Project Number: 6034-41430-007-03-I
Project Type: Interagency Reimbursable Agreement
Start Date: Jan 15, 2018
End Date: Jan 14, 2023
Identify Huanglongbing (HLB)-tolerant scion cultivars that can be quickly mobilized for use by the U.S. citrus industry. We will 1) identify HLB-resistant/tolerant hybrids with good flavor (including orange-like and grapefruit-like) quality; 2) Identify deoxyribonucleic acid (DNA) markers associated with tolerance to expedite screening and provide confidence in scion genotypes considered promising and explore tolerance-related responses to pathogen effectors/Pathogen-associated molecular patterns (PAMPS), for use as a screening tool; 3) develop a transgenic strategy to enhance cultivars resistance responses; 4) characterize fruit and juice quality of HLB-tolerant scions, for use either as stand-alone varieties, hybrid classification as “orange” and/or development of juice combinations to supplement the current processing stream; and 5) communicate these results to facilitate industry implementation of HLB-tolerant scion cultivars.
Huanglongbing (HLB) resistance/tolerance will be assessed and identified in existing cultivars and advanced selections in the USDA, University of California, Riverside (UCR) and University of Florida (UF) citrus breeding programs. These will be evaluated for fruit/juice quality including orange (or grapefruit) like characteristics using chemical and sensory analyses. Aroma profiles of top candidates would then be used to classify some hybrids as “orange” or “grapefruit” for commercial release and use, and/or identify blends that resemble orange or grapefruit juice, increasing fruit supply to processing plants (and packing houses) to prevent loss of this infrastructure. Molecular markers for HLB tolerance/resistance will be identified and validated. Thus, identification of HLB-tolerant or resistant genotypes in field trials is critical, and this process will be expedited by molecular markers that are clearly associated with tolerance/resistance in citrus hybrids. Use of molecular markers will improve the efficiency and precision of conventional plant breeding through marker-assisted selection of existing and future hybrids. Finally, this proposal aims to design citrus immune receptors to enhance perception of CLas with the ultimate goal of engineering resistant/or tolerant citrus.