title: Salt stress reduces kernel number of corn by inhibiting plasma membrane H+-ATPase activity.
abstract: Salt stress affects yield formation of corn (Zea mays L.) at various physiological levels resulting in an overall grain yield decrease. In this study we investigated how salt stress affects kernel development of two corn cultivars (cvs. Pioneer 3906 and Fabregas) at and shortly after pollination. In an earlier study, we found an accumulation of hexoses in the kernel tissue. Therefore, it was hypothesized that hexose uptake into developing endosperm and embryo might be inhibited. Hexoses are transported into the developing endosperm by carriers localized in the plasma membrane (PM). The transport is driven by the pH gradient which is built up by the PM H+-ATPase. It was investigated whether the PM H+-ATPase activity in developing corn kernels was inhibited by salt stress, which would cause a lower pH gradient resulting in impaired hexose import and finally in kernel abortion. Corn grown under control and salt stress conditions was harvested 0 and 2 days after pollination (DAP). Under salt stress sucrose and hexose concentrations in kernel tissue were higher 0 and 2 DAP. Kernel PM H+-ATPase activity was not affected at 0 DAP, but it was reduced at 2 DAP. This is in agreement with the finding, that kernel growth and thus kernel setting was not affected in the salt stress treatment at pollination, but it was reduced 2 days later. It is concluded that inhibition of PM H+-ATPase under salt stress impaired the energization of hexose transporters into the cells, resulting in lower kernel growth and finally in kernel abortion.
authors.affiliation: Institute of Plant Nutrition (iFZ), Justus Liebig University, Giessen, Heinrich-Buff-Ring 26-32, 35392 Giessen, Germany. Electronic address: Stephan.Jung@agrar.uni-giessen.de.
authors.forename: Stephan
authors.initials: S
authors.lastname: Jung
authors.affiliation: Institute of Plant Nutrition (iFZ), Justus Liebig University, Giessen, Heinrich-Buff-Ring 26-32, 35392 Giessen, Germany.
authors.forename: Birgit W
authors.initials: BW
authors.lastname: Hütsch
authors.affiliation: Institute of Plant Nutrition (iFZ), Justus Liebig University, Giessen, Heinrich-Buff-Ring 26-32, 35392 Giessen, Germany.
authors.forename: Sven
authors.initials: S
authors.lastname: Schubert
mesh_terms: D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology; D002473:Cell Wall / Q000201:enzymology; D004789:Enzyme Activation; D057075:Enzyme Assays; D006601:Hexoses / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D010940:Plant Proteins / Q000009:adverse effects / Q000378:metabolism; D006180:Proton-Translocating ATPases / Q000378:metabolism*; D012639:Seeds / Q000187:drug effects / Q000201:enzymology / Q000254:growth & development; D012965:Sodium Chloride / Q000494:pharmacology*; D013312:Stress, Physiological / Q000187:drug effects / Q000502:physiology*; D013395:Sucrose / Q000378:metabolism; D003313:Zea mays / Q000187:drug effects* / Q000201:enzymology* / Q000254:growth & development / Q000378:metabolism
chemical_list: D006601:Hexoses; D010940:Plant Proteins; D012965:Sodium Chloride; D013395:Sucrose; D006180:Proton-Translocating ATPases
keywords: Corn; Hexose transport; Maize; Plasma membrane H(+)-ATPase; Salt stress; Source-sink relations; Zea mays L.