title: Morphoanatomical responses induced by excess iron in roots of two tolerant grass species.
abstract: We aimed to verify whether morphoanatomic alterations occur in response to excess iron, in roots of Setaria parviflora and Paspallum urvillei (Poaceae), and to localize the presence of the sites of iron accumulation. Plants were subjected to 0.009, 1, 2, 4, and 7 mM Fe-EDTA in nutrient solution. Both species presented iron contents in the roots above the critical toxicity level. The presence of iron plaque on roots of the two species was confirmed, and it may have reduced iron absorption by the plants. Roots from the two species showed typical visual symptoms of stress by excess iron: change in color and mucilaginous and flaccid appearance. Anatomical damage was observed in both species: aerenchyma disruption, alterations in endodermal cells, and irregular shape of both vessel and sieve tube elements. The metal was histolocalized in the cortex and in protoxylem and metaxylem cell walls in both species, which suggests a detoxification strategy for the excess iron. Phenolic compounds were not histolocalized in roots. Microscopic analyses were therefore effective in evaluating the real damage caused by excess iron.
authors.affiliation: Universidade Federal de Viçosa, 36570-900, Viçosa, MG, Brazil.
authors.forename: Talita Oliveira
authors.initials: TO
authors.lastname: de Araújo
authors.forename: Larisse
authors.initials: L
authors.lastname: de Freitas-Silva
authors.forename: Brenda Vila Nova
authors.initials: BV
authors.lastname: Santana
authors.forename: Kacilda Naomi
authors.initials: KN
authors.lastname: Kuki
authors.forename: Eduardo Gusmão
authors.initials: EG
authors.lastname: Pereira
authors.forename: Aristéa Alves
authors.initials: AA
authors.lastname: Azevedo
authors.forename: Luzimar Campos
authors.initials: LC
authors.lastname: da Silva
mesh_terms: D002473:Cell Wall / Q000378:metabolism; D007501:Iron / Q000378:metabolism / Q000633:toxicity*; D008670:Metals; D008855:Microscopy, Electron, Scanning; D031781:Paspalum / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D018517:Plant Roots / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D010944:Plants; D006109:Poaceae; D032983:Setaria Plant / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D008670:Metals; D007501:Iron