journal - Research Article

Herridge, R., Samarth, Brownfield, L., & Macknight, R. (2021). Identification and characterization of perennial ryegrass (Lolium perenne) vernalization genes. Frontiers in Plant Science, 12, 640324. doi: 10.3389/fpls.2021.640324

Journal - Research Article

Rossig, C., Le Lievre, L., Pilkington, S. M., & Brownfield, L. (2021). A simple and rapid method for imaging male meiotic cells in anthers of model and non-model plant species [Method paper]. Plant Reproduction, 34, 37-46. doi: 10.1007/s00497-021-00404-5

Journal - Research Article

Herridge, R. P., Macknight, R. C., & Brownfield, L. R. (2020). Prospects for F1 hybrid production in ryegrass. New Zealand Journal of Agricultural Research, 63(3), 405-415. doi: 10.1080/00288233.2018.1559867

Journal - Research Article

Cabout, S., Leask, M. P., Varghese, S., Yi, J., Peters, B., Conze, L. L., … Brownfield, L. (2017). The meiotic regulator JASON utilizes alternative translation initiation sites to produce differentially localized forms. Journal of Experimental Botany, 68(15), 4205-4217. doi: 10.1093/jxb/erx222

Journal - Research Article

Peters, B., Casey, J., Aidley, J., Zohrab, S., Borg, M., Twell, D., & Brownfield, L. (2017). A conserved cis-regulatory module determines germline fate through activation of the transcription factor DUO1 promoter. Plant Physiology, 173, 280-293. doi: 10.1104/pp.16.01192

Journal - Research Article

Cridge, A. G., Dearden, P. K., & Brownfield, L. R. (2016). Convergent occurrence of the developmental hourglass in plant and animal embryogenesis? Annals of Botany, 117(5), 833-843. doi: 10.1093/aob/mcw024

Journal - Research Article

Brownfield, L., Yi, J., Jiang, H., Minina, E. A., Twell, D., & Köhler, C. (2015). Organelles maintain spindle position in plant meiosis. Nature Communications, 6, 6492. doi: 10.1038/ncomms7492

Journal - Research Article

Borg, M., Brownfield, L., Khatab, H., Sidorova, A., Lingaya, M., & Twell, D. (2011). The R2R3 MYB transcription factor DUO1 activates a male germline-specific regulon essential for sperm cell differentiation in Arabidopsis. Plant Cell, 23(2), 534-549. doi: 10.1105/tpc.110.081059

Journal - Research Article

Brownfield, L., & Köhler, C. (2011). Unreduced gamete formation in plants: Mechanisms and prospects. Journal of Experimental Botany, 62(5), 1659-1668. doi: 10.1093/jxb/erq371

Journal - Research Article

Borg, M., Brownfield, L., & Twell, D. (2009). Male gametophyte development: A molecular perspective. Journal of Experimental Botany, 60(5), 1465-1478. doi: 10.1093/jxb/ern355

Journal - Research Article

Brownfield, L., Hafidh, S., Borg, M., Sidorova, A., Mori, T., & Twell, D. (2009). A plant germline-specific integrator of sperm specification and cell cycle progression. PLoS Genetics, 5(3), e1000430. doi: 10.1371/journal.pgen.1000430

Journal - Research Article

Brownfield, L., Hafidh, S., Durbarry, A., Khatab, H., Sidorova, A., Doerner, P., & Twell, D. (2009). Arabidopsis DUO POLLEN3 is a key regulator of male germline development and embryogenesis. Plant Cell, 21(7), 1940-1956. doi: 10.1105/tpc.109.066373

Journal - Research Article

Erilova, A., Brownfield, L., Exner, V., Rosa, M., Twell, D., Mittelsten Scheid, O., … Köhler, C. (2009). Imprinting of the Polycomb group gene MEDEA serves as a ploidy sensor in Arabidopsis. PLoS Genetics, 5(9), e1000663. doi: 10.1371/journal.pgen.1000663

Journal - Research Article

Schoft, V. K., Chumak, N., Mosiolek, M., Slusarz, L., Komnenovic, V., Brownfield, L., … Tamaru, H. (2009). Induction of RNA-directed DNA methylation upon decondensation of constitutive heterochromatin. EMBO Reports, 10(9), 1015-1021. doi: 10.1038/embor.2009.152

Journal - Research Article

Brownfield, L., Wilson, S., Newbigin, E., Bacic, A., & Read, S. (2008). Molecular control of the glucan synthase-like protein NaGSL1 and callose synthesis during growth of Nicotiana alata pollen tubes. Biochemical Journal, 414(1), 43-52. doi: 10.1042/bj20080693

Journal - Research Article

Kim, H. J., Oh, S. A., Brownfield, L., Hong, S. H., Ryu, H., Hwang, I., … Nam, H. G. (2008). Control of plant germline proliferation by SCFFBL17 degradation of cell cycle inhibitors. Nature, 455(7216), 1134-1137. doi: 10.1038/nature07289

Journal - Research Article

Töller, A., Brownfield, L., Neu, C., Twell, D., & Schulze-Lefert, P. (2008). Dual function of Arabidopsis glucan synthase-like genes GSL8 and GSL10 in male gametophyte development and plant growth. Plant Journal, 54(5), 911-923. doi: 10.1111/j.1365-313X.2008.03462.x

Journal - Research Article

Brownfield, L., Ford, K., Doblin, M. S., Newbigin, E., Read, S., & Bacic, A. (2007). Proteomic and biochemical evidence links the callose synthase in Nicotiana alata pollen tubes to the product of the NaGSL1 gene. Plant Journal, 52(1), 147-156. doi: 10.1111/j.1365-313X.2007.03219.x

Journal - Research Article

Farrokhi, N., Burton, R. A., Brownfield, L., Hrmova, M., Wilson, S. M., Bacic, A., & Fincher, G. B. (2006). Plant cell wall biosynthesis: Genetic, biochemical and functional genomics approaches to the identification of key genes. Plant Biotechnology Journal, 4(2), 145-167. doi: 10.1111/j.1467-7652.2005.00169.x

Journal - Research Article

Brownfield, L. (2022). Pollen helps reveal a role for DC1 domain proteins. Plant & Cell Physiology. Advance online publication. doi: 10.1093/pcp/pcac148

Journal - Research Other

Tahir, J., Crowhurst, R., Deroles, S., Hilario, E., Deng, C., Schaffer, R., Le Lievre, L., … Brownfield, L. R., … Pilkington, S. M. (2022). First chromosome-scale assembly and deep floral-bud transcriptome of a male kiwifruit [Data report]. Frontiers in Genetics, 13, 852161. doi: 10.3389/fgene.2022.852161

Journal - Research Other

Brownfield, L. (2021). Plant breeding: Revealing the secrets of cytoplasmic male sterility in wheat [Dispatch]. Current Biology, 31(11), R724-R726. doi: 10.1016/j.cub.2021.04.026

Journal - Research Other

Brownfield, L., & Twell, D. (2009). A dynamic DUO of regulatory proteins coordinates gamete specification and germ cell mitosis in the angiosperm male germline [Article addendum]. Plant Signaling & Behavior, 4(12), 1159-1162.

Journal - Research Other

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