Location: Citrus and Other Subtropical Products Research
Project Number: 6034-41430-006-000-D
Project Type: In-House Appropriated
Start Date: Jul 14, 2015
End Date: Jun 4, 2020
Objective 1: Establish bioactive and sensory characteristics of new marketable genotypes (citrus, tomato, strawberry) and new Florida crops (avocado, blueberry, peach). Objective 2: Enable real-time, commercial pre- and postharvest treatments to optimize shelf life of new genotypes and new Florida crops using packaging, coatings, and maturity markers. Objective 3: Identify new sensory targets, enable new sensors, processing methods and management strategies to predict and mitigate HLB disease effects on citrus juice nutritional and flavor quality. Sub-Objective 3a: Identify chemical and biological markers that characterize the effect of HLB on fruit/juice quality. Sub-Objective 3b: Develop methods to mitigate the effect of HLB on citrus juice quality. Sub-Objective 3c: Develop methods to mitigate the effect of HLB on citrus fruit quality.
Phenotypes for fruit quality in citrus, tomatoes, strawberry, peaches and avocados will be screened for flavor markers: volatiles, sugars and acids, and sensory characteristics by gathering chemical and sensory data on a wide range of genetically variable breeding lines (or hybrids). In the long term, plant breeders will identify genes associated with fruit quality traits and map them on the genome to aid in marker-assisted selection. For advanced selections or commercial cultivars of peach and avocado, fruit will be harvested multiple times during maturation and ethylene and respiration rate will be measured at harvest and in stored fruit. For the effect of citrus greening or Huanglongbing (HLB) disease on orange fruit/juice flavor, fruit or juice will be obtained from collaborators, or from groves undergoing various field treatments (pesticides, growth regulators, antibiotics or thermotherapy), or from trees grown on different rootstocks to study a wide range of HLB flavor symptoms. Juices will be tested for CLas infection by qPCR and for levels of sugars, acids, volatiles, flavonoids, limonoids and for flavor perception using sensory evaluation. Taste panels will serve as the biosensors for compounds isolated from HLB-affected orange juice to determine compounds responsible for these putative off-flavor taste attributes. The electronic nose and electronic tongue will be used to screen for HLB-induced off-odor or flavor. The effect of HLB on the flavor quality of grapefruit and tangerines will be investigated. HLB-induced off-flavor can be managed by blending, by modifying juice processes or by adding citrus-derived natural compounds (volatiles or non-volatiles) to mask or bind off-flavor compounds. Studies will be conducted on several citrus types using fungicide sprays (strobulorins, Topsin) targeting D. natalensis to determine if the HLB-induced fruit drop and postharvest stem end rot can be reduced.