title: Stable radicals and biochemical compounds in embryos and endosperm of wheat grains differentiating sensitive and tolerant genotypes--EPR and Raman studies.
abstract: The aim of this study was to uncover the specific species in grains that might differentiate the wheat genotypes according to their tolerance to oxidative stress. Measurements by EPR and Raman spectroscopy techniques were used to examine whole grains and their parts (embryo, endosperm, seed coat) originating from four wheat genotypes with differing tolerance to drought stress. Raman spectra showed that, in spite of the similar amounts of proteins in whole grains from tolerant and sensitive genotypes, in tolerant ones they were accumulated mainly in embryos. Moreover, in embryos from these grains, a higher content of unsaturated fatty acids was observed. Endosperm of grains from the tolerant genotype, richer with starch than that of sensitive one, exhibited higher content of amylopectin. Detailed analysis of EPR signals and simulation procedures of the spectra allowed the estimation of the nature of interactions of Fe(III) and Mn(II) with organic and inorganic structures of grains and the character of organic stable radicals. Three types of these radicals: carbohydrate, semiquinone and phenoxyl, were identified. The amounts of these radicals were higher in grains of sensitive genotypes, mostly because of differences in carbohydrate radical content in endosperm. Taking into account the level of radical concentration and greater capacity for radical formation in grains from plants of lower tolerance to stress, the content of radicals, especially of a carbohydrate nature, was considered as a marker of the plant resistance to stress conditions.
authors.affiliation: Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Cracow, Poland. Electronic address: kurdziel@chemia.uj.edu.pl.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Kurdziel
authors.affiliation: Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Cracow, Poland. Electronic address: aleksandra@dlubacz.pl.
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Dłubacz
authors.affiliation: Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Cracow, Poland. Electronic address: birczyns@chemia.uj.edu.pl.
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Wesełucha-Birczyńska
authors.affiliation: Department of Biochemistry, Biophysics and Biotechnology, Institute of Biology, Pedagogical University, Podchorążych 2, 30-084 Cracow, Poland; The Franciszek Górski Institute of Plant Physiology, Polish Academy of Sciences, Niezapominajek 21, 30-239 Cracow, Poland. Electronic address: mariafilek@excite.com.
authors.forename: Maria
authors.initials: M
authors.lastname: Filek
authors.affiliation: Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Cracow, Poland. Electronic address: labanows@chemia.uj.edu.pl.
authors.forename: Maria
authors.initials: M
authors.lastname: Łabanowska
mesh_terms: D055864:Droughts; D004578:Electron Spin Resonance Spectroscopy; D056625:Endosperm / Q000235:genetics / Q000378:metabolism; D005838:Genotype; D018384:Oxidative Stress; D012639:Seeds / Q000235:genetics / Q000378:metabolism; D013059:Spectrum Analysis, Raman; D014908:Triticum / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism
keywords: EPR spectroscopy; Raman spectroscopy; Stable organic radicals; Stress tolerance; Wheat grains