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United States Department of Agriculture

Agricultural Research Service

Research Project: SEMIOCHEMICALS FOR THE MANAGEMENT OF AGRICULTURAL PESTS

Location: Crop Bioprotection Research

Title: Characterization of the surface properties of wheat spikelet components grown under different regimes and the biocontrol yeast Cryptococcus flavescens

Authors
item Dunlap, Christopher
item Schisler, David

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 11, 2014
Publication Date: January 29, 2014
Citation: Dunlap, C.A., Schisler, D.A. 2014. Characterization of the surface properties of wheat spikelet components grown under different regimes and the biocontrol yeast Cryptococcus flavescens. Journal of Agricultural and Food Chemistry. 62(1):809-815.

Interpretive Summary: Wheat scab is an important disease of wheat that infects the wheat head. To better understand how the plant pathogen interacts with the plant we have characterized the surface properties of wheat head components of two wheat cultivars with different susceptibility to Fusarium head blight. In addition, we examined how these properties differ for wheat grown in a greenhouse environment versus wheat grown in the field. The ability of water to wet surfaces of wheat heads varied with wheat cultivar and whether the wheat was field grown or not. Knowledge of these properties will help us make decisions in developing crop protection products with improved adherence to the wheat head. In addition, the research will allow us to determine how these properties affect the interaction of beneficial or harmful microorganisms with wheat. Understanding how these properties impact plant diseases has the potential to lead to new methods of crop protection for wheat farmers.

Technical Abstract: The physicochemical surfaces properties of wheat (Triticum aestivum L) spikelet components have been characterized under different environmental growing regimes. Wheat samples grown in a greenhouse environment were compared with samples produced in the field for two wheat cultivars (Freedom and Pioneer Brand 2545). Wheat spikelets were sampled at the following growth stages; split boot (early Feekes 10.1), out of boot (Feekes 10.5), flowering (Feekes 10.5.1) and at 4, 8, and 12 days after flowering. The results show changes occurring in the surface energy parameters and estimates of roughness during this period between the two cultivars with Pioneer Brand 2545 averaging higher surface energies during greenhouse growth. In general, the greenhouse samples were more hydrophobic than those grown in the field. Field grown samples experienced a significant drop in surface energy parameters during flower emergence. In addition, the surface energy parameters for the biocontrol yeast, Cryptococcus flavescens OH 182.9 (NRRL Y-30216) were determined from contact angles on microbial lawns. The results determined the cells are hydrophobic with a free energy of aggregation of -86.3 mJ/m2 in water. These results are inconsistent with observations they are readily dispersible in water, but they rapidly foul a membrane during the filtering process for microbial lawn formation. These inconsistencies suggested a surface altering phenomenon during the filtering process. The role of divalent metals in this phenomenon was explored using metal chelators during the filtering process. The results suggest that divalent ions play a role in the phenomenon, but are not the sole determinant.

Last Modified: 11/26/2014
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