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Department of Biochemistry profile

Dr Lynette Brownfield

PositionLecturer
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.

Publications

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

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

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

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

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

Chapter in Book - Research

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

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.

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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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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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.

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