Location: Innovative Fruit Production, Improvement, and Protection
Project Number: 8080-21000-033-018-R
Project Type: Reimbursable Cooperative Agreement
Start Date: Sep 15, 2023
End Date: Sep 14, 2027
Objective:
The project is aimed at developing novel citrus hybrids creating using Huanglongbing (HLB) resistant Australian germplasm that will be acceptable to the public, show disease resistance/tolerance traits in HLB endemic areas, and identify hybrids that can be developed as cultivars for future plantings.
Participation by the citrus growers and the industry is an essential part of the project work. ARS will share the information generated and the novel fruits produced by the hybrids with the industry to obtain feedback and improve our strategies for the development and identification of valuable hybrids in the breeding program.
Obj 1. Screen hybrid citrus populations for HLB resistance/tolerance.
Obj 2. Evaluate fruit quality and horticultural traits in the hybrids.
Obj 3. Genetically map HLB resistance traits in segregating hybrid populations.
Obj 4. Assess the mechanisms of resistance/tolerance using single cell RNA sequencing of HLB infected/healthy leaves of resistance and susceptible selections.
Approach:
ARS's main focus is on objective 3 and 4:
In objective 3, USDA ARS will take use a combination of Pacbio and Nanopore sequencing platforms to sequence the genomes of select HLB resistant and susceptible hybrids. Short read DNA sequencing will be conducted on a larger populations of screened individuals. The data will be assessed and analyzed to identify potential QTL loci assocated with HLB resistance as well as important commercial fruit quality traits.
In objective 4, USDA ARS will develop protocols for single cell RNAseq using whole citrus leaves that have been infected with HLB as well as controls. Existing techniques developed for poplar leaves will be adapted for citrus to allow single cell profiling of leaves as well as profiling of ClaS bacterial transcripts simultaneously. The resulting data will be processed and analyzed to visualize cell-type specific expression responses in susceptible and HLB resistant citrus types to better understand the mechanisms of ClaS – host interactions.
