title: Barium toxicity effects in soybean plants.
abstract: Barium (Ba)-induced phytotoxicity at 100, 1000, or 5000 microM Ba in soybean plants (Glycine max) was investigated under hydroponic culture conditions. Soybean growth and leaf photosynthetic activity were significantly inhibited by all three levels of Ba treatments. In the case of photosynthetic activity, 5000 microM Ba treatment shutdown stomatal opening and perturbed carbon fixation metabolism and translocation. However, 100 and 1000 microM Ba treatments shut down stomatal opening and inhibited carbon fixation, but without perturbation of leaf carbon fixation-related metabolism. Potassium (K) absorption by soybean roots was also reduced in all three Ba treatments. This decreased K absorption reduced K localization at guard cells. Barium accumulation in guard cells also inhibited K transport from epidermal cells to guard cells. This lack of K in guard cells resulted in stomatal closure. As a result of inhibition of K transport into guard cells and stomatal shutdown, photosynthetic activity and plant productivity were inhibited. Our experiment indicates that Ba has phytotoxic effects on soybean plants by inhibiting photosynthesis.
authors.affiliation: Graduate School of Biosphere Science, Hiroshima University, 1-4-4 Kagamiyama, Higashi-Hiroshima, 739-8528, Japan.
authors.forename: Ryuichi
authors.initials: R
authors.lastname: Suwa
authors.forename: Krish
authors.initials: K
authors.lastname: Jayachandran
authors.forename: Nguyen Tran
authors.initials: NT
authors.lastname: Nguyen
authors.forename: Abdellah
authors.initials: A
authors.lastname: Boulenouar
authors.forename: Kounosuke
authors.initials: K
authors.lastname: Fujita
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Saneoka
mesh_terms: D001464:Barium / Q000032:analysis / Q000633:toxicity*; D002118:Calcium / Q000032:analysis; D004305:Dose-Response Relationship, Drug; D010788:Photosynthesis / Q000187:drug effects; D018515:Plant Leaves / Q000187:drug effects / Q000254:growth & development / Q000502:physiology; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development / Q000502:physiology; D018547:Plant Stems / Q000187:drug effects / Q000254:growth & development / Q000502:physiology; D011188:Potassium / Q000032:analysis; D012989:Soil Pollutants / Q000032:analysis / Q000633:toxicity*; D013025:Glycine max / Q000187:drug effects* / Q000254:growth & development / Q000502:physiology; D014867:Water / Q000032:analysis
chemical_list: D012989:Soil Pollutants; D014867:Water; D001464:Barium; D011188:Potassium; D002118:Calcium