2010 Annual Report
2) Identify molecular and biological mechanisms of citrus HLB and control of the disease
The project is currently at the second year. The following is a summary of the research results.
1) Genetic diversity of the HLB pathogens in China and the United State Samples from various HLB-infected citrus varieties were collected both from China and the United States, and the DNAs were isolated and subjected to genetic diversity studies based on the hyper-variable regions of the HLB bacterium, ‘Candidatus Liberibacter asiaticus’(Las). Sequence analysis of the hyp1 and hyp2 genes of these isolates indicated their genetic diversity between these two origins, which suggested the Las strain in Florida is different from those in China.
2) Microbial ecology of the HLB-infected citrus plants and its insect vectors, the Asian citrus psyllids
Samples from three different varieties (Citrus tangerine, C. sinensis, C. reticulata) of citrus plants with and without HLB disease were collected and subjected to microbial ecology studies using phospholipid fatty acid (PLFA) analysis. Different PLFA biomarkers were revealed from HLB-infected vs. non-infected plants. These markers will be further evaluated against broader host ranges (varieties) and number of samples to identify useful markers for diagnostics. Microbial community dynamics in the psyllids with and without Las bacterium is under investigation using PLFA and cloning/sequencing of the 16S rDNAs.
Monitoring was provided by emails and site visits.