title: Bioaccumulation and effects of lanthanum on growth and mitotic index in soybean plants.
abstract: Rare earth elements such as lanthanum (La) have been used as agricultural inputs in some countries in order to enhance yield and improve crop quality. However, little is known about the effect of La on the growth and structure of soybean, which is an important food and feed crop worldwide. In this study, bioaccumulation of La and its effects on the growth and mitotic index of soybean was evaluated. Soybean plants were exposed to increasing concentrations of La (0, 5, 10, 20, 40, 80, and 160 µM) in nutrient solution for 28 days. Plant response to La was evaluated in terms of plant growth, nutritional characteristics, photosynthetic rate, chlorophyll content, mitotic index, modifications in the ultrastructure of roots and leaves, and La mapping in root and shoot tissues. The results showed that the roots of soybean plants can accumulate sixty-fold more La than shoots. La deposition occurred mainly in cell walls and in crystals dispersed in the root cortex and in the mesophyll. When La was applied, it resulted in increased contents of some essential nutrients (i.e., Ca, P, K, and Mn), while Cu and Fe levels decreased. Moreover, low La concentrations stimulated the photosynthetic rate and total chlorophyll content and lead to a higher incidence of binucleate cells, resulting in a slight increase in roots and shoot biomass. At higher La levels, soybean growth was reduced. This was caused by ultrastructural modifications in the cell wall, thylakoids and chloroplasts, and the appearance of c-metaphases.
authors.affiliation: Department of Soil Science, Federal University of Lavras, CP 3037, Campus UFLA, Lavras 37200-000, Brazil.
authors.forename: Cynthia
authors.initials: C
authors.lastname: de Oliveira
authors.affiliation: Vale Institute of Technology-Mining, 31 Juscelino Kubitschek Avenue, Bauxita Ouro Preto 35400-000 Brazil.
authors.forename: Sílvio J
authors.initials: SJ
authors.lastname: Ramos
authors.affiliation: Vale Institute of Technology-Sustainable Development, 955 Boaventura da Silva Street, Nazaré Belém 66055-090, Brazil.
authors.forename: José O
authors.initials: JO
authors.lastname: Siqueira
authors.affiliation: Department of Soil Science, Federal University of Lavras, CP 3037, Campus UFLA, Lavras 37200-000, Brazil.
authors.forename: Valdemar
authors.initials: V
authors.lastname: Faquin
authors.affiliation: Department of Biology, Federal University of Lavras, CP 3037, Campus UFLA, Lavras 37200-000, Brazil.
authors.forename: Evaristo M
authors.initials: EM
authors.lastname: de Castro
authors.affiliation: Department of Soil Science, Federal University of Lavras, CP 3037, Campus UFLA, Lavras 37200-000, Brazil.
authors.forename: Douglas C
authors.initials: DC
authors.lastname: Amaral
authors.affiliation: Department of Biology, Federal University of Lavras, CP 3037, Campus UFLA, Lavras 37200-000, Brazil.
authors.forename: Vânia H
authors.initials: VH
authors.lastname: Techio
authors.affiliation: Department of Soil Science, Federal University of Lavras, CP 3037, Campus UFLA, Lavras 37200-000, Brazil.
authors.forename: Lívia C
authors.initials: LC
authors.lastname: Coelho
authors.affiliation: Department of Soil Science, Federal University of Lavras, CP 3037, Campus UFLA, Lavras 37200-000, Brazil.
authors.forename: Pedro H P
authors.initials: PH
authors.lastname: e Silva
authors.affiliation: Institute for Crop and Soil Science, 38116 Braunschweig, Germany.
authors.forename: Ewald
authors.initials: E
authors.lastname: Schnug
authors.affiliation: Department of Soil Science, Federal University of Lavras, CP 3037, Campus UFLA, Lavras 37200-000, Brazil. Electronic address: guilherm@dcs.ufla.br.
authors.forename: Luiz R G
authors.initials: LR
authors.lastname: Guilherme
mesh_terms: D002473:Cell Wall / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D002734:Chlorophyll / Q000378:metabolism; D002736:Chloroplasts / Q000187:drug effects / Q000648:ultrastructure; D007811:Lanthanum / Q000494:pharmacology*; D008940:Mitotic Index; D010788:Photosynthesis / Q000187:drug effects; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism / Q000648:ultrastructure; D018520:Plant Shoots / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D013025:Glycine max / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D002734:Chlorophyll; D007811:Lanthanum
keywords: Lanthanum; Mitotic index; Photosynthetic rate; Ultrastructural analysis