Phosphorus is an essential macronutrient for plant growth and cannot be replaced by any other element. It is the second most limiting nutrient after N. Up to 50% of the worlds agricultural soils are classed as P-deficient especially in SE Asia and sub-Saharan Africa . Plants take up inorganic P as phosphate, but these fertilizers are unsustainable since they are produced from rock phosphate which is a non-renewable resource and their production is energy intensive. In addition they are often too expensive or unavailable to subsistence farmers . Organic fertilisers (e.g manures) are not directly available to the crop and first need to be mineralised by microbial or plant mediated processes. A high proportion of P fertilizer is not taken up by the crop and can leach from soil to cause severe environmental damage. In this context, crops with better P acquisition and P use efficiency have to be identified .
Millets are a group of small seeded cereals grown throughout Africa and Asia. They are highly nutritious, well adapted to drought conditions and a staple of low input dryland agriculture, especially for subsistence farmers. Foxtail millet is a good model for other millets, being a self-pollinated diploid with a small genome and many varieties are available via the Gene Bank at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) . Genome sequence is also available for other millets such as pearl millet  allowing discoveries to be translated from foxtail millet to other millets. Previous work from the primary supervisor’s lab has characterised low P response in foxtail millet and examined the role of P transporters [6,7].
To efficiently acquire P, as well as other nutrients and water, from the soil appropriate root architecture is required. Plants show considerable genetic variation for root traits  and some of this variation is accounted for by activity of auxin dependent and auxin independent transcription factors. The co supervisor is an expert in root architecture and auxin response.
In this project we will compare root phenotypes in hydroponics and soil with different levels of P for 10 foxtail millet genotypes known from studies by our collaborators in India to have differing P efficiency. We will also use the hydroponic system to quantify the level of root associated/secreted phosphatase in these varieties and relate this to P-use efficiency. Finally expression of the key transcription factor PTF1  will be examined in the different genotypes to determine whether this is a useful marker for breeding P efficient plants. During this project there will be an opportunity to spend time with our research collaborators at ICRISAT in Hyderabad (India) who have excellent facilities for genomics and field based research.
Applicants will need to have or be willing to apply for funding to cover fees and maintenance.
 Lynch (2011) Root phenes for enhanced soil exploration and phosphorus acquisition: tools for future crops Plant Physiol. 156, 1041-1049.
 Cordell, D. et al. (2009) The story of phosphorus: Global food security and food for thought. Global Envt. Change 19, 292-305.
 Baker, A., et al (2015) Replace, reuse, recycle: improving the sustainable use of phosphorus by plants J. Exp. Bot. 66, 3523-3540 doi: 10.1093/jxb/erv210
 Upadhyaya et al., (2011) Identification of trait-specific germ plasm and developing a mini core collection for efficient use of foxtail millet genetic resources in crop improvement. Field Crops Research 124, 459-467.
 Varshney et al., (2017) Pearl Millet genome sequence provides a resource to improve agronomic traits in arid environments. Nature Biotechnology 35, 969-976
 Ceasar et al., (2014) Phosphate concentration and arbuscular mycorrhizal colonisation influence the growth, yield and expression of twelve PHT1 family phosphate transporters in foxtail millet (Setaria italica). PLoS ONE 9(9): e108459. doi: 10.1371/journal.pone.0108459
 Ceasar et al. (2017) Functional Characterisation of the PHT1 family transporters of foxtail millet with development of a novel Agrobacterium-mediated transformation procedure. Scientific Reports 7 art no 14064.
 Li et al., (2011) Overexpression of transcription factor ZmPTF1 improves low phosphate tolerance of maize by regulating carbon metabolism and root growth. Planta 2011 233:1129.