Submitted to: American Phytopathological Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: June 1, 2004
Publication Date: July 31, 2004
Citation: Janisiewicz, W.J., Bassett, C.L., Wisniewski, M.E., Conway, W.S., Roberts, D.P. Use of a luxgfp bioreporter system to determine metabolic activity of an antagonist in fruit wounds. American Phytopathological Society Abstracts.Abstract to be presented at Annual Meeting of the American Phytopathological Society, July 31 - August 4, 2004 in Anaheim, CA. Technical Abstract: Competition for nutrients has often been implicated as the main mechanism in biological control of postharvest diseases (BCPD) of fruits. High metabolic activity (MA) of the antagonists in fruit wounds (site of pathogen entry) should be essential for rapid removal of the limiting nutrients and for biocontrol to occur. To determine MA of the antagonist Pseudomonas syringae (L-59-66) in apple wounds, we constructed a derivative strain (L-GL-26) containing the luxgfp cassette. Bioluminescence due to expression of the lux cassette in L-GL-26 was proportional to MA of the cells and was easily quantified with a luminometer. Expression of gfp indicated the presence of the antagonist cells but not their MA. MA of the L-GL-26 cells in apple wounds declined greatly 48 h after application, but after the addition of 80 mM Asparagine, MA increased 3-fold within 2 h at 24°C. L-GL-26 cells applied to apple wounds after starvation in phosphate buffer for 72 h increased MA more than 100-fold after 2 h at 24°C. Our results indicate that this bioreporter system can be used to optimize conditions to maximize MA of the antagonist in apple wounds.