1a. Objectives (from AD-416):
1. Develop metabolic profiles of host responses to “Candidatus Liberibacter” associated diseases. 2. Identify genes involving defensive pathways to pathogen infections.
1b. Approach (from AD-416):
1. Use gas chromatography-mass spectrometry (GC/MS) and high perform liquid chromatography (HPLC) to develop citrus huanglongbing and potato zebra chip metabolic profiles. 2. Use matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOF-MS/MS)to identify candidate genes and pathways involving in defensive responses to Liberibacter infections. 3. Identified compounds and amino acid sequences will be compiled by querying the KEGG pathway databases to establish metabolic networks.
3. Progress Report:
This research is in support of Objective 2 of the in-house project, the goal of which is to identify molecular and physiological mechanisms of plants in response to disease. Molecular profiling of healthy and Liberibacter-infected citrus and potato plants were executed. Over 200 differentially expressed gene products and proteins were identified in citrus and potato leaf tissues in response to infection. Despite down-regulation of photosynthesis-related genes/proteins, over 60% of the differentially produced gene transcripts/proteins were up-regulated, particularly in above-ground tissues. Further nutritional analysis of key elements showed an increase in concentration of K, Mn, Fe and Cu in above-ground and below-ground tissues in response to zebra chip disease. These results further complement results from citrus huanglongbing studies that identified biochemical mechanisms associated with disease development. These studies advanced understanding of host-pathogen interactions and will contribute to improvement of disease diagnosis and understanding of host resistance to diseases caused by Liberibacter species.