Dr. Manny Delhaize
Principal Research Scientist
Institutional Address: GPO Box 1600,
CSIRO Plant Industry,
Canberra ACT 2601
Personal Website Address:
Email: manny.delhaize@csiro.au
Aspects of mineral nutrition related to (i) plant tolerances to acid soils and (ii) phosphorus efficiency
The Big Question:
The molecular mechanisms related to aluminium and manganese tolerances of plants
The main focus of research is to understand the molecular basis of plant tolerance to acid soils and to identify genes for phosphorus (P) efficiency. Work on acid soils has involved understanding the physiology of tolerance mechanisms to the two main factors that limit plant growth on acid soils, namely aluminium (Al) and manganese (Mn). Our earlier work provided evidence for an Al tolerance mechanism based on the Al-activated efflux of malate from wheat roots (Delhaize et al. 1993). We collaborated with Steve Tyerman's lab in Adelaide to show that the efflux was mediated by an Al-activated anion channel that is permeable to malate (Ryan et al. 1997). Recently, in collaboration with Professor Matsumoto's lab in Okayama University , we have characterized a gene from wheat that encodes this Al-activated transporter of malate and have compelling evidence that it encodes Al tolerance in wheat (Sasaki et al. 2004). Further work on this topic is aimed at establishing the value of the gene to agriculture through its use as a molecular marker and by transgenic approaches. Although Al is generally the most important toxin that limits production on acid soils, Mn toxicity is also widespread on these same types of soils. To isolate genes for Mn tolerance we have used yeast as a means to clone plant genes that confer Mn tolerance. These genes encode membrane proteins localized to the tonoplast and our current hypothesis is that they are transporters involved in sequestering Mn to the vacuole (Delhaize et al. 2003).
Work on P nutrition has involved characterization of Arabidopsis mutants (Dong et al. 1998), phosphate transporter genes (Smith et al. 1997) and promoter analysis of P-responsive genes in barley. The work on barley promoters was primarily undertaken by Petra Schunmann and she has produced elegant work that characterizes the promoter activity in transgenic plants with reporter genes ( Schünmann et al 2004). In addition her recent work has provided the first direct functional evidence for the role of a P-responsive element in the promoters of phosphate transporter genes of barley. The current focus in the P-nutrition work is on the use of microarrays to identify P-efficiency genes in cereals and screening cereal germplasm for P-efficiency with the view identifying molecular markers for this trait.
The Short-term goals:
ditto
| Group (lab) Members and areas of research:
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- Dianne Hebb (technician), Petra Schunmann (Research Scientist)
- Work with the Peter Ryan and Alan Richardson labs based at PI.
Current:
- Graingene2 (P-efficiency and Al tolerance)
Applications submitted or planned:
| Techniques in the Laboratory
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Currently active:
Molecular biology (eg generating transgenics of Arabidopsis, barley, tobacco etc) , physiology related to mineral nutrition, transport studies, yeast as a model system.
In development
Top three areas of knowledge:
- molecular basis of metal tolerances,
- metal transport,
- phosphorus efficiency
Top three technical skills :
- physiology,
- molecular biology,
- transport studies
| Publications - Last 5 Years
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PHD Schünmann, AE Richardson, FW Smith and E Delhaize ( 2004) Characterisation of promoter sequences derived from the Pht1 phosphate transporter genes of barely ( Hordeum vulgare L.). Journal of Experimental Botany (in press)
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T Sasaki, Y Yamamoto, B Ezaki, M Katsuhara, S J Ahn, P R Ryan, E Delhaize , and H Matsumoto (2004) A wheat gene encoding an aluminium-activated malate transporter. Plant Journal (in press)
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Delhaize E , Kataoka T, Hebb DM, and Ryan PR (2003) Genes encoding proteins of the cation diffusion facilitator family that confer manganese tolerance. Plant Cell 15: 1131-1142.
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Ryan PR , Dong B, Watt M, Kataoka T and Delhaize E (2003) Strategies to isolate transporters that facilitate organic acid efflux from plant roots. Plant and Soil . 248: 61-69.
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Delhaize E , Ryan PR, Hocking PJ, and Richardson AE (2003) Effects of altered citrate synthase and isocitrate dehydrogenase expression on internal citrate concentrations of tobacco ( Nicotiana tabacum L.). Plant Soil 248: 137-144.
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Kataoka T, Steklenburg A, Nakanishi, TM, Delhaize E , Ryan PR (2002) Several lanthanides activate malate efflux from roots of aluminum-tolerant wheat. Plant Cell Environ. 25: 453-460.
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Delhaize, E , Hebb, DM, and Ryan PR (2001) Expression of a Pseudomonas aeruginosa citrate synthase gene in tobacco is not associated with either enhanced citrate accumulation or efflux. Plant Physiol. 125: 2059-2067.
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Ryan PR, Delhaize E , Jones D (2001) Function and mechanism of organic acid exudation from roots. Annu. Rev. Plant Physiol. Mol. Biol. 52: 527-560.
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Ma JF, Ryan PR, Delhaize E (2001) The complexing role of organic acids in aluminum tolerance. Trends in Plant Sciences 6: 273-278.
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Delhaize E (2001) The role of root exudates in aluminium tolerance in New Concepts of Plant Nutrient Acquisition. Eds N Ae and K Okada., Springer-Verlag, Tokyo pp 140-155
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Dong B, Ryan P, Rengel Z, and Delhaize E (1999) Phosphate uptake in Arabidopsis thaliana : dependence of uptake on the expression of transporter genes and internal phosphate concentrations. Plant Cell and Environment. 22: 1455-1461
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Delhaize, E. , Hebb, D.M., Richards, K.D., Lin, J-M., Ryan, P.R., Gardner (1999) Cloning and expression of a wheat ( Triticum aestivum L.) phosphatidylserine synthase cDNA. Overexpression in plants alters the composition of phospholipids. J Biol Chem. 274: 7082-7088
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