title: Indole-3-acetic acid-producing yeasts in the phyllosphere of the carnivorous plant Drosera indica L.
abstract: Yeasts are widely distributed in nature and exist in association with other microorganisms as normal inhabitants of soil, vegetation, and aqueous environments. In this study, 12 yeast strains were enriched and isolated from leaf samples of the carnivorous plant Drosera indica L., which is currently threatened because of restricted habitats and use in herbal industries. According to similarities in large subunit and small subunit ribosomal RNA gene sequences, we identified 2 yeast species in 2 genera of the phylum Ascomycota, and 5 yeast species in 5 genera of the phylum Basidiomycota. All of the isolated yeasts produced indole-3-acetic acid (IAA) when cultivated in YPD broth supplemented with 0.1% L-tryptophan. Growth conditions, such as the pH and temperature of the medium, influenced yeast IAA production. Our results also suggested the existence of a tryptophan-independent IAA biosynthetic pathway. We evaluated the effects of various concentrations of exogenous IAA on yeast growth and observed that IAA produced by wild yeasts modifies auxin-inducible gene expression in Arabidopsis. Our data suggest that yeasts can promote plant growth and support ongoing prospecting of yeast strains for inclusion into biofertilizer for sustainable agriculture.
authors.affiliation: Department of Biology, National Changhua University of Education, Changhua 500, Taiwan, R.O.C.
authors.forename: Pei-Feng
authors.initials: PF
authors.lastname: Sun
authors.affiliation: Graduate Institute of Environmental Education, National Taiwan Normal University, Taipei 116, Taiwan, R.O.C.
authors.forename: Wei-Ta
authors.initials: WT
authors.lastname: Fang
authors.affiliation: Department of Biology, National Changhua University of Education, Changhua 500, Taiwan, R.O.C.
authors.forename: Li-Ying
authors.initials: LY
authors.lastname: Shin
authors.affiliation: Department of Biology, National Changhua University of Education, Changhua 500, Taiwan, R.O.C.
authors.forename: Jyuan-Yu
authors.initials: JY
authors.lastname: Wei
authors.affiliation: Department of Biology, National Changhua University of Education, Changhua 500, Taiwan, R.O.C.
authors.forename: Shih-Feng
authors.initials: SF
authors.lastname: Fu
authors.affiliation: Department of Biology, National Changhua University of Education, Changhua 500, Taiwan, R.O.C.
authors.forename: Jui-Yu
authors.initials: JY
authors.lastname: Chou
mesh_terms: D029787:Drosera / Q000378:metabolism*; D007210:Indoleacetic Acids / Q000378:metabolism*; D015003:Yeasts / Q000254:growth & development / Q000378:metabolism*
chemical_list: D007210:Indoleacetic Acids; C030737:indoleacetic acid