biological sciences HONOURs 2014 - The University of Sydney

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PLANT MOLECULAR
BIOLOGY
Research Interests
My laboratory uses molecular biology and cell biology techniques
to study a range of topics including the legume-rhizobia symbiosis,
long distance signaling in plants and plant food allergens.
The Legume-Rhizobia Symbiosis: To produce our food, the crops
we grow need to have enough nitrogen. This nitrogen is usually
supplied as an expensive, chemically synthesised fertilizer.
Legumes are plants that are able to combine with bacteria,
termed rhizobia, to form an association (symbiosis) where
nitrogen from the air is converted to a form that can be used
by plants. This means they can grow without nitrogen fertilizer
and also that they can leave nitrogen in the soil for the next crop
grown, reducing the reliance on fertilizers.
The rhizobia are enclosed by a membrane that the plant
synthesises, inside a new organ on the roots of the plant called
a nodule. We are studying the composition, development and
function of the membrane (the symbiosome membrane) as
it is the interface between them and probably controls how
efficiently nitrogen is fixed.
Dr Penny Smith
Room 239A, Macleay
Building A12
T: (02) 9036 7169
E: penny.smith@sydney.
edu.au
Honours projects
1. Which plant genes are expressed in cells infected by rhizobia? Find out how rhizobia modify
plant gene expression. You would use laser capture micro-dissection to isolate cells infected by
rhizobia, isolate RNA and then use RNAseq to compare the expression with that of non-infected cells.
2. Metal transporters on the symbiosome membrane and their role in symbiotic function.
Investigate how reducing the expression of one symbiosome membrane transporter changes the
expression of the other transporters. Investigate this using RNAi, real-time qPCR, proteomics
and/or metabolomics.
3. The role of nutrient transporters in regulating efficiency of nitrogen fixation. What happens
when you reduce the expression of particular transport proteins on the symbiosome membrane?
Use gene silencing to reduce expression of your candidate transporter and investigate how this
affects the nitrogen fixation.
4. Characterisation of the symbiosome space. The symbiosome space is the region inside
the symbiosome membrane that surrounds the bacteroid membrane. This project is a detailed
proteomic study of the symbiosome space. You would then choose a protein for further molecular
characterisation to determine if it is essential for the symbiosis.
5. Other possible projects: a) Molecular characterisation of symbiosome development.
b) Studying changes in the symbiosome membrane proteome throughout development using
quantitative proteomics.