Dr Brent Kaiser

Teaching Interests

Program Coordinator: Bachelor of Viticulture & Oenology, Post Graduate Viticulture

Courses: Viticultural Science A & B, Plant Molecular Biology, Foundations in Plant Science

Research Interests

Nitrogen Transport and Assimilation in Plants

A major stream of this research program is centred around sustainable nitrogen use by crop plants where we are helping to dissect the mechanics of nitrogen uptake, cellular transport and assimilation through reverse and forward genetic approaches and whole genome analysis. Our research goals are ultimately aimed at reducing the levels of nitrogen fertiliser inputs in economically important crops while maintaining and/or improving existing yields and quality. This work encompasses both annual and perennial crops such as maize, wheat, grapevines, and the model plant system Arabidopsis. 

 

Symbiotic Nitrogen Fixation in Legumes

Most legumes can develop a symbiotic association with soil bacteria of the Rhizobium family. This symbiosis is highly important to agriculture and the global nitrogen cycle. With legumes, the symbiosis provides an ecological niche, where plants have access to reduced nitrogen (NH3) which is converted from freely available atmospheric nitrogen (N2) by the symbiotic bacterial enzyme nitrogenase. In return, the plant provides carbon from photosynthesis and essential nutrients to support bacterial growth. 

The plant and bacteria have co-evolved where unique signalling events occur between legume epidermal root cells and specific Rhizobium sp. found naturally in the soil solution. Successful exchange between the symbionts initiates the development of the highly specialised root nodule, which develops from rapidly dividing root cortical cells. Bacteria invade root hairs and migrate to the developing nodule through an invaginated plasma membrane (infection thread). When the infection thread arrives at the developing nodule, it releases the symbiotic bacteria (bacteroids) into the cell cytosol. During release, bacteroids are enclosed in an inside out plasma membrane (the peribacteroid membrane - PBM), which forms the symbiosome structure.

We are interested in the exchange of nutrients between the plant and bacteroid and consider this an important regulatory step that is key to a successful and effective symbiosis. Ultimately our goals through this research is to better understand the transport and ancillary proteins operating on the PBM and to identify limiting processes which can be modified to improve upon the nitrogen fixation process. In this work we primarily use soybean as a model system which is highly valuable seed crop grown by many countries around the globe.

 

Please visit my lab web-page to get information on members of my group, research directions, and student projects.

http://web.me.com/brent.kaiser/BNK_LAB_%282011%29/Kaiser_Lab.html

 

Honours Projects 2012:

1) Functional Evaluation of the Novel Ammonium Channel AMF

Supervisor(s): Brent Kaiser, Steve Tyerman

Brief Project Outline: We have recently identified a novel family of plant and fungal proteins involved in ammonium transport.  This project will characterise the activity of the AMF family in the model plant Arabidopsis thaliana.  This research will involve analysing plants where AMF activity has been genetically altered and examining the activity of Arabidopsis AMF proteins using heterologous systems (yeast and Xenopus laevis oocytes).

In summary, this project will ideally suit an enthusiastic student who is interested in learning more about plant nutrient transport and membrane biology.

Scholarship Available: Yes. Scholarships are competitive and are awarded principally on academic merit. This project will be supported with a top-up scholarship of $2500.00

 

 

2) Symbiotic control of P uptake and its allocation to nitrogen fixing nodules in soybean

Supervisor(s): Brent Kaiser, Sally Smith

Brief Project Outline: This project will investigate the relationship between two symbiotic systems (Rhizobium and Mycorrhiza) on P uptake and its distribution to nitrogen-fixing legume nodules of soybean. Nodule development and activity is positively linked to P availability, however the mechanisms controlling the delivery of P to the nodule are poorly understood.  This project will explore the capacity of the Mycorrhiza symbiosis to deliver P to soybean plants and its effectiveness in delivering P to the nodule.

In summary, this project will ideally suit an enthusiastic student who is interested in learning more about plant microbe interactions, plant nutrient transport and membrane biology.

 

 

Publications

Selected Publications:

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 281:1202-6.

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 35:295-304.

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 130:1263-75.

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 277:4738-46.

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.

Plett, D., Toubia, J., Garnett, T., Tester, M.A., Kaiser, B.N., Baumann, U. 2010. Dichotomy in the NRT gene families of dicots and grass species. PLos ONE Accepted 25/10/2010

Fitzpatrick, K.L, Tyerman, S.D., and Kaiser, B.N. 2008.  Molybdate transport by the plant sulfate transporter SHST1. FEBS Letters 582 (10):1508-13.

Vandeleur, R.K., Mayo, G., Shelden, M.C., Gilliham, M., Kaiser, B.N. and Tyerman, S.D. 2009. The role of PIP aquaporins in water transport through roots: diurnal and drought stress responses reveal different strategies between isohydric and anisohydric cultivars of grapevine Plant Physiology 149:445-460.

Conn, S.J., Gilliham, M., Athman, A., Schreiber, A.W., Baumann, U., Moller, I., Cheng, N., Stancombe, M.A., Hirschi, K.D., Webb, A.A.R, Burton, R., Kaiser, B.N., Tyerman, S.D., Leigh, R.A. Cell-Specific Vacuolar Calcium Storage Mediated by CAX1 Regulates Apoplastic Calcium Concentration, Gas Exchange, and Plant Productivity in Arabidopsis. Plant Cell 10.1105/tpc.109.072769

Kaiser, B.N., Hrmova M. 2010. A Glimpse at Regulation of Nitrogen Homeostasis, Structure doi:10.1016/ j.str.2010.10.003.

DeFalco, T.A., Chiasson, D., Munro, K., Kaiser, B.N., Snedden, W.A. 2010. Biochemical characterization of the soybean calmodulin-binding receptor-like kinase GmCaMK1 and the CaMK family of plants. Febs Letters Accepted 26/10/2010. (IF 3.541, 94/365 Biochemistry & Mol Biology)

Conn, S., Conn, V., Kaiser, B., Tyerman, S.D., Leigh, R.A., Gilliham, M. 2010. Arabidopsis magnesium transporters, MGT2/MRS2-1 and MGT3/MRS2-5, are important for magnesium partitioning within Arabidopsis thaliana mesophyll vacuoles. New Phytologist Accepted 1/11/2010.

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.

Garnett T., Conn V., and Kaiser B.N. (2009) Root based approaches to improving nitrogen use efficiency in plants.  Plant Cell & Environment 32:1272-83

 

 

Professional Interests

Plant Mineral Nutrition

Entry last updated: Saturday, 22 Sep 2012