Location: National Clonal Germplasm Repository for Citrus
Project Number: 2036-21000-012-009-R
Project Type: Reimbursable Cooperative Agreement
Start Date: Nov 1, 2023
End Date: Oct 31, 2025
Objective:
The Long-Term Goal of this project is to create strategies that enable the California citrus industry to adapt to climate change. Toward that goal, we hypothesize that utilizing metabolic models will all us to obtain a thorough understanding of the cellular and metabolic processes associated with drought tolerance in citrus – which in turn will allow our team and others to:
(i) design amendments that increase drought tolerance – Near-Term Solution and
(ii) engineer citrus with increased drought tolerance – Long-Term Solution
Approach:
Important Prior Study. A multi-year field experiment determined the levels of drought tolerance in 12 different citrus rootstocks that were grafted to sweet orange (doi:10.1016/j.scienta.2011.03.039).
Proposed Studies. Our study will build on that prior research by using metabolic models to investigate the two rootstocks with the greatest drought tolerance and the rootstock with the least tolerance. Our proposed study has two objectives.
Objective 1 is to construct metabolic models of two different drought tolerant citrus rootstocks – ‘Cravo’ ‘Rangpur’ lime and ‘Sunki’ mandarin.
Methodologies: Activity 1D: To construct high quality metabolic models of 'Cravo’ ‘Rangpur’ lime and ‘Sunki’ mandarin, we will use (i) established protocols that we have optimized and (ii) our previously constructed model of Citrus clementina as the framework. Constructing a metabolic model requires both an annotated genome sequence (Activity 1B), which will be performed by Cantata Bio, and omics datasets (Activity 1C). RNA-Seq datasets will be obtained using the methods optimized by the Borneman lab for citrus (doi: 10.1038/s41540-020-00142-w). Illumina sequencing will be performed at the Genomics Core at UC Riverside. Metabolomics will be performed at the Metabolomics Core Facility at UC Riverside. These state-of-the-art metabolomics analyses will include a thorough set of methods that assess central carbon metabolism, lipidomics, secondary metabolites, neutral sugars, as well as phytohormones. Activity 1A: The plant material used for the genome sequencing (leaves) and omics analyses (leaves and roots) will come from the National Clonal Germplasm Repository for Citrus & Dates at UC Riverside.
Objective 2 is to use these new metabolic models to both (a) obtain a thorough understanding of the drought tolerance mechanisms deployed by these two different rootstocks in comparison to a drought susceptible rootstock and to (b) design near- and long-term strategies that translate these findings into solutions for the growers.
Methodologies: Plant Genotypes (Activity 2A). Two drought-tolerant (‘Cravo’ ‘Rangpur’ lime and ‘Sunki’ mandarin) and one drought susceptible (Carrizo citrange rootstock will be grafted to sweet orange scions (Washington navel) using the t-bud grafting method and plant material from the National Clonal Germplasm Repository for Citrus & Dates at UC Riverside.
