Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 10/1/2004
Publication Date: 10/1/2004
Citation: Schisler, D.A., Zhang, S., Boehm, M.J., Jackson, M.A. 2004. Advances in developing biological control products active against fusarium head blight of wheat [abstract]. Proceedings of the International Scientific and Practical Conference. Biological Plant Protection as a Basis for Stabilizing Agroecosystems. Krasnodar, Russia. Book 3, p. 10.
Technical Abstract: Fresh and frozen concentrates of Cryptococcus nodaensis OH 182.9 (NRRL Y-30216, patent culture collection) cells have reduced Fusarium head blight (FHB) in multiple greenhouse and field trials. Development of a dried commercial product of OH 182.9 would have potential advantages of ease of handling, favorable economics, and acceptance by end users. In experiments designed to test the effect of temperature shock during cell growth on the survival of OH 182.9 after air-drying, cells were grown at various temperatures in semidefined complete liquid media (SDCL), with cells grown at 25 deg C for 48 h serving as a control. Harvested cultures were mixed with 5 or 10% diatomaceous earth (Hyflo), vacuum filtered, air dried for 15-20 h at 60-70% RH and cell survival at 4 deg C evaluated for 14 weeks. In general, cells grown at 25 deg C for 20 h and then cold shocked at 15 deg C for 28 h survived air-drying better than cells from the control. The survival of cells subjected to heat shock at 31 deg C generally did not differ from control cells regardless of the stage of cell growth when heat shock was applied. The influence of type and grade of filtering agent on cell survival is currently being explored as a prelude to commercial-scale tests of a dried OH 182.9 biocontrol product. In related work designed to potentially increase the efficacy and consistency of FHB biocontrol, choline-utilizing strains (CUS) from wheat anthers were sought to combine with strain OH 182.9. Choline in wheat anthers can stimulate growth of conidial germ tubes of Gibberella zeae, suggesting that choline-utilizing strains may be effective competitors of the pathogen. When choline chloride was supplied as a sole carbon source in liquid culture, 122 CUS were identified out of 738 (16.5%) strains assayed using a colorimetric, choline oxidase-based bioassay. Four of 12 CUS tested reduced FHB symptoms at two field sites on two wheat varieties. A Gram-positive bacterial CUS AS 54.6 reduced disease severity by 17-60% on winter wheat variety Pioneer 2545.