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Title: Plant-based markers of infection for Neofusicoccum parvum

item Baumgartner, Kendra
item CZEMMEL, STEFAN - University Of Nevada
item CRAMER, GRANT - University Of Nevada
item Galarneau, Erin
item TRAVADON, RENAUD - University Of California
item LAWRENCE, DANIEL - University Of California
item McElrone, Andrew
item CANTU, DARIO - University Of California

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 11/20/2014
Publication Date: 11/20/2014
Citation: Baumgartner, K., Czemmel, S., Cramer, G.R., Galarneau, E.R., Travadon, R., Lawrence, D., Mcelrone, A.J., Cantu, D. 2014. Plant-based markers of infection for Neofusicoccum parvum. Workshop Proceedings. 9th International Workshop on Grapevine Trunk Diseases November 18-20, 2014, Adelaide, Australia.

Interpretive Summary:

Technical Abstract: Canopy symptoms of Botryosphaeria dieback do not appear until years after Neofusicoccum parvum infects a pruning wound. There are control practices to minimize such infections, but growers tend to wait until symptoms are visible, at which point disease prevention is far less effective. Toward development of an early detection tool that would identify infected plants in nurseries and vineyards, we used RNA-Seq to identify differentially-expressed genes in the leaves of inoculated vs. non-inoculated Cabernet Sauvignon in the greenhouse. Woody stems were examined using light microscopy and high resolution computed tomography (HRCT) to monitor the spread of infection, and its spatial and temporal relationships to wood anatomical changes. The early stage of infection occurred prior to 2 months post-inoculation (MPI), when spread of the pathogen beyond the inoculation site was the farthest. This incubation period was also characterized by the largest stem lesions, the highest levels of fungal colonization and xylem vessels fully-occluded by gels, and the lowest starch content in xylem fibers and rays. Prior to 2 MPI, RNA-Seq and validative qPCR analyses identified eight candidate genes, which were transcriptionally activated by infection, but not by wounding alone. The best candidate genes [a dehydrin, a BURP domain protein, and a peptide similar to abscisic acid-induced wheat plasma membrane polypeptide 19 (AWPM-19)] identified the pathogen’s presence with high specificity. Furthermore, expression of the eight candidate genes was not affected by Planococcus feeding, powdery or downy mildew infection, or abiotic stresses (heat, UV light), based on screenings of publicly-available, genome-wide expression data.