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United States Department of Agriculture

Agricultural Research Service

Research Project: Development of an integrated research plan for management of Zebra Chip in potatoes
2012 Annual Report


1a.Objectives (from AD-416):
Design a ZC specific realtime PCR diagnosis for reliable detections of ZC-infected potato and potato psyllid. 2. Design and develop multi-locus DNA Simple Sequence Repeat (SSR) DNA markers to genotype and assess genetic diversity of ZC-associated Liberibacter bacteria.


1b.Approach (from AD-416):
1. Clone and sequence ZC Liberibacter pathogen to identify suitable sequencing regions for designing realtime PCR. Validate sensitivity and specificity of detection. 2. Conduct whole genome analyze of ZC Liberibacter draft genome and identify SSR loci for designing SSR primers. 3. Conduct population genetic analysis of ZC-associated Candidatus Liberibacter and assess genetic diversity of the pathogen.


3.Progress Report:

Results of this study are in support of Objective 1 of the parent project. The goal of the project is to develop new molecular markers for identification and assessment of genetic diversity of ‘Candidatus Liberibacter solanacearum’ (CLso), a bacterium associated with potato zebra chip disease. The available genome sequence of CLso permits development of a genome-based multilocus sequence typing (MLST) marker system for detection and genetic analysis of CLso. Using this marker system, genetic relationships among CLso strains in North America (USA and Mexico) and New Zealand were characterized. MLST analysis differentiated 59 strains into two sequencing types (ST-1 and ST-2). Both types are present among US strains while only one type was detected in Mexico (ST-1) and New Zealand (ST-2), respectively. This marker system provides a useful tool for genotyping and assessing genetic diversity of ‘Ca. L. solanacearum’ strains.


Last Modified: 12/20/2014
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