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LOGO: Journal of Cotton Science


Ability of Indigenous Yeasts from Aerial Plant Surfaces to Degrade Sugars from Insect Honeydew

Authors: Vern J. Elliott
Pages: 60-67
Plant Pathology and Nematology

Sticky cotton occurs when late-season whitefly or aphid infestations result in honeydew deposition on the lint. Contamination of cotton lint by insect honeydew poses a serious problem for ginning and processing because sugars foul equipment and cause the lint to stick to machinery. Bioremediation, the degradation of compounds by living organisms, offers a possible method of removing this contamination. The yeasts that colonize aerial plant surfaces are potential sources of bioremediation agents. Our research characterized the indigenous yeast population from the aerial surfaces of cotton and other plants growing in the San Joaquin Valley of California for its ability to utilize some honeydew sugars. Yeast strains collected in the field were tested in the laboratory for growth on sucrose, glucose, fructose, melezitose, trehalose, or cellobiose. All sugars tested could be degraded by many of the 250 yeast strains tested, and a wide range of growth rates of the yeast strains was observed on individual sugars. The mean growth rate was highest on sucrose followed by glucose, fructose, cellobiose, trehalose, and melezitose. The 250 yeast strains were grouped with cluster analysis into five major functional groups on the basis of sugar utilization. Many strains could utilize several or all the sugars, and within a single strain, growth rates on different sugars were correlated. These results provide an important characterization of the carbohydrate utilization capabilities of the indigenous yeast population on plants and indicate the potential for selecting bioremediation strains of yeast from the local yeast population.