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ARS Home » Southeast Area » Fort Pierce, Florida » U.S. Horticultural Research Laboratory » Citrus and Other Subtropical Products Research » Research » Research Project #437398

Research Project: Development of Huanglongbing (HLB) Resistance Through Inarching Novel, Disease Tolerant Hybrids and Through Breeding

Location: Citrus and Other Subtropical Products Research

Project Number: 6034-21000-019-04-R
Project Type: Reimbursable Cooperative Agreement

Start Date: Oct 1, 2017
End Date: Sep 30, 2020

Objective:
The overall objective of the project is to develop novel citrus hybrids that confer reduced susceptibility to Huanglongbing disease. Specific objectives include: 1) field evaluation of novel citrus hybrids with which may reduce susceptibility to Huanglongbing in the field in Florida; 2) generation of inarched citrus trees with novel citrus hybrids along with evaluation of susceptibility to Huanglongbing in Florida and California (years 1,2,3); and 3). Screen trifoliate hybrids for susceptibility to Huanglongbing (years 1, 2, 3).

Approach:
In previous years of this research we have screened approximately three hundred novel citrus hybrids for susceptibility to Huanglongbing disease. Hybrids are exposed to Asian citrus psyllids, insect vector of Candidatus Liberibacter asiaticus, the bacterium that causes Huanglongbing. Our approach in the screening protocol is to expose the citrus hybrids to Asian citrus psyllids infected with the Huanglongbing pathogen in the greenhouse. Following exposure, plants are monitored for incidence of infection with Candidatus Liberibacter asiaticus and development of Huanglongbing symptoms. Several hybrids have been identified as less susceptible to Huanglongbing compared to others. Propagations of these hybrids have been prepared. Objective 1: During this project the hybrids propagations will be planted in the field for observation of tree growth and development and expression of Huanglongbing symptoms. Objective 2: Inarching is a horticultural practice that can be used to rehabilitate citrus trees that are affected by biotic stressors. Based on apparent reduced susceptibility to Huanglongbing disease, five hybrids were selected and will be inarched to standard citrus rootstock scion combinations. We will then test the hypothesis that there may a transmissible factor that moves from the inarched rootstock and into the scion to provide reduced susceptibility to Huanglongbing disease. Experiments will be conducted in both the greenhouse and the field.