Understanding Bacterial Virulence Genes and Mechanisms of Host Response to Insect-Mediated Citrus Huanglongbing

摘要

A summary is provided for research progress in studying genomics and proteomics of molecular pathogen-host interactions for citrus huanglongbing (HLB), a destructive disease of citrus that presents a major threat to the citrus industries in US as wellas other citrus production regions in the world. The disease is associated with a gram-negative, phloem-limited, insect-vectored, unculturable prokaryote: ' Candidates Liberibacter spp', that belong to the Rhizobiaceae family of a -Proteobacteria. Despite the fact that Koch's postulates have not been fulfilled, a considerable progress has been made in understanding molecular basis of HLB disease since the publication of HLB-associated Liberibacter genome. Annotation of the Liberibacter genome sequencehas provided insights into the genetic basis of the virulence, physiological and metabolic capabilities of this organism. Functional determination of key virulence genes will permit researchers to design and develop a novel gene-based therapeutic treatment to control the disease. Since most commercial citrus cultivars are susceptible to HLB, understanding the molecular mechanisms of host response is crucial for the development and deployment of HLB-resistant citrus varieties. A long term and sustainablemanagement of HLB is likely to be based on integrated strategies including removal or reduction of vectors or inocula, and the improvement of host resistance to HLB-associated Liberibacters and psyllid vectors.