Potential research projects at the ANU Node

 

A number of broad areas are listed (1-5) and potential projects within each area are given (a,b,c,d,e,f etc).

 

1. Characterising plants that are resistant to drought and excess light.

a). We have recently identified the ALX8 gene that confers drought tolerance. It regulates key processes in stress signaling, including elevated levels of the stress hormone, ABA and improved water use efficiency. The aim of the project will be to model how the mutation enhances drought tolerance by using a combination of 3D modeling, in vitro assays and assays in yeast using the wild-type and mutant forms of the gene.
b). We have a number of molecular genetic projects where you could clone and identify novel mutants (genes) involved in drought and oxidative stress tolerance.
(i) Map-based cloning and functional analysis of a light and drought tolerant mutation, alx3. Analyses include transcript profiling, measuring photosynthetic rates, water use efficiency and assaying the levels of reactive oxygen species and antioxidants.
(ii) Cloning on an alx mutant that is involved in heat stress signaling under oxidative stress.
d) Assaying levels of Ca++, IP3, ABA and antioxidants during drought in our drought tolerant plants to study the role of these compounds in drought tolerance
e) Analysis of double mutants in droughts stress tolerance and ABA mutants (abi1, abi2) to define signaling pathways that control stomatal aperture and water use efficiency
f) Creation of transgenic plants in rice and barley with key novel genes we have identified to manipulate drought tolerance in crop plants

 

2. Plant Development and Carotenoid Biosynthesis.

a). We are investigating the role of carotenoids and auxin in mediating apical dominance and chloroplast development. A recently identified novel gene alters the number of branches on a plant and the carotenoid content of the cell. A project will be to use GFP and GUS protein fusions to study the function and subcellular distribution of this gene. Forward and reverse genetic approaches are being utilised to understand the role of this novel gene during plant development.
b). We are also focusing on the transcriptional and post-transcriptional mechanisms that regulate the expression of key carotenoid biosynthetic genes. The promoters of several genes will be characterized in detail using reporter gene technology (e.g. luciferase, GUS, GFP). Bioinformatics approaches will be undertaken to elucidate potential cis-elements involved in promoter function and tested using transient and stable transformation systems developed for Arabidopsis and tobacco.
c). We aim to further investigate the effects of altered carotenoid gene expression on pigment biosynthesis and chloroplast development in Arabidopsis. This project will involve the construction, and testing of chemical inducible binary vectors to achieve over expression and/or gene silencing (RNAi) of carotenoid biosynthetic genes. This approach will allow us to understand transient regulatory events in carotenoid biosynthesis.
d). The regulation of carotenoid biosynthetic genes can be effected by abiotic stimuli (e.g. high light). Microarrays will be performed to understand the effects of high light stress on early signal transduction pathways in Arabidopsis and its impact upon carotenoid biosynthesis.

 

3. Studying the function of novel transcription factors on photoprotection and photosynthetic acclimation to altered light regimes (in collaboration with Murray Badger, RSBS).

a). We have used microarrays to identify a number of genes that are upregulated when plants are placed under environmental stress. A series of transgenic plants with increased expression of the transcription factors has been generated. The project would be to analyse the effect on photosynthetic rates, leaf shape and photoprotection.

 

4. A molecular approach to understanding the role of photorespiration in optimizing photosynthetic energy flow within a leaf.

a).We have developed several knockdown and overexpression lines in Arabidopis thaliana of selected genes in the photorespiratory cycle to understand the rate limiting steps of this pathway under conditions of limited CO2 availability and elevated temperature. This project will use standard molecular biology techniques (PCR, DNA gels), analysis of metabolite pools (metabalomics), as well as leaf gas exchange and chlorophyll fluorescence to identify which key photorespiratory genes are important in regulating the photorespiratory cycle

 

5. Photoprotection: interaction of npq and photoinhibition (joint with Dr Shunichi Takashi, Research School of Biological Sciences (RSBS)

a). It has been well demonstrated that non-photochemical quenching (NPQ) helps to avoid photosystem II (PSII) form photoinhibition. Because excess of absorbed light energy has been assumed to accelerate photodamage to PSII via the acceptor-side photoinhibition, dissipation of the excess of absorbed light energy through NPQ is proposed to suppress the damage process. However, recent our studies have demonstrated that the excess of absorbed light energy does not accelerate the damage to PSII but inhibits the repair of photodamaged PSII. This finding suggests that NPQ and induction of NPQ by cyclic electron flow around PSI might be important to avoid inhibition of the repair of photodamaged PSII caused by excess of absorbed light energy. To examine this hypothesis, we are going to investigate the effect of impairment of NPQ and cyclic electron flow around PSI on the photodamage to PSII and the repair of photodamaged PSII separately using Arabidopsis NPQ and cyclic mutants. Ultimately, we are going to see the effect of impairment of NPQ and cyclic on the synthesis of D1 protein and the level of psbA transcript using radioisotope and qRT-PCR, separately. Experimental equipments and techniques required for this project has been already prepared.

 

For additional information email:

Professor Murray Badger murray.badger@anu.edu.au

Associate Professor Barry Pogson Barry.Pogson@anu.edu.au