Submitted to: Weed Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/6/2013
Publication Date: 7/1/2013
Citation: Horvath, D.P., Santana, M.A., Anderson, J.V. 2013. Microarray analysis of the semi-compatible pathogenic response and recovery of leafy spurge inoculated with the Cassava bacterial blight pathogen Xanthomonas axonopodis pv. manihotis. Weed Science. 61:428-436. Interpretive Summary: Xanthomonas axonopodis pv. manihotis (Xam) is a bacteria that causes a bacterial blight disease in cassava. Leafy spurge is a perennial invasive weed that is in the same plant family as cassava. Because no other closely related crop or native species from this plant family grows in areas impacted by leafy spurge, we tested to see if leafy spurge could be infected by Xam to determine if Xam may serve as a potential biocontrol agent for leafy spurge. Xam was able to colonize leafy spurge, but leafy spurge was able to readily recover from the infection. Since Xam devastates cassava crops when it infects them, we wanted to understand how leafy spurge was able to survive in hopes of transferring that knowledge to assist in protecting cassava from Xam. To do this, we looked at the expression of 23,000 genes to identify those that responded to Xam infection and recovery processes in leafy spurge. We identified about 900 genes that responded to Xam infection. Analysis of the likely function of these genes and the proteins that are known to turn these genes on and off in other well characterized systems, we determined that the plant hormone jasmonic acid may be specifically involved in recovery of leafy spurge following Xam infection.
Technical Abstract: Infection by Xanthomonas axonopodis pv. manihotis (Xam)of the model perennial range land weed leafy spurge was tested to see if Xam might serve a potential biological control agent for this invasive weed. Although leafy spurge was susceptible to Xam infection, it recovered with 21 days after inoculation (DAI). Microarray resources available for leafy spurge allowed us to follow physiological and signaling pathways that were altered as leafy spurge was infected and then recovered from Xam infection. The first physiological affect of Xam infection was a down-regulation of photosynthetic processes within 1 DAI. By 7 DAI numerous processes associated with well documented pathogenesis responses of plants was observed. Although some pathogenesis responses were still detectable at 21 DAI, other processes associated with meristem development were noted. Ontological analysis of potential signaling systems indicated jasmonic acid plays a significant role in the recovery processes.