Exploring and synthetically rewiring NSP2 nutrient regulation of arbuscular mycorrhizal symbiosis
Lead Research Organisation:
University of Cambridge
Department Name: Plant Sciences
Abstract
PhD project strategic theme: Bioscience for sustainable agriculture and food
Soil nutrient availability is a major factor that affects plant growth. To avoid nutrient limitation, most plants form a beneficial symbiotic relationship with arbuscular mycorrhizal (AM) fungi that enhances soil nutrient uptake. AM colonisation has long been known to be dependent on soil nutrient conditions, particularly in how it is inhibited by high levels of inorganic phosphate. NODULATION SIGNALLING PATHWAY 2 (NSP2) is a GRAS-domain protein that is a key transcriptional regulator in a separate symbiosis for nodule development and has only recently been shown to be involved in mycorrhization. Furthermore, NSP2 over-expression in barley was found to override the inhibition of AM development in high levels of phosphate. This has promising implications for the potential use of AM fungi to increase crop yields in highly fertilised fields.
This project aims to investigate the regulation of mycorrhization by manipulating nutrient signalling around NSP proteins, with the aim of being able to regulate NSPs in such a way as to maximise AM symbiosis in crops. A bioinformatics approach will be taken to identify key components of nutrient signalling directly upstream and downstream of NSPs. With the regulation network characterised, synthetic constructs will be generated to express NSP2 to different degrees by varying promoter and terminator combinations, in addition to manipulation of NSP2 regulators, such as miR171h. The performance of these synthetic lines with respect to AM colonisation and development will be assessed in search of an optimum level of NSP2 expression that sufficiently overrides the nutrient inhibition of symbiosis, whilst still exhibiting healthy growth and development.
Beyond the control of the level of expression of NSP2, a synthetic biology approach will also enable the nutrient regulation itself to be rewired. Through bioinformatics and promoter analysis, cis elements related to nutrient regulation will be identified. This will enable their removal or replacement with alternative promoters. In this way, NSP2 could either have its nutrient regulation lifted or be placed under a novel regulation system, such as the inverse of the normal nutrient regulation or a synthetically inducible system.
Manipulating the nutrient regulation of NSP2 in these ways will not only elucidate aspects of the regulation network itself, but will also allow for the identification of an optimal expression system of NSPs that will result in plants that are better able to form beneficial symbiotic interactions with AM fungi and thereby uptake phosphates and nitrates more effectively. Such plants would not need as much fertiliser application when grown as crops, and their potential would be very exciting in industrial farming contexts.
Soil nutrient availability is a major factor that affects plant growth. To avoid nutrient limitation, most plants form a beneficial symbiotic relationship with arbuscular mycorrhizal (AM) fungi that enhances soil nutrient uptake. AM colonisation has long been known to be dependent on soil nutrient conditions, particularly in how it is inhibited by high levels of inorganic phosphate. NODULATION SIGNALLING PATHWAY 2 (NSP2) is a GRAS-domain protein that is a key transcriptional regulator in a separate symbiosis for nodule development and has only recently been shown to be involved in mycorrhization. Furthermore, NSP2 over-expression in barley was found to override the inhibition of AM development in high levels of phosphate. This has promising implications for the potential use of AM fungi to increase crop yields in highly fertilised fields.
This project aims to investigate the regulation of mycorrhization by manipulating nutrient signalling around NSP proteins, with the aim of being able to regulate NSPs in such a way as to maximise AM symbiosis in crops. A bioinformatics approach will be taken to identify key components of nutrient signalling directly upstream and downstream of NSPs. With the regulation network characterised, synthetic constructs will be generated to express NSP2 to different degrees by varying promoter and terminator combinations, in addition to manipulation of NSP2 regulators, such as miR171h. The performance of these synthetic lines with respect to AM colonisation and development will be assessed in search of an optimum level of NSP2 expression that sufficiently overrides the nutrient inhibition of symbiosis, whilst still exhibiting healthy growth and development.
Beyond the control of the level of expression of NSP2, a synthetic biology approach will also enable the nutrient regulation itself to be rewired. Through bioinformatics and promoter analysis, cis elements related to nutrient regulation will be identified. This will enable their removal or replacement with alternative promoters. In this way, NSP2 could either have its nutrient regulation lifted or be placed under a novel regulation system, such as the inverse of the normal nutrient regulation or a synthetically inducible system.
Manipulating the nutrient regulation of NSP2 in these ways will not only elucidate aspects of the regulation network itself, but will also allow for the identification of an optimal expression system of NSPs that will result in plants that are better able to form beneficial symbiotic interactions with AM fungi and thereby uptake phosphates and nitrates more effectively. Such plants would not need as much fertiliser application when grown as crops, and their potential would be very exciting in industrial farming contexts.
Organisations
Studentship Projects
| Project Reference | Relationship | Related To | Start | End | Student Name |
|---|---|---|---|---|---|
| BB/M011194/1 | 01/10/2015 | 31/03/2024 | |||
| 2274147 | Studentship | BB/M011194/1 | 01/10/2019 | 31/12/2023 | Darius Zarrabian |