title: Large-Scale Proteomics of the Cassava Storage Root and Identification of a Target Gene to Reduce Postharvest Deterioration.
abstract: Cassava (Manihot esculenta) is the most important root crop in the tropics, but rapid postharvest physiological deterioration (PPD) of the root is a major constraint to commercial cassava production. We established a reliable method for image-based PPD symptom quantification and used label-free quantitative proteomics to generate an extensive cassava root and PPD proteome. Over 2600 unique proteins were identified in the cassava root, and nearly 300 proteins showed significant abundance regulation during PPD. We identified protein abundance modulation in pathways associated with oxidative stress, phenylpropanoid biosynthesis (including scopoletin), the glutathione cycle, fatty acid α-oxidation, folate transformation, and the sulfate reduction II pathway. Increasing protein abundances and enzymatic activities of glutathione-associated enzymes, including glutathione reductases, glutaredoxins, and glutathione S-transferases, indicated a key role for ascorbate/glutathione cycles. Based on combined proteomics data, enzymatic activities, and lipid peroxidation assays, we identified glutathione peroxidase as a candidate for reducing PPD. Transgenic cassava overexpressing a cytosolic glutathione peroxidase in storage roots showed delayed PPD and reduced lipid peroxidation as well as decreased H2O2accumulation. Quantitative proteomics data from ethene and phenylpropanoid pathways indicate additional gene candidates to further delay PPD. Cassava root proteomics data are available at www.pep2pro.ethz.ch for easy access and comparison with other proteomics data.
authors.affiliation: Department of Biology, ETH Zurich, 8092 Zurich, Switzerland hvanderschuren@ethz.ch.
authors.forename: Hervé
authors.identifier: http://orcid.org/0000-0003-2102-9737
authors.initials: H
authors.lastname: Vanderschuren
authors.affiliation: Department of Biology, ETH Zurich, 8092 Zurich, Switzerland.
authors.forename: Evans
authors.initials: E
authors.lastname: Nyaboga
authors.affiliation: Department of Biology, ETH Zurich, 8092 Zurich, Switzerland.
authors.forename: Jacquelyne S
authors.initials: JS
authors.lastname: Poon
authors.affiliation: Department of Biology, ETH Zurich, 8092 Zurich, Switzerland.
authors.forename: Katja
authors.identifier: http://orcid.org/0000-0002-1904-9440
authors.initials: K
authors.lastname: Baerenfaller
authors.affiliation: Functional Genomics Center Zurich, UZH/ETH, 8057 Zurich, Switzerland.
authors.forename: Jonas
authors.initials: J
authors.lastname: Grossmann
authors.affiliation: Department of Biology, ETH Zurich, 8092 Zurich, Switzerland.
authors.forename: Matthias
authors.initials: M
authors.lastname: Hirsch-Hoffmann
authors.affiliation: Institute of Agricultural Sciences, ETH Zurich, 8092 Zurich, Switzerland.
authors.forename: Norbert
authors.initials: N
authors.lastname: Kirchgessner
authors.affiliation: Functional Genomics Center Zurich, UZH/ETH, 8057 Zurich, Switzerland.
authors.forename: Paolo
authors.initials: P
authors.lastname: Nanni
authors.affiliation: Department of Biology, ETH Zurich, 8092 Zurich, Switzerland.
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Gruissem