title: Germination of salt-stressed seeds as related to the ethylene biosynthesis ability in three Stylosanthes species.
abstract: Stylosanthes, a genus of tropical forage legume, is known to exhibit good persistence in saline soils, yet mechanisms for regulation of seed germination under salt stress are poorly understood. This study was carried out to evaluate the mode of action of salt stress on seed germination of Stylosanthes. 1-Aminocyclopropane-1-carboxylic acid (ACC) increased ethylene biosynthesis and germination of NaCl-inhibited seeds in a dose-dependent manner. Contents of ACC and germination of Stylosanthes humilis seeds increased following transfer from NaCl solution to deionised water, but not after transfer to l-α-(2-aminoethoxyvinyl)-glycine (AVG) solution, an inhibitor of ethylene biosynthesis. Ethylene biosynthesis was much larger in NaCl-treated seeds of Stylosanthes guianensis than in seeds of S. humilis and Stylosanthes capitata, a fact which was reflected in higher germination rates. S. guianensis seedlings also displayed higher growth and survival rates than S. humilis and S. capitata under salt stress. Moreover, smaller ACC levels, as well as reduced ethylene biosynthesis of S. capitata seeds were accompanied by lower germination under salt stress. In addition, S. capitata seedlings treated with NaCl solutions exhibited relatively lower growth and survival rates in comparison with S. humilis and S. guianensis. Thus, different abilities to synthesize ethylene by S. guianensis, S. humilis and S. capitata seeds explain the differences in tolerance to salt stress of the three species.
authors.affiliation: Departamento de Biologia Vegetal, Universidade Federal de Viçosa, 36570-000 Viçosa, MG, Brazil.
authors.forename: Priscila O
authors.initials: PO
authors.lastname: Silva
authors.forename: Eduardo F
authors.initials: EF
authors.lastname: Medina
authors.forename: Raimundo S
authors.initials: RS
authors.lastname: Barros
authors.forename: Dimas M
authors.initials: DM
authors.lastname: Ribeiro
mesh_terms: D000598:Amino Acids, Cyclic / Q000032:analysis / Q000494:pharmacology*; D000613:Aminobutyrates / Q000494:pharmacology; D005030:Ethylenes / Q000032:analysis / Q000378:metabolism*; D007887:Fabaceae / Q000187:drug effects / Q000254:growth & development / Q000502:physiology*; D018525:Germination / Q000187:drug effects; D018546:Hypocotyl / Q000187:drug effects / Q000254:growth & development / Q000502:physiology; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development / Q000502:physiology; D055049:Salt Tolerance; D036226:Seedlings / Q000187:drug effects / Q000254:growth & development / Q000502:physiology; D012639:Seeds / Q000187:drug effects / Q000254:growth & development / Q000502:physiology; D012965:Sodium Chloride / Q000032:analysis / Q000494:pharmacology; D013045:Species Specificity
chemical_list: D000598:Amino Acids, Cyclic; D000613:Aminobutyrates; D005030:Ethylenes; C023863:1-aminocyclopropane-1-carboxylic acid; D012965:Sodium Chloride; C012175:2-amino-4-(2-aminoethoxy)butanoic acid; C036216:ethylene
keywords: 1-Aminocyclopropane-1-carboxylic acid; 1-aminocyclopropane-1-carboxylic acid; ACC; AVG; Ethylene; PEG; Salt stress; Seed germination; Stylosanthes; l-α-(2-aminoethoxyvinyl)-glycine; polyethylene glycol-6000