Dr Martha Ludwig
Lecturer
Schools of Plant Biology and Biomedical and Chemical Sciences, Centre for Microscopy and Microanalysis/Faculties of Natural and Agricultural Sciences and Life and Physical Sciences, University of Western Australia

Personal Website Address:
Email: mludwig@cyllene.uwa.edu.au

Research Aims

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The Big Question

Elucidation of the uptake and translocation pathways of carbon and other nutrients in plants at the cell and molecular levels

Short-Term Goals

Evolution of photosynthesis. Plants require sunlight, water and atmospheric CO2 to carry out photosynthesis, one of the most fundamental processes on earth. Depending on its biochemistry, a plant is described as a C3, a C4 or a Crassulacean Acid Metabolism (CAM) plant. It is widely accepted that C4 and CAM plants have evolved from C3 plants and that this process has occurred multiple times in different families of plants. We are looking at the anatomical and molecular changes that have occurred during the evolution of C4 plants from their C3 ancestors, including changes in the regulatory regions of genes encoding photosynthetic isoforms of carbonic anhydrase. Collaborators: Dr. S. von Caemmerer, Australian National University , Canberra , ACT; Prof. P. Westhoff, Heinrich-Heine-Universitaet, Duesseldorf , Germany

Nutrient and water uptake and utilisation. Nitrogen is an essential nutrient for plants; however, it is often the factor limiting plant growth in many soils. Some plants, such as legumes, form symbiotic relationships with bacteria that convert atmospheric nitrogen into forms of nitrogen that can be used by a plant. In exchange, the plant furnishes the bacteria with carbon-containing compounds. We are examining the structure, location and function of the proteins, and the genes encoding them, that are responsible for nutrient exchange between the bacterial symbionts and their host plant. Collaborators: Prof. D.A. Day, UW; Prof. S.D. Tyerman and Dr. B.N. Kaiser, University of Adelaide

The C4 photosynthetic pathway acts as a CO2 concentrating mechanism with the enzyme carbonic anhydrase (CA) catalysing the first step in the pathway. We are investigating the importance of CA in C4 photosynthesis using transgenic technologies. Collaborator: Dr. S. von Caemmerer, Australian National University

We are also looking that the genes and their products, which are involved in phosphorus and water uptake in native plant systems. Collaborators: Prof. H. Lambers and Dr. P. F. Grierson, UWA

Group (Laboratory) Members

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Ms Sandra Tanz (Postgraduate student)

Ms Gimara Duncan (Postgraduate student)

Dr Abu-Baker Siddique (Postdoctoral Researcher)

Funding

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Current

ARC Discovery Project Grant 2004-2006 "Molecular Analysis of the symbiotic interface of N2-fixing legumes"

UWA Research Grant 2004 "Carbonic anhydrase and C4 photosynthesis"

Applications Submitted or Planned

Slade Foundation (planned) "The effects of high CO2 and temperature on rice pollen biology"'

Techniques in the Laboratory

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Currently active

1. Recombinant DNA technology, PCR, quantitative real-time PCR, RACE, genomic DNA and cDNA library construction and screening genomic walking
2. Protein expression and purification, antibody purification, immunoblot analyses
3. Light and transmission electron microscopy
4. Immunocytochemistry at the light/confocal and electron microscope levels

In development

1. in situ hybridisation, in situ PCR
2. NanoSIMS with stable isotopes to elucidate nutrient and ion uptake and translocation pathways in biological samples (http://www.nano.org.au/nano.html)
3. Chloroplast import

Main Areas of Expertise

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Top three areas of knowledge

1. CO2 concentrating mechanisms, including C4 photosynthesis
2. Chloroplast evolution
3. Plant cell and molecular biology

Top three technical skills

1. Isolation and cloning of genes through PCR and library screening
2. Quantitative real-time PCR
3. Immunocytochemistry for light and electron microscopy

A statement on your most significant contributions to this research field

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I have a substantial background in plant cell and molecular biology, along with significant experience in plant physiology and biochemistry. My major research focus has examined how some photosynthetic organisms concentrate atmospheric CO 2 during photosynthesis and this work has involved a number of techniques that are highly relevant for examining plant nutriomics, such as quantitative real-time PCR, cDNA library screening and transgenic plant technology.

In collaboration with D. Day, S. Tyerman and B. Kaiser I am currently examining the structure and location of the proteins that are responsible for nutrient exchange between the bacterial symbionts and their host plant in rhizobium-legume symbioses. I am also working in collaboration with H. Lambers on the localisation of transporters in cluster roots

My postgraduate and early post-doctoral work was in the field of plant cell biology and I have a very strong background in immunocytochemistry and other techniques of light and electron microscopy. I also bring a theoretical background in symbiotic relationships to this research field, having examined the endosymbiotic origin of chloroplasts as a postgraduate student and, more recently, the physiology of the symbiotic association between dinoflagellates and giant clams.

Other evidence of impact and contributions to the field

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• 1992-1995: ARC Australian Postdoctoral Fellow
• 1996-1998: Genetics and Molecular Biology Discipline Representative of the Australian Society of Plant Scientists
• 2001-2002: Member of the ComBio 2002 Program and Organising Committee
• 2001-2002: Symposium Stream Organiser for ComBio2002
• 2002: Presenter at the Gordon Research Conference entitled "CO 2 Concentrating Mechanisms in Green Plants", Mount Holyoke College, USA
• 2003-present: Whole Plant Discipline Representative of the Australian Society of Plant Scientists
• 2003-present: Editorial Advisory Committee Member for Functional Plant Biology
• Examiner of numerous Honours and four PhD theses
• Reviewer of manuscripts for Protoplasma , Planta , and Functional Plant Biology

Publications - Last 5 Years

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• von Caemmerer, S., Quinn, V., Hancock , N.C. , Price, G.D., Furbank, R.T. & Ludwig, M. (2004) Carbonic anhydrase and C 4 photosynthesis: A transgenic analysis. Plant Cell Environ. In press.

• Leggat, W., Marendy, E.M., Baillie, B., Whitney, S.M., Ludwig, M. , Badger, M.R. & Yellowlees, D. (2002) Dinoflagellate symbioses: strategies and adaptations for the acquisition and fixation of inorganic carbon. Funct. Plant Biol. 29 : 309-322.

• Ludwig, M. , Sültemeyer, D. & Price, G.D. (2000) Isolation of ccmKLMN genes from the marine cyanobacterium, Synechococcus sp. PCC7002 (Cyanophyceae), and evidence that CcmM is essential for carboxysome assembly. J. Phycol. 36 : 1109-1118.

• Finnegan, P.M., Suzuki, S., Ludwig, M. & Burnell, J.N. (1999) Differential expression of four genes encoding phosphoenolpyruvate carboxykinase in the C 4 monocot Urochloa panicoides . Plant Physiol. 120 : 1033-1041.

Ten career-best publications

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1. von Caemmerer, S., Quinn, V., Hancock, N.C., Price, G.D., Furbank, R.T. & Ludwig, M. (2004) Carbonic anhydrase and C 4 photosynthesis: A transgenic analysis. Plant Cell Environ. (in press; accepted 11 Nov 2003).

2. Ludwig, M. , Sültemeyer, D. & Price, G.D. (2000) Isolation of ccmKLMN genes from the marine cyanobacterium, Synechococcus sp. PCC7002 (Cyanophyceae), and evidence that CcmM is essential for carboxysome assembly. J. Phycol. 36 : 1109-1118.

3. Finnegan, P.M., Suzuki, S., Ludwig, M. & Burnell, J.N. (1999) Phospho enol pyruvate carboxykinase in the C 4 monocot Urochloa panicoides is encoded by four differentially expressed genes. Plant Physiol. 120 : 1033-1041.

4. Ludwig, M. , von Caemmerer, S., Price, G.D., Badger, M.R. & Furbank, R.T. (1998) Expression of tobacco carbonic anhydrase in the C 4 dicot Flaveria bidentis leads to increased leakiness of the bundle sheath and a defective CO 2 concentrating mechanism. Plant Physiol. 117 : 1071-1081.

5. Price, G.D., Sültemeyer, D., Klughammer, B., Ludwig, M. & Badger, M.R. (1998) The functioning of the CO 2 concentrating mechanism in several cyanobacterial strains: a review of general physiological characteristics, genes, proteins and recent advances. Can. J. Bot. 76 : 973-1002.

6. Ludwig M. , Lind, J., Miller, E. & Wetherbee, R. (1996) High molecular mass glycoproteins associated with siliceous scales and bristles of Mallomonas splendens (Synurophyceae) may be involved in cell surface development and maintenance. Planta 199 : 219-228.

7. Ludwig, M. & Burnell J.N. (1995) Molecular comparison of carbonic anhydrase from Flaveria species demonstrating different photosynthetic pathways. Plant Mol Biol 29 : 353-365.

8. Ludwig, M. & Gibbs, S.P. (1989) Localization of phycoerythrin at the lumenal surface of the thylakoid membrane in Rhodomonas lens . J. Cell Biol. 108 :875-884.

9. Ludwig, M. & Gibbs, S.P. (1989) Evidence that the nucleomorph of Chlorarachnion reptans (Chlorarachniophyceae) are vestigial nuclei: Morphology, division and DNA-DAPI fluorescence. J. Phycol. 25 :385-394.

10. Ludwig, M. & Gibbs, S.P. (1985) DNA is present in the nucleomorph of cryptomonads: Further evidence that the chloroplast evolved from a eukaryotic endosymbiont. Protoplasma 127 :9-20.