title: Seeds' physicochemical traits and mucilage protection against aluminum effect during germination and root elongation as important factors in a biofuel seed crop (Ricinus communis).
abstract: We determined the length, volume, dry biomass, and density in seeds of five castor bean cultivars and verified notable physicochemical trait differences. Seeds were then subjected to different toxic aluminum (Al) concentrations to evaluate germination, relative root elongation, and the role of root apices' rhizosphere mucilage layer. Seeds' physicochemical traits were associated with Al toxicity responses, and the absence of Al in cotyledons near to the embryo was revealed by Al-hematoxylin staining, indicating that Al did not induce significant germination reduction rates between cultivars. However, in the more sensitive cultivar, Al was found around the embryo, contributing to subsequent growth inhibition. After this, to investigate the role of mucilage in Al tolerance, an assay was conducted using NH4Cl to remove root mucilage before or after exposure to different Al concentrations. Sequentially, the roots were stained with hematoxylin and a quantitative analysis of staining intensity was obtained. These results revealed the significant contribution of the mucilage layer to Al toxicity responses in castor bean seedlings. Root growth elongation under Al toxicity confirmed the role of the mucilage layer, which jointly indicated the differential Al tolerance between cultivars and an efficient Al-exclusion mechanism in the tolerant cultivar.
authors.affiliation: Plant Physiology Laboratory, Biological Science Institute, Federal University of Minas Gerais, Av. Antônio Carlos, 6627, Pampulha, Belo Horizonte, MG, 31.270-901, Brazil.
authors.forename: Giovanni Eustáquio Alves
authors.initials: GE
authors.lastname: Silva
authors.forename: Flávia Toledo
authors.initials: FT
authors.lastname: Ramos
authors.forename: Ana Paula
authors.initials: AP
authors.lastname: de Faria
authors.forename: Marcel Giovanni Costa
authors.initials: MG
authors.lastname: França
mesh_terms: D000535:Aluminum / Q000378:metabolism / Q000494:pharmacology*; D056804:Biofuels; D002367:Ricinus communis / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism; D010641:Phenotype; D062087:Plant Mucilage / Q000502:physiology*; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D027343:Rhizome / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D036226:Seedlings / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D012639:Seeds / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism; D012989:Soil Pollutants / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D056804:Biofuels; D062087:Plant Mucilage; D012989:Soil Pollutants; D000535:Aluminum