Submitted to: Biological Control
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/24/2007
Publication Date: 6/12/2007
Citation: Zhang, S., Schisler, D.A., Boehm, M.J., Slininger, P.J. 2007. Utilization of chemical inducers of resistance and Cryptococcus flavescens OH 182.9 to reduce fusarium head blight under greenhouse conditions. Biological Control. 42:308-315. Interpretive Summary: Fusarium head blight (FHB) or scab of wheat is a devastating disease of wheat and barley worldwide. The pathogen causes significant losses in yield and quality when infections occur at or soon after flowering. In our laboratory, we previously discovered a yeast named Cryptococcus flavescens (C. nodaensis nomen nudum) OH 182.9 that reduces FHB disease in greenhouse and field tests. Improving the consistency of disease control by antagonists like strain OH 182.9 will greatly enhance their acceptance in the marketplace. We tested four well-known disease resistance inducing compounds [salicylic acid (SA), sodium salt of salicylic acid (NaSA), isonicotinic acid (INA), and DL-beta-amino-n-butyric acid (BABA)], and OH 182.9 separately or together for the ability to reduce FHB of wheat in greenhouse studies. NaSA and INA at a concentration of 10 millimolar (10 mM) reduced FHB disease when sprayed onto wheat heads at 3 days before pathogen inoculation. Combinations of NaSA or INA with OH 182.9 sometimes had a better effect in reducing FHB than any individual inducer or OH 182.9 alone, but this effect was not strong enough to be statistically significant. NaSA, INA and BABA at 1 mM substantially reduced FHB disease through induced systemic resistance when the compounds were applied to leaf sheaths that surrounding wheat heads approximately 10 days prior flowering. Induced FHB resistance was achieved by treating wheat with INA at concentrations as low as 0.1 mM. These results suggest that disease resistance inducing chemicals, biocontrol agents, and possibly the combination of these two methods could be developed into effective, environmentally friendly tools for use in the integrated management of FHB.
Technical Abstract: Four chemicals [salicylic acid (SA), sodium salt of salicylic acid (NaSA), isonicotinic acid (INA), and DL-beta-amino-n-butyric acid (BABA)], and the yeast antagonist Cryptococcus flavescens (= C. nodaensis nomen nudum) OH 182.9 were evaluated separately or together for the ability to reduce Fusarium head blight (FHB) of wheat in the greenhouse. When sprayed onto wheat heads at 3 days prior to pathogen challenge with Gibberella zeae, NaSA and INA at 10 mM significantly reduced FHB severity compared to the non-treated disease control. Applied at concentrations of 1 and 5 mM at 3 days before pathogen challenge, NaSA or INA in combination with OH 182.9 did not significantly reduce FHB severity compared to either treatment alone though the lowest disease severity values frequently were associated with the combination treatments. When sprayed onto wheat heads just beginning to emerge from boot at 10 days prior to pathogen inoculation, NaSA, INA, and BABA at 1 mM significantly reduced FHB severity indicating that induced systemic resistance was at least partially responsible for the reduction of FHB disease. Induced FHB resistance was achieved by treating wheat with INA at concentrations as low as 0.1 mM. In only one instance was one hundred-kernel weight affected by any chemical or combination of chemicals with OH 182.9 treatment. Data from our studies in the greenhouse suggest that chemical inducers can induce resistance in wheat against FHB, and that further efforts are warranted to explore the potential of improved control of FHB disease by incorporating chemical inducers with the FHB biocontrol agent OH 182.9.