Aim

To understand and manipulate the role of aquaporins in CO₂ diffusion inside leaves in order to improve photosynthesis and subsequently plant growth and yields.

Background

Improving photosynthesis can contribute towards greater food security in the coming decades as the world population increases.  A key determinant of photosynthetic efficiency is the availability of CO₂ at the sites of fixation within the chloroplast.  Atmospheric CO₂ enters the leaf through stomata and then has to cross the mesophyll and chloroplast membranes.  These barriers impede CO₂ diffusion resulting in a substantial reduction in concentrations within the chloroplast. 

Aquaporins are channel proteins that facilitate the transport of water and small molecules, including gases, across cell membranes.  Several aquaporins in a number of plants species have been shown to aid CO₂ diffusion and belong to the Plasma membrane Intrinsic Protein (PIP) subfamily of aquaporins.  The broader scope of the project is to functionally characterise PIPs with regards to CO₂ permeability and use this knowledge to improve photosynthesis through increased CO₂ delivery to the chloroplast.

Honours project

Aquaporins are regulated at both the transcriptional and post-transcriptional level.  While we have a good understanding of post-translational protein modifications of aquaporins, there is little understanding of their transcriptional regulation.  The honours project will focus on detailing the transcriptional regulation of the aquaporin PIP members in Arabidopsis and will include (but limited to):

• Characterising the tissue specific expression patterns throughout development using qRT-PCR along with GUS, GFP and/or LUC reporter constructs
• Identify transcription factor binding sites using a combination of phylogenetic shadowing, promoter deletions and site-directed mutations
• Using bioinformatics tools to identify potential PIP regulators; both specific transcription factors and more generally stress conditions that elicit a change in PIP aquaporin expression
• Evaluate reporter construct expression under various stress conditions

The honours candidate will gain experience in general molecular techniques, plant culturing and transformation, in planta visualisation and assessment of reporter gene expression, with aspects of bioinformatics analysis.