Acquiring highly resolved root images of a cereal introgression line with enhanced root growth, and performance under low nitrogen stress by X-ray Computed Tomography
EMSL Project ID
60182
Abstract
The aim of this work is to obtain unambiguous data on the root specific architecture of a wheat introgression line 99 that has greater below ground biomass, and outperforms the cultivated parental under low nitrogen (N) stress. This is important because of the environmental damage caused by agricultural nitrogen use, and cultivars that can use N efficiently by accumulating carbon below-ground as higher root biomass, could help to mitigate the dual threat of environmental degradation and energy consumption from agriculture. The QTL interval in the IL from wild emmer wheat includes two uncharacterized genes predicted to be involved in N-use, both expressed at higher levels in the IL under low-N, and both preferentially expressed in roots. To determine if root specific architecture (RSA) is a key physiological component of the IL response, we wish to accurately assess in situ, the spatial conformation, branch angle, length, and biomass of the IL roots under control and limited N, using non-invasive X-CT imaging. This will provide dynamic information about root response to low N in the IL, which is impossible using destructive analyses. This project exploits recently published parameters for generating root images by X-CT for rice. We anticipate requiring 82h of X-CT usage time to generate high quality scans in 14-, 21-, and 28-day-old plants and completing the project within one month. These scans will be used to determine differences including the number of root tips, root biomass, root length, branching and branch angles caused by genotype and low N environment. Data to be collected at PNNL will include root fresh and dry weight, to calculate specific root length (SRL). The chemical profile of the root growth media and wheat tissue, i.e., N content and primary metabolites, will be collected at our home institution (UC Davis). These data will be combined to calculate N-use efficiency (NUE), Nitrogen uptake efficiency (NUpE), and root exudation, to serve as a benchmark for understanding the underlying mechanism for better performance of the IL.
This project will therefore: 1) refine methods for the visualization of RSA using X-CT for species with small root diameters, and this fundamental information would have broad application beyond this project. 2) Clarify root biomass and RSA of the IL in comparison to the parental line. The IL root network is expected to cover a greater soil area under low N due to amplified lateral and primary root growth. 3) Provide a conceptual understanding of the physiological mechanism underlying the IL root response based on X-RT-derived RSA data, in combination with NUE, SRL, and NUpE.
In the long-term, our work to positionally clone the causal gene(s) should reveal novel mechanisms for N-use and root growth, and pinpoint desirable allelic variants of the gene(s) for deployment across wheat breeding programs. This work could conceivably allow for a more judicious use of nitrogenous fertilizers, thereby lessening the severity of the energy costs, and air and water pollution associated with excess N-fertilizer use for large-scale agriculture.
Project Details
Project type
Exploratory Research
Start Date
2021-12-01
End Date
2022-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members