Dr Lynette Brownfield
|Department||Department of Biochemistry|
|Research summary||Plant biochemistry|
Plant sexual reproduction
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.
Enquires about projects from prospective graduate students and postdoctoral fellows are welcome.
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
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
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