We have previously tested two contrasting maize inbred lines on their inherent nitrate transport rates and respective responses to growth at low nitrogen supply. The lines were selected from a preliminary investigation into nitrate uptake in maize inbreds by their roots ability to deliver sufficient nitrogen for growth when challenged by low external nitrogen supply (see Garnett, T., et al., Frontiers in Plant Science, 2015). Across a wide range of maize inbreds, we observed significant variation in nitrate transport capacity under these conditions, although the relationship to root architecture and root type (primary, crown and / or seminal) contributing to net nitrate uptake was not investigated. Recently with the investigation by Dechorgnat, J., et al., 2018 (Front Plant Sci, 2018. 9: p. 531) we now know that different root ideotypes display root specific nitrate transport activities. This project will investigate in more detail the regulatory control of root development and nitrogen transport in response to the spatial provision of nitrate or ammonium along a root system.
The outcome of this work will be to profile maize and barley root ideotypes for variation in root architecture and to determine how this relationship influences nitrate and ammonium transport. Underlying genetic signals linked to nutrient dependent root architectural change will be determined using RNA-SEQ transcript analysis. Root architectures will be phenotyped and genetically characterised (RNA transcript evaluation) at varying developmental stages in response to differences in N supply. Orthologous gene sequences to NPF6(x); NRT2(x), NAR2, AMT, AMF and genes linked to downstream signalling intermediates including phytohormones (IAA, ABA, Ethylene), peptide signalling cascades (CLE and CEP) and a range of TFs and miRNAs will be identified by RNA seq data sets and data from online and in-house sequence and microarray databases. Transcriptional signaling cascades will be defined based on differentially expressed genes that coordinate root type development in response to N provision. Gene ontology (GO analysis) will be used to catalogue genes and heatmap analysis used to define target genes to be confirmed by qPCR and in situ PCR techniques.
Additional supervisor for this project is Prof Dabing Zhang (University of Adelaide), Dr Nijat Imin (University of Auckland). This project will be located in Camden Campus (Centre for Carbon Water and Food).
1) Evaluation of root ideotypes for root architecture, root presentation, and root N transport activity
2) Cataloguing contrasting root ideotypes that align root performance to architecture and gene expression
3) Dissection of root signalling pathways that promote root development in response to N cues
HDR Inherent Requirements
In addition to the academic requirements set out in the Science Postgraduate Handbook, you may be required to satisfy a number of inherent requirements to complete this degree. Example of inherent requirement may include:
The opportunity ID for this research opportunity is 2919