Dr Brent Kaiser
Lecturer B
Wine and Horticulture
The University of Adelaide

Personal Website Address: ???
Email: brent.kaiser@adelaide.edu.au

Research Aims

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The Big Question

My research group focuses on identifying new genetic means to achieve sustainable growing practices for economically important food crops. A major component of this research program is in sustainable nitrogen fertilisation in crop plants where we are dissecting the mechanics of nitrogen uptake and assimilation through reverse genetics and whole genome approaches. Through this research, we hope to achieve our ultimate goal in reducing the reliance on nitrogen fertiliser inputs in economically important crops while maintaining and improving existing yields and quality. I also examine the roles of other transport systems involved in nutrient (ie Nitrogen, Iron, Molybdenum, and Malate) exchange across both biotrophic membrane systems in legume nodules and the root plasma membrane in in the model plant system Arabidopsis thaliana , Soybean, Rice and Grapevines.

Short-term goals

1. Generate and characterise individual plant lines devoid of the ammonium uptake system AMT. These experiments are aimed at identifying in planta function of individual genes in multi-gene families through single and multiple loss-of function studies.
2. Clone the gene responsible for molybdenum transport in plants
3. Identify the in planta function of the putative ammonium transport/sensing protein family SAT1

The research conducted in my lab focuses primarily around nutrient transport in plants and in particular how nitrogen and trace element nutrient transport proteins function and are regulated at the genetic level. We utilise the model plant system Arabidopsis thaliana and economically important crops including grapevines and soybean. The mains goals of the research are to identify important control genes in plant nutrient transport, identify their location and function in planta and their contribution to nutrient transport (uptake or internal mobilisation) in plants.

We operate a fully functional PC2 level molecular and protein analytical laboratory. Techniques currently used in this research and conducted in the laboratory include recombinant DNA/RNA technology, Northern and Southern blot analysis, PCR and real-time PCR, microarray/macroarray gene expression analysis, cDNA synthesis and cDNA library screening, in situ gene expression, 1D protein analysis, protein purification, Western blot analysis of proteins, antibody based intercellular localisation of expressed proteins and nutrient transport studies on whole plants, yeast and Xenopus oocytes. The laboratory is also an integral part of the new Joint Facility for Genome Analysis which includes specialised equipment for colony picking, macroarraying of lage gene data sets, sensitive gel and blot image collection and reconfigurable computing for advanced bioinformatic analysis. The group also operates environmentally controlled greenhouses and a PC2 certified walk-in growth chamber

Group (laboratory) members and Areas of Research

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• Dr. Sunita Ramesh (Research Associate). Characteristation of the high affinity ammonium transporter family AMT, Molecular regulation of trace element transport in plants

• Dr. Jennifer Guerin (Research Associate). Almond transformation for self-fertility and virus resistance.

• Kate Gridley (PhD candidate). Molecular regulation of molybdenum transport in plants

• Patrick Loughlin (PhD candidate). Role of the ammonium transport/sensing protein family SAT1

• Megan Shelden (PhD candidate, Co-supervised with Prof. Stephen Tyerman). A novel plant based sensor to monitor vine water stress

• Rebecca Dunstan (PhD candidate, Co-supervised with Prof. Stephen Tyerman). Water transport in roots of grapevines during the wetting and drying cycles of Partial root-zone drying.

• Katharine Malone (PhD Candidate, Co-supervised with Prof. Margaret Sedgeley). Role of the self-fertile Rnase gene, SF, in almond.

• Davina Gregory (PhD Candidate, Co-supervised with Prof. Margaret Sedgeley). Generation of molecular markers in Almond

• Scott Carter (Honours Student). Characterisation of the high affinity ammonium transporter AtAMT1;2

• Joanne Ngaire Brady (Honours student). Role of nitrate on grapevine growth and relationship with the molybdenum deficiency response in cv. Merlot.

Funding

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Current

ARC Discovery grants:

• Improving nitrogen use efficiency in crop plants: The role of the high-affinity ammonium transport family AMT, ARC Discovery $225,000 (CI¹s B.N. Kaiser and A.D Glass, 2004-2006)

• Joint Facility for Plant Genome Analysis. ARC Linkage Infrastructure Equipment Fund, $310,000 (CI¹s B. N. Kaiser, P. Langridge, D. Kearney , P. Hoj and S.D. Tyerman, 2004)

• Self fertility in almond: ARC Linkage, $210,000 (CI¹s M. Sedgely and B. N. Kaiser 2004-2006)

• Molecular analysis of the symbiotic interface of N2-fixing legumes, ARC Discovery $450,000 (CI¹s D.A. Day, M. Ludwig, B. N. Kaiser and S.D. Tyerman 2004-2006)

Top Three

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areas of knowledge

1. Legume nitrogen fixation
2. Plant mineral nutrition
3. Molecular genetics

technical skills

1. RNA expression analysis
2. cDNA synthesis and macroarray analysis
3. whole plant nutrient transport studies using radionucleotides

A statement on most significant contributions to this research field

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My research career has primarily focussed on identifying ways to improve plant growth through improvements in mineral nutrition. This Research program is multi-disciplinary that incorporates the techniques of molecular biology, protein biochemistry and whole plant physiology to elucidate nutrient related physiological responses in plants.

Research contributions to the field of plant mineral nutrition can be broken

Down into the various stages of my career. With my MSc at the University of Guelph (1992-1994), I was able to demonstrate that reducing nitrate reductase activity in pea (using a nitrate reductase mutant) circumvented the nitrate-induced reduction in symbiotic N2-fixation (Kaiser et al., 1994, 1997). During my PhD (1995-1999) at the Australian National University , I examined the molecular regulation of ammonium transport across the symbiosome membrane in N2-fixing soybean nodules resulting in the identification of GmSAT1, a symbiosome membrane protein putatively linked to the activity of the high-affinity ammonium transporter family AMT (Kaiser et al., 1998). This research project also expanded into cloning other members of the AMT family in soybean nodules (GmAMT1-3) and a ferrous iron transporter GmDmt1;1 (Kaiser et al., 2003) located on the symbiosome membrane. I began my postdoctoral career (1999) with a four-month visit to the laboratory of Prof. Alain Puppo at the University of Nice France , where I continued my Research into ferrous iron transport across the PBM. While in France, I was awarded a Canadian international postdoctoral fellowship (NSERC) which allowed me to travel to the University of British Columbia to work with Prof. Anthony Glass (International Nutriome Network member and present ARC Discovery grant collaborator) to investigate the role of the

Arabidopsis high-affinity ammonium transporter AtAMT1;1. Using Reverse genetics, I was able to characterise the first in planta measurements of AtAMT1;1 activity using real-time 13N-ammonium radiotracer analysis. Competitive RT-PCR was also used to measure compensatory gene expression patterns of other members of the AMT multi-gene family (Kaiser et al., 2002). On return to Australia (mid 2001), I worked as a GRDC postdoctoral fellow under the supervision of Dr. Josette Masle at the Research School of Biological Sciences at the Australian National University . This project investigated the genetic response in wheat roots and shoots to mechanical impedances such as soil compaction and or drought. Using functional genomic techniques, we identified a number of novel genes derepressed in wheat roots upon mechanical impedance (Kaiser and Masle, unpublished results). Currently, my present position as lecturer in the School of Agriculture and Wine at the University of Adelaide (2003-) is gaining momentum from a research perspective where I have recently been awarded research funds through the ARC to continue working on the high-affinity ammonium transport family AMT and the mechanisms of nutrient exchange across the peribacteroid membrane of N2-fixing legume nodules. I have also engaged in a new project on self-incompatibility in Almond by way of a new ARC funded Linkage grant shared between Prof. Margaret Sedgely and myself.

Research record relative to opportunities

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My research career has primarily focussed on the mechanisms controlling plant mineral transport. This interest has led me into a number of different research topics including transport (ammonium and iron) across the symbiosome membrane in N2-fixing legume root nodules and ammonium transport into root epidermal cells. As a postdoctoral fellow, I relocated with my family to three research groups in Nice France, Vancouver Canada and back to Canberra . This postdoctoral travel has

greatly broadened my research scope and provided the overseas experience to enhance my present research career. Unfortunately, consequences of changing labs and projects can have a negative impact on research production, however I feel I have maintained a respectable level of research output since my PhD in light of the changes I have had to make.

Work I completed in my postdoctoral position in Vancouver and Nice has been published (Kaiser et al., 2002, Plant Physiology 130, Kaiser et al., 2003, The Plant Journal 35). Currently, I have just finished the first year of tenurable lectureship at the University of Adelaide in the School of Agriculture and Wine. Since beginning in Adelaide , my personal research output has been reduced due to time constraints in setting-up a new research laboratory, writing and delivering lectures in Viticultural science and applying for external research money through the ARC. Luckily, success in the 2003 ARC rounds resulted in obtaining 2 Discovery grants, 1 linkage and 1 linkage infrastructure grant.

With research funding in place, I have begun increasing my research group to include at present 2 ARC funded research associates, 6 PhD students, and 2 Honours students. All members of the research group are active in the lab and therefore I expect the group's research output to increase accordingly in 2004 and subsequent years.

Other evidence of impact and contributions to the field

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During my research career I have been active in plant science Research and have contributed to the field by publishing 10 referred journal articles. I have also presented 5 oral talks and 8 posters at international conferences. I have co-chaired a symposium on Plant Root Mineral transport at CoMBio 2002. Research awards which I have received include a Canadian NSERC International Postdoctoral Fellowship and the Best Student Oral Presentation at CoMBio 1998.

I am a member of the Australian Society of Plant Scientists and the American Society

of Plant Biologists.

I have been asked to be a reviewer for Plant Physiology, Journal of Experimental Botany and Journal of Plant Physiology, Theoretical and Applied Genetics, and Planta

Publications

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• Kaiser, B.N ., Moreau, S., Castelli, J. Thomson, R.M., Lambert, A., Bogliolo, S., Puppo, A. and Day. D.A. (2003) The soybean Nramp homologue, GmDMT1, is a symbiotic divalent metal transporter capable of ferrous iron transport . The Plant Journal 35, 3 295-304.

• Kaiser, B.N., Rawat, S.R., Siddiqi, M.Y., Masle, J., and Glass A.D.M. (2002) Functional analysis of an Arabidopsis T-DNA "knockout" of the high-affinity NH4+ transporter AtAMT1;1 . Plant Physiology 130, 1263-1275.

• Moreau, S., Thomson, R.M., Kaiser, B.N., Trevaskis, B., Guerinot, M.L., Udvardi, M.K., Puppo, A., and Day. D.A. (2002) GmZIP1 encodes a symbiosis specific zinc transporter in soybean. Journal of Biological Chemistry 277, 4738-4746.

• Glass, A.D.M., Britto, D.T., Kaiser, B.N ., Kinghorn, J.R., Kronzucker, H.J., Kumar, A., Okamoto, M., Rawat, S., Siddiqi, M.Y., Unkles, S.E., and Vidmar, J. (2002) The regulation of nitrate and ammonium transport systems in plants. Journal of Experimental Botany 53, 1-10.

• Day, D.A., Kaiser, B. N., Thomson, R., Udvardi, M.K., Moreau, S. and Puppo, A. (2001) Nutrient transport across symbiotic membranes from legume nodules. Australian Journal Of Plant Physiology 28, 667-674.

• Glass, A.D.M., Brito, D.T., Kaiser, B.N ., Kronzucker, H.J., Kumar, A., Okamato, M., Rawat, S.R., Siddiqi, Y., Salim, S.M., Vidmar, J., and Zhuo, D. (2001) Nitrogen transport in plants, with an emphasis on the regulation of fluxes to match plant demand. J. Plant Nutr. Soil Sci 164, 199-207.

• Kaiser, B.N ., Finnegan, P.M., Tyerman , S.D. , Whitehead, L.F., Bergersen, F.J., Day, D.A. and Udvardi, M.K. (1998) Characterisation of an ammonium transport protein from the peribacteroid membrane of soybean nodules. Science 281, 1202-1206.

• Shelp, B.J., Kaiser, B.N. and Deschene, A.M. (1998) Registration of five near-isogenic Juneau pea lines with altered nodulation and nitrate reductase deficiency. Crop Science 38(2), 554.

• Kaiser, B.N ., Layzell, D.B. and Shelp, B.J. (1997) Role of oxygen limitation and nitrate metabolism in the nitrate inhibition of nitrogen fixation by pea, Physiologia Plantarum 101, 45-50.

• Kaiser, B. N ., Thumfort, P., Layzell, D.B. and Shelp, B.J. (1994) Oxygen limitation of N2 fixation in various legume symbioses, Can. J. Plant. Sci 74, 853-855.