title: Nitrogen compounds in the apoplastic sap of sugarcane stem: some implications in the association with endophytes.
abstract: Several nitrogen compounds were identified and quantified in the apoplastic and symplastic sap of sugarcane stems. The sap of stems was composed mainly of soluble sugars, which constituted 95% of the total organic compounds detected. Sap also contained nitrogen compounds, with amino acids (50-70% of N) and proteins (20-30% of N), being the main nitrogenous substances, as well as inorganic forms as ammonium, nitrite and nitrate, in low concentrations (<20% of N). Serine, proline, alanine and aspartic acid together represented around 60% of the amino acids of the sap of both field grown and high nitrogen fertilized plants, and non-nitrogen fertilized plants inoculated with Gluconacetobacter diazotrophicus. The total amino acid content of apoplastic sap was six to nine times lower in non-nitrogen fertilized plants than in fertilized ones. The possible roles of these substances to regulate endophytic associations with sugarcane are also discussed.
authors.affiliation: Facultad de Ciencias, Departamento de Fisiología Vegetal, Universidad de Granada, Campus de Fuentenueva s/n, Spain. natejera@ugr.es
authors.forename: Noel
authors.initials: N
authors.lastname: Tejera
authors.forename: Eduardo
authors.initials: E
authors.lastname: Ortega
authors.forename: Rosa
authors.initials: R
authors.lastname: Rodes
authors.forename: Carmen
authors.initials: C
authors.lastname: Lluch
mesh_terms: D041821:Gluconacetobacter / Q000502:physiology; D017672:Nitrogen Compounds / Q000032:analysis*; D009586:Nitrogen Fixation; D018547:Plant Stems / Q000737:chemistry* / Q000382:microbiology; D031786:Saccharum / Q000737:chemistry* / Q000382:microbiology; D013559:Symbiosis
chemical_list: D017672:Nitrogen Compounds