Thesis: The effect of soil phosphorus status on leaf development in Hakea prostrata in its native habitat
Phosphorus (P) taken up as inorganic phosphate (Pi) is essential for plant metabolism. Pi fertilisers are widely used in farming, but P is a non-renewable resource. Moreover, intensive fertilisation may lead to increasing amounts of Pi in soils which can cause environmental pollution. Therefore, there is a need to produce more P-use efficient crops. New selection strategies for such breeding projects can be enlightened by understanding naturally P-use efficient plants. Hakea prostrata (Proteaceae) naturally grows in low-P conditions in south-western Australia. Several morphological and physiological adaptations to P-limitation have been identified in some south-western Australian Proteaceae, but how these strategies are connected at a molecular level is unclear. One contributing factor to high PUE in Proteaceae is delayed greening. Delayed greening is characterised by the temporal separation of leaf growth from the development of chloroplasts and photosynthetic capacity. The P-rich cytosolic ribosomal RNA necessary for growth is synthesised early and is later partly recycled to allow synthesis of the P-rich plastid ribosomal RNA needed for the development of photosynthetic machinery. Another reason why P is vital for plants is that it is a component of ATP, a universal cellular “energy currency”. ATP is synthesised in mitochondria as an outcome of respiration, a fundamental energy-conserving process. Various mitochondrial and nuclear genes encoding proteins involved in respiration respond to plant P-status. My project also aims to quantify the responsiveness of these genes involved in respiration to plant P-status.
Why my research is important
My research will contribute to finding a solution to the phosphate dichotomy facing our farming systems, as the knowledge gained may benefit future breeding efforts aimed at increasing phosphorus-use efficiency in crops, thereby minimizing the need for expensive phosphate fertilisers. The need to solve this problem will increase as we need to at least maintain, but more likely increase crop yields.