Prof Rod Scott
Professor3 South, 1.18 R.J.Scott@bath.ac.uk Tel.: 01225 38 3437 Fax: 01225 38 6779
- 2001-present Professor of Biology, Department of Biology & Biochemistry, University of Bath.
- 1998-2001 Lecturer, Senior Lecturer, Department of Biology & Biochemistry, University of Bath.
- 1995-1997 Lecturer, Department of Biology, University of Leicester.
- 1992-1995 Research Lecturer, Department of Botany, Universty of Leicester.
- 1984-1992 Research Assistant, Department of Botany, University of Leicester.
- 1984- PhD Botany, University of Nottingham.
1- Algae Biotechnology
Single-celled, or microalgae, are a very diverse group of species with many potential applications including the production of biofuels, pigments, protein for animal feed and industrial feedstocks. Their mass culture could also help capture harmful CO2 to combat climate change and to clean wastewater to reduce environmental damage.
Before algae can realize this potential a number of technical challenges must be overcome, such as thermo-tolerance, increased photosynthetic efficiency and reduced harvesting and product recovery costs. These challenges are the focus of several projects in the lab.
Thermo-tolerance – Roman algae
The large-scale culture of algae is likely to take place in regions with high light intensities in order to maximize photosynthetic yield. With light comes heat. However, most algae species have relatively low temperature optima for growth and are therefore likely to perform poorly in such production systems. Our ‘Roman algae’
project is attempting to identify thermo-tolerant species that synthesize useful products, including the precursors of biodiesel. The water within the Roman baths in Bath city centre is green due to the presence of microalgae. There are two different baths: the ‘King’s Bath’ is at 39oC and the ‘Great Bath’ is at 39oC; both have remained constant for many years. Bioprospecting coupled to rDNA bar-coding has identified seven different species of algae. The next steps in the project include: evaluating the ability of the Roman algae species to synthesize biodiesel precursors at elevated temperatures; searching for other valuable chemical compounds using analytical chemistry techniques, such as GC-MS and determining which most suits potential future mass growth for biodiesel production.
Increased photosynthetic efficiency and reduced product recovery costs
The Denso Corporation of Japan is attempting to use a particular species of microalgae (Pseudochoricystis ellipsoidea) to capture CO2 emissions from its factories and to recover biodiesel from the resulting algal biomass. In common with most wild algae species, the photosynthetic apparatus of P. ellipsoidea is optimized for operation across a range of light intensities. Consequently, these unmodified strains have more chlorophyll than is required for optimum performance in commercial culture systems, such as shallow raceway ponds or photobioreactors (PBRs), where light is not limiting. This reduces the overall photosynthetic efficiency of the culture due to mutual shading, where algal cells close to the surface intercept more light that they can use, and thereby shade algae deeper in the culture. On objective of this project is to develop strains with reduced chlorophyll content using mutation breeding. These will be evaluated for improved productivity in both raceway ponds and PBRs in facilities located within the Biology and Biochemistry Department. Mutation breeding is also being applied to improve the recovery of oil from the algae by generating strains with reduced cell wall strength.
Cleaning wastewater and reducing the cost of algae biomass production
Water utility companies are under intense and growing pressure to reduce the environmental impacts of wastewater treatment, caused principally by excess nitrates and phosphates. At the same time there is demand for sustainable production of biomass for diverse uses, including feed, chemicals and liquid fuels. This project which is part funded by Aragreen (UK) Ltd and the EPSRC addresses both issues by developing methods to cultivate algal biomass in wastewater, supplemented with other waste streams, and utilizing LEDs to provide energy efficient light for growth. The removal of nitates and phosphates from wastewater in sewage works is often an energy intensive process, which relies on chemical inputs and produces CO2and other wastes. Since
nitrates and phosphates (together with CO2 and light) are key feedstocks for algal biomass production, the system we are developing aims to reduce both water treatment costs and the cost of products extracted from algal biomass.
The project has established a pilot scale facility based at Stowfield in South Gloucestershire featuring a large PBR, state-of-the-art lighting and harvesting equipment and a link to a near-by wastewater treatment works operated by Welsh water. The objective is to demonstrate the feasibility of wastewater treatment using algae by transferring knowledge gained in lab scale experiments conducted at Bath to this much larger and more challenging scale.
2- Plant Biotechnology
Harnessing genetic variation for seed size and hybridization barriers in Arabidopsis thaliana
Seeds are the most important agricultural product, accounting for at least 70% of the world’s food supply (either directly or as animal feed). With rising population and diminishing availability of agricultural land, it is increasingly urgent to improve crop yields; increasing seed size is one route to this goal. A major interest in the lab is the mechanism of seed growth regulation. We are investigating this from several angles.
We discovered that crossing Arabidopsis thaliana plants of different ploidies, so that seeds receive an excess of paternally or maternally contributed chromosomes, has a dramatic effect on seed growth, with paternal excess increasing seed size and maternal excess inhibiting growth. This is associated with alterations to the cell cycle in endosperm, a nutritive tissue that supports embryogenesis and seed germination. We have established that the effects of paternal and maternal excess are due to genomic imprinting, a system of gene regulation that allows expression of only the paternally or maternally contributed allele of a gene. We are currently analysing genes with altered expression patterns in seeds from interploidy crosses to discover novel imprinted genes, as well as target genes responsible for increased or inhibited seed growth. Many plants, including agronomically important species, exhibit post-zygotic barriers to hybridization, in both interploidy crosses within species and interspecific crosses between related species. These barriers prevent production of potentially valuable new hybrids, but also provide opportunities to manipulate seed size and potentially seed yield. Arabidopsis thaliana exhibits variation in the severity of hybridization barriers, depending on the level of parental genomic imbalance. One accession, Columbia, shows variation in tolerance to maternal or paternal excess (Dilkes et al PlosB, 2008). 4x X 2x crosses produce viable seed, whereas 2x X 4x crosses are lethal. Crossing Col4x pollen to a transparent testa glabra2 (ttg2) seed parent dramatically reduces lethality, by forcing endosperm cellularisation. Analysis of further mutants of the flavonoid biosynthesis pathway (FBP) revealed that the rescue mechanism involves communication between the maternal tissues of the seed coat and the zygotically-derived endosperm. The present hypothesis under investigation in the lab is that a maternal messenger that regulates the timing of endosperm cellularisation is blocked or attenuated by a functional FBP; hence loss of the pathway by mutation promotes cellularisation by removing the signaling block.
There is also considerable variation among Arabidopsis accessions to resist the killing effect of Col4x pollen, with some seed parents producing almost no seed abortion. Our aim is to identify the gene(s) responsible for this behaviour, as well as the paternal genes that produce the killing effect. We hope these genes might be harnessed for crop improvement.
Novel plant glycoside hydrolases for bioethanol production
Successful plant reproduction is essential for food production, both in agriculture and in nature. The stationary lifestyle of plants means that mobile pollen is vital for fertilisation. Since plant cells are usually firmly fused together in tissues, pollen production requires radical modification of normal cell division.
Early in pollen development, following meiosis, tetrads of young pollen grains (microspores) are separated by a thick callose wall and each tetrad is surrounded by an outer primary cellulose wall. The callosic ‘barrier’ separates the walls of adjacent microspores, allowing them to develop individually. In order for pollen development to proceed, the tetrad walls must be dissolved to release the microspores. Despite the availability of the Arabidopsis genome sequence, and gametophyte development being well studied, this essential stage in pollen development is poorly understood. The immediate of this project is to identify the genes encoding the enzymes responsible for degrading the tetrad walls. The longer-term aim is to evaluate these enzymes for use in the creation of auto-digesting transgenic plants for bioethanol production.
Tiwari, S., Spielman, M., Schulz, R., Oakey, R. J., Kelsey, G., Salazar, A., Zhang, K., Pennell, R. and Scott, R. J., 2010. Transcriptional profiles underlying parent-of-origin effects in seeds of Arabidopsis thaliana. BMC Plant Biology, 10, 72.
Fenby, N., Pu, H., Pennell, R., Praekelt, U., Day, R. and Scott, R. J., 2010. An uncoupling screen for autonomous embryo mutants in Arabidopsis thaliana. Sexual Plant Reproduction, 23 (4), pp. 255-264.
Taskin, K. M., Turgut, K. and Scott, R., 2009. Apomeiotic pollen mother cell development in the apomictic Boechera species. Biologia Plantarum, 53 (3), pp. 468-474.
Taskin, K. M., Turgut, K. and Scott, R. J., 2009. Somatic embryogenesis in apomict Boechera holboellii. Acta Biologica Hungarica, 60 (3), pp. 301-307.
Cheung, F., Trick, M., Drou, N., Lim, Y. P., Park, J. Y., Kwon, S. J., Kim, J. A., Scott, R., Pires, J. C., Paterson, A. H., Town, C. and Bancroft, I., 2009. Comparative Analysis between Homoeologous Genome Segments of Brassica napus and Its Progenitor Species Reveals Extensive Sequence-Level Divergence. Plant Cell, 21 (7), pp. 1912-1928.
Scott, R. J., Armstrong, S. J., Doughty, J. and Spielman, M., 2008. Double fertilization in Arabidopsis thaliana involves a polyspermy block on the egg but not the central cell. Molecular Plant, 1 (4), pp. 611-619.
Tiwari, S., Schulz, R., Ikeda, Y., Dytham, L., Bravo, J., Mathers, L., Spielman, M., Guzman, P., Oakey, R. J., Kinoshita, T. and Scott, R. J., 2008. MATERNALLY EXPRESSED PAB C-TERMINAL, a novel imprinted gene in Arabidopsis, encodes the conserved C-terminal domain of polyadenylate binding proteins. Plant Cell, 20 (9), pp. 2387-2398.
Spielman, M. and Scott, R. J., 2008. Polyspermy barriers in plants: from preventing to promoting fertilization. Sexual Plant Reproduction, 21 (1), pp. 53-65.
Dilkes, B. P., Spielman, M., Weizbauer, R., Watson, B., Burkart-Waco, D., Scott, R. J. and Comai, L., 2008. The Maternally Expressed WRKY Transcription Factor TTG2 Controls Lethality in Interploidy Crosses of Arabidopsis. PLoS Biology, 6 (12), e308.
Hughes, R., Spielman, M., Schruff, M. C., Larson, T. R., Graham, I. A. and Scott, R. J., 2008. Yield assessment of integument-led seed growth following targeted repair of AUXIN RESPONSE FACTOR 2. Plant Biotechnology Journal, 6 (8), pp. 758-769.