title: Volatile emission in dry seeds as a way to probe chemical reactions during initial asymptomatic deterioration.
abstract: The nature and kinetics of reactions in dry seeds determines how long the seeds survive. We used gas chromatography to assay volatile organic compounds (VOCs) emitted from seeds of three unrelated species as a means to non-invasively probe chemical changes during very dry, dry, and humid storage (seeds were dried to 5.5, 33, and 75% relative humidity at room temperature). VOCs emitted from seeds stored in humid conditions reflected fermentation-type reactions, with methanol and ethanol being predominant in Lactuca sativa and Carum carvi, and acetaldehyde and acetone being predominant in Eruca vesicaria. Dried C. carvi seeds continued to emit fermentation-type products, although at slower rates than the seeds stored in humid conditions. In contrast, drying caused a switch in VOC emission in L. sativa and E. vesicaria seeds towards higher emission of pentane and hexanal, molecules considered to be byproducts from the peroxidation of polyunsaturated fatty acids. Longevity correlated best with the rate of fermentation-type reactions and appeared unrelated to the rate of lipid peroxidation. Emission of VOCs decreased when seed species were mixed together, indicating that seeds adsorbed VOCs. Adsorption of VOCs did not appear to damage seeds, as longevity was not affected in seed mixtures. Collectively, the study shows similarity among species in the types of reactions that occur in dry seeds, but high diversity in the substrates, and hence the byproducts, of the reactions. Moreover, the study suggests that the most abundant VOCs arise from degradation of storage reserves within seed cells, and that these reactions and their byproducts are not, in themselves, damaging.
authors.affiliation: Departamento de Biotecnología-Biología Vegetal, E.T.S.I. Agrónomos, Universidad Politécnica de Madrid, Madrid, Spain USDA Agricultural Research Service, National Center for Genetic Resources Preservation, 1111 South Mason St, Fort Collins, CO 80524, USA.
authors.forename: Sara
authors.initials: S
authors.lastname: Mira
authors.affiliation: USDA Agricultural Research Service, National Center for Genetic Resources Preservation, 1111 South Mason St, Fort Collins, CO 80524, USA.
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Hill
authors.affiliation: Departamento de Biotecnología-Biología Vegetal, E.T.S.I. Agrónomos, Universidad Politécnica de Madrid, Madrid, Spain.
authors.forename: M Elena
authors.initials: ME
authors.lastname: González-Benito
authors.affiliation: Departamento de Economía Agraria, Estadística y Gestión de Empresas, E.T.S.I. Agrónomos, Universidad Politécnica de Madrid, Madrid, Spain.
authors.forename: Miguel Angel
authors.initials: MA
authors.lastname: Ibáñez
authors.affiliation: USDA Agricultural Research Service, National Center for Genetic Resources Preservation, 1111 South Mason St, Fort Collins, CO 80524, USA christina.walters@ars.usda.gov.
authors.forename: Christina
authors.initials: C
authors.lastname: Walters
mesh_terms: D029974:Carum / Q000378:metabolism; D003890:Desiccation; D005227:Fatty Acids / Q000378:metabolism; D018525:Germination; D006813:Humidity; D007700:Kinetics; D018545:Lactuca / Q000378:metabolism; D012639:Seeds / Q000378:metabolism*; D013696:Temperature; D013997:Time Factors; D055549:Volatile Organic Compounds / Q000378:metabolism*
chemical_list: D005227:Fatty Acids; D055549:Volatile Organic Compounds
keywords: Fermentation; gas chromatography; methanol; pentane; peroxidation; seed aging; seed quality markers; seed storage; volatile organic compounds; water content.