Uncovering the mechanisms of the root gravitropic set-point angle and its application in agriculture
Lead Research Organisation:
James Hutton Institute
Department Name: Ecological Sciences
Abstract
Root system architecture determines the ability of plants to take up water and nutrients from the soil. The gravitropic set-point angle (GSA) describes the orientation of single roots to the gravitropic vector and is therefore essential for shaping the root system architecture. The GSA differs between root types and even between roots of the same type and can be adapted according to environmental conditions. However, to date it is still largely unknown which signalling pathways maintain the GSA and how the environmental cues are transduced to changes in the angle. Here we propose to use RNA sequencing of barley seminal roots with different GSAs to understand the transcriptomic basis of GSA maintenance. We will then compare the data set to existing transcriptome datasets of the hypergravitropic barley mutant enhanced gravitropism2 (egt2) and of barley roots after rotation to identify candidate genes. These candidate genes we will analyse regarding their expression and mutant phenotype. In parallel, we will dissect the signalling pathway of EGT2 in more detail, by analysing the expression pattern and screening for interaction partners. To understand the influence of the root growth angle in water and nutrient uptake, we will use the egt2 mutant as well as mutants derived from the transcriptome data set, to test plant performance under different challenging soil conditions, such as drought or phosphate starvation. With this proposed project, we hope to gain new insights into GSA signalling and a better understanding for the connection of the root growth angle to different soil conditions.
Publications
Kirschner G
(2024)
Genetic regulation of the root angle in cereals
in Trends in Plant Science
| Description | The goal of the award is to develop a better understanding of root angle regulation in barley. WP1 aimed to analyse transcriptomics underlying root angle maintenance in barley seminal roots. For this, tissue was successfully collected of roots with different angles for RNA sequencing, separating the root sample into tissues (root cap, meristem, and elongation zone) that are important for the gravity response using laser-capture dissection microscopy (M 1.1, D 1.1). Transcripts that are correlated with the root angle have been identified, which will build the basis for analysing the role of the genes in root angle maintenance in the second part of the award. The second objective (WP2) was to analyse the signalling network of the root angle key gene ENHANCED GRAVITROPISM2 (EGT2). For that, protein interactors were analysed and this identified a gene putatively related to heavy metal transport as an interesting candidate based on the root angle of its haplotypes (M 2.2, D2.2). In the second part of the award, its expression pattern will be analysed in detail and a mutant will be isolated from a barley mutant collection available in-house in collaboration with Kelly Houston (and with the help of additional funding from SSCR - Scottish Society for Crop Research). In parallel, a reporter construct for the expression of EGT2 under the endogenous promoter and fused to the coding sequence of GFP was cloned, and successfully transformed into barley (D2.2). In the second part of the fellowship, the expression pattern of EGT2 will be analysed in the transgenic plants. Previously we found that in egt2 mutants, genes related to the cell wall were differentially expressed. Therefore, a new collaboration was started with Dr. Timo Engelsdorf at the University of Marburg, Germany (with the help of additional travel funding from EMBO) to analyse the cell wall composition of the egt2 mutants. It was found that the composition is similar to wild type in regard to the amount of sugars, but that the cell wall acetylation is increased in the mutants. In addition, in collaboration with Dr. Kenneth Loades at the home institute, we analysed root mechanical properties of the egt2 mutant, and found that egt2 mutants have a higher tensile strength than the wildtype. These findings imply that EGT2 regulates cell wall properties and thereby root mechanical properties. Going forward, it will be interesting to analyse if the change in cell wall properties and root stiffness is causing the hypergravitropic root phenotype, and how it affects the roots' ability to penetrate soil. The third objective (WP3) was to analyse the performance of plants with contrasting root angles in different soil conditions. The preliminary results have shown that the egt2 mutant does not perform better than wild type under the drought conditions applied in rhizotrons, even though it has steeper root growth than wild type (D3.1). This suggests that under the given conditions, more roots in deeper soil layers do not provide any advantage to a shallower root system. |
| Exploitation Route | The academic sector will benefit from the fundamental knowledge of genetic networks governing root angle. The candidate genes discovered in the transcriptomic study potentially regulate root angle in barley and these can be used as a basis for further studies in how gene regulatory networks and phytohormones govern the root angle. This knowledge can likely be transferred to other cereal crops like wheat and maize. Mutants of the candidate genes are predicted to have altered root angles, therefore, they can be used in studies comparing the performance of plants with different root angles in different soil conditions (drought, localised phosphate application, low nitrate). The commercial sector will benefit from the knowledge gained about signaling components of the root angle which can long-term facilitate the creation and breeding of crop plants with adapted root system architecture (by genetic modification of specific genes or classical breeding approaches and marker led selection), while analysing the effect on root system architecture under different abiotic stresses will enable designing of the root system architecture accordingly. Crops with root systems adapted to the environmental conditions are likely to be more resilient to climate change induced stress and variation. Hence, plant breeders, farmers and ultimately the consumer will benefit from the knowledge generated by this project. Plant breeders can select more easily for loci that regulate the root angle and thereby adapt the root system to the given environmental conditions, reducing the breeding costs and time for mapping QTLs. |
| Sectors | Agriculture Food and Drink Environment |
| URL | https://www.youtube.com/watch?v=pSntlzbIdBA&list=PLovu47P32cca5_SxX0bRwEPVd0-j3rRI4&index=14 |
| Description | This projects studies on the root mechanical properties in hypergravitropic barley mutants have opened a new field of research. Going forward, root mechanical properties can be included in studies comparing root growth in different soil types, for example in soil from non-tillage and tillage conditions. Roots that have different tensile strengths are anticipated to penetrate soil in different manners, as they are more or less flexible to grow around obstacles or through pores. This can be used to better adapt crop plant root systems to agricultural practices or extreme environments. Societal impacts have also been achieved through involvement in the IBH seminar series, the seminar series "Development presents" and participation in "I'm a Scientist - get me out of here" chats with school classes. |
| First Year Of Impact | 2024 |
| Sector | Agriculture, Food and Drink,Environment |
| Impact Types | Societal |
| Description | Cell wall properties of the hypergravitropic mutant enhanced gravitropism2 |
| Amount | € 1,373 (EUR) |
| Funding ID | 10949 |
| Organisation | European Molecular Biology Organisation |
| Sector | Charity/Non Profit |
| Country | Germany |
| Start | 06/2024 |
| End | 07/2024 |
| Title | Transcriptome of barley roots with different angle |
| Description | Transcriptome of barley cv. Morex root tips (root cap, meristem, elongation zone) of vertically growing roots (90°), more shallowly (80°) and very shallowly (70°) growing roots |
| Type Of Material | Database/Collection of data |
| Year Produced | 2024 |
| Provided To Others? | No |
| Impact | This dataset will be used to select candidate genes whose transcript expression is correlated with the root angle. |
| Description | Collaboration on cell wall analysis |
| Organisation | Philipp University of Marburg |
| Country | Germany |
| Sector | Academic/University |
| PI Contribution | I provided the material of a wildtype and a mutant barley line for cell wall analysis of the roots. |
| Collaborator Contribution | Cell wall analysis by GC-MS at the lab in Marburg. |
| Impact | EMBO travel fellowship for Gwendolyn Kirschner to travel to Marburg Dataset of cell wall composition of egt2 mutant in barley |
| Start Year | 2024 |
| Description | Collaboration on writing a review about the relation of the root angle to nutrient uptake |
| Organisation | University of Copenhagen |
| Country | Denmark |
| Sector | Academic/University |
| PI Contribution | Together, we came up with a concept for a review about how the root angle of cereal crops influences nutrient uptake. |
| Collaborator Contribution | Together, we came up with a concept for a review about how the root angle of cereal crops influences nutrient uptake. |
| Impact | Manuscript draft for review |
| Start Year | 2024 |
| Description | Connecting school students with science outside the classroom |
| Form Of Engagement Activity | Participation in an activity, workshop or similar |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Schools |
| Results and Impact | "I'm a Scientist, Get me out of here", connect school students with science outside the classroom, and help them discover STEM career by text-only live chats |
| Year(s) Of Engagement Activity | 2024 |
| URL | https://imascientist.org.uk/ |
| Description | Crop Innovation Centre Opening |
| Form Of Engagement Activity | Participation in an open day or visit at my research institution |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Policymakers/politicians |
| Results and Impact | Poster presentation, involvement in tours and lunch time discussions at the opening of the Crop Innovation Centre, Invergowrie. |
| Year(s) Of Engagement Activity | 2024 |
| Description | EPSO monthly seminar |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Other audiences |
| Results and Impact | Europe-wide seminar series supported by the European Plant Science Organisation (EPSO) and aimed at the Plant Science community and its stakeholders. |
| Year(s) Of Engagement Activity | 2023 |
| URL | https://epsoweb.org/epso/register-for-the-27th-epso-plant-science-seminar-on-16th-november-2023-the-... |
| Description | University visit - scientific presentation in Nottingham University |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Other audiences |
| Results and Impact | Scientific presentation about my research project, invited by Dr. Rahul Bohsale at the University of Nottingham. Audience were around 40 students and researchers of the Plant Science at Nottingham University. |
| Year(s) Of Engagement Activity | 2024 |