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ARS Home » Pacific West Area » Parlier, California » San Joaquin Valley Agricultural Sciences Center » Crop Diseases, Pests and Genetics Research » Research » Publications at this Location » Publication #323082

Title: Candidatus liberibacter associated diseases: challenges and opportunities

item Lin, Hong

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 10/22/2015
Publication Date: 10/29/2015
Citation: Lin, H. 2015. Candidatus liberibacter associated diseases: challenges and opportunities. The Second International Horticulture Research Conference, October 29-November 2, 2015, Davis, California. p.35.

Interpretive Summary:

Technical Abstract: ‘Candidatus Liberibacter’ species are Gram-negative, phloem-limited bacteria which are members of the Rhizobiaceae a-Proteobacteria. These bacteria are naturally transmitted by psyllid insects. Most of the disease-associated Liberibacters are designated ‘Candidatus’ species because they have not been cultured in vitro. Thus, Koch’s postulates have not been fulfilled. Citrus huanglongbing (HLB) is associated with three different species of ‘Ca. Liberibacter’ – ‘Ca. L. asiaticus’, ‘Ca. L. africanus’, and ‘Ca. L. americanus’, each named based on presumptive origin. ‘Ca. Liberibacter solanacearum’ causes diseases in several solanaceous plants, including potato Zebra chip disease, and is transmitted by the potato psyllid Bactericera cockerelli. Zebra chip disease is causing significant damage in potato crops in North America. Since the causative agents are not culturable, information regarding genetics and pathogenesis is limited. In spite of these challenges, complete genome sequences from multiple Liberibacter species have been determined. Comparative analyses of four Liberibacter genomes provide unprecedented insights into evolutionary history, and phylogenetic and metabolomic capacities of these bacteria. In addition, genomic analyses of plant disease-associated Liberibacters have led to identification of potential or putative pathogenicity and virulence factors. The availability of specific biomarkers associated with Liberibacter-host plant interactions will aid in development of improved, reliable diagnostic protocols for early detection (i.e. pre-symptomatic) as part of disease management strategies. Knowledge of specific Liberibacter genes and their products associated with pathogenicity and virulence, as well as interactions with psyllid vectors, has led to identification of potential targets for mitigating Liberibacter acquisition, transmission by psyllids, and disease development. Finally, genomics-based research will facilitate improved understanding of the complex and diverse mechanisms of Liberibacter – plant interactions.