2012 Annual Report
2. To identify plant traits which impart resistance to the psyllid, traits that could be used to develop commercial citrus varieties with psyllid resistance for the purpose of reducing incidence of huanglongbing disease.
The objective of this project is to discover citrus germplasm with resistance to the Asian citrus psyllid. We have identified genotypes of Poncirus trifoliata and xCitroncirus sp. (hybrids of P. trifoliata and another parent species) that have resistance to the psyllid. We are now trying to identify the genotypic and phenotypic traits that promote resistance. Clear differences exist in the volatile profiles of susceptible and resistant plants. A project is being planned to analyze the amino acids, sugars, flavenoids, carrotenoids, isoprenoids, and sterols in phloem contents of germplasm that differs in psyllid susceptibility. This will provide information about the underlying reasons why some germplasm is psyllid-resistant and help identify traits that can be used in citrus breeding programs to confer psyllid resistance. Citrus that has been genetically transformed to express a plant defense protein is being evaluated for psyllid resistance.