title: 24-Epibrassinolide ameliorates salt stress effects in the symbiosis Medicago truncatula-Sinorhizobium meliloti and regulates the nodulation in cross-talk with polyamines.
abstract: Brassinosteroids (BRs) are steroid plant hormones that have been shown to be involved in the response to salt stress in cross-talk with other plant growth regulators such as polyamines (PAs). In addition, BRs are involved in the regulation of the nodulation in the rhizobium-legume symbiosis through the alteration of the PAs content in leaves. In this work, we have studied the effect of exogenous 24-epibrassinolide (EBL) in the response to salinity of nitrogen fixation in the symbiosis Medicago truncatula-Sinorhizobium meliloti. Foliar spraying of EBL restored the growth of plants subjected to salt stress and provoked an increment of the nitrogenase activity. In general, PAs levels in leaves and nodules decreased by the salt and EBL treatments, however, the co-treatment with NaCl and EBL augmented the foliar spermine (Spm) concentration. This increment of the Spm levels was followed by a reduction of the membrane oxidative damage and a diminution of the proline accumulation. The effect of BRs on the symbiotic interaction was evaluated by the addition of 0.01, 0.1 and 0.5 μM EBL to the growing solution, which provoked a reduction of the nodule number and an increment of the PAs levels in shoot. In conclusion, foliar treatment with EBL had a protective effect against salt stress in the M. truncatula-S. meliloti symbiosis mediated by an increment of the Spm levels. Treatment of roots with EBL incremented PAs levels in shoot and reduced the nodule number which suggests a cross-talk between PAs and BRs in the nodule suppression and the protection against salt stress.
authors.affiliation: Departamento de Fisiología Vegetal, Facultad de Ciencias, Universidad de Granada, Campus de Fuentenueva s/n, 18071, Granada, Spain. Electronic address: mlgomez@ugr.es.
authors.forename: Miguel
authors.initials: M
authors.lastname: López-Gómez
authors.affiliation: Departamento de Fisiología Vegetal, Facultad de Ciencias, Universidad de Granada, Campus de Fuentenueva s/n, 18071, Granada, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Hidalgo-Castellanos
authors.affiliation: Departamento de Fisiología Vegetal, Facultad de Ciencias, Universidad de Granada, Campus de Fuentenueva s/n, 18071, Granada, Spain.
authors.forename: Carmen
authors.initials: C
authors.lastname: Lluch
authors.affiliation: Departamento de Fisiología Vegetal, Facultad de Ciencias, Universidad de Granada, Campus de Fuentenueva s/n, 18071, Granada, Spain.
authors.forename: José A
authors.initials: JA
authors.lastname: Herrera-Cervera
mesh_terms: D060406:Brassinosteroids / Q000008:administration & dosage / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D018506:Gene Expression Regulation, Plant; D015227:Lipid Peroxidation / Q000187:drug effects; D046913:Medicago truncatula / Q000187:drug effects* / Q000382:microbiology* / Q000502:physiology; D009586:Nitrogen Fixation / Q000187:drug effects / Q000502:physiology; D010937:Plant Growth Regulators / Q000494:pharmacology; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000382:microbiology; D018520:Plant Shoots / Q000378:metabolism; D011073:Polyamines / Q000378:metabolism; D011392:Proline / Q000378:metabolism; D053204:Root Nodules, Plant / Q000187:drug effects / Q000378:metabolism / Q000382:microbiology; D055049:Salt Tolerance / Q000187:drug effects; D016962:Sinorhizobium meliloti / Q000187:drug effects* / Q000502:physiology; D013260:Steroids, Heterocyclic / Q000008:administration & dosage / Q000494:pharmacology*; D013312:Stress, Physiological / Q000187:drug effects; D013559:Symbiosis / Q000187:drug effects
chemical_list: D060406:Brassinosteroids; D010937:Plant Growth Regulators; D011073:Polyamines; D013260:Steroids, Heterocyclic; D011392:Proline; C023623:brassinolide
keywords: 24-Epibrassinolide; Brassinosteroids; Medicago truncatula; Polyamines; Salt stress; Symbiosis