Submitted to: American Phytopathological Society Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: August 3, 2005
Publication Date: July 20, 2005
Citation: Schisler, D.A. 2005. Flowering wheat heads as novel colonization sites for Gibberella zeae and introduced antagonists [abstract]. American Phytopathological Society Annual Meeting. Phytopathology 95:S129. Technical Abstract: Gibberella zeae is a causal agent of Fusarium head blight (FHB), a damaging disease of wheat and barley. Infection proceeds primarily via penetration of the adaxial surfaces of the palea and lemma tissues of a spikelet though anthers also have been implicated in the infection process. The compounds choline and betaine are structurally similar and found in wheat anthers and other head tissues. These compounds can influence microbial and plant physiology via enhancing tolerance to environmental stresses including cold and osmotic. Several, but not all, reports suggest that these compounds also stimulate the growth of conidial germ tubes of G. zeae. Microbial colonists that rapidly utilize these compounds on wheat heads hypothetically would survive environmental stress to a greater extent and may reduce pathogen infection success by preemptively removing a growth signal used by the pathogen. When choline chloride was supplied as a sole carbon source in liquid culture, 122 choline metabolizing strains (CMS) from wheat anthers were identified out of 738 (16.5%) strains assayed. Twelve CMS with FHB biocontrol activity in greenhouse assays were selected for field testing. Four of 12 CMS reduced FHB symptoms at both of the sites and on both of the wheat varieties tested. In separately conducted tests, Cryptococcus nodaensis OH182.9, a non-CMS yeast antagonist that was isolated from wheat anthers, maintained or increased in population even when applied to heads prior to anther extrusion. Additional studies on choline and betaine are needed to clarify the role of these compounds in FHB disease development.