title: Nitrate regulates rhizobial and mycorrhizal symbiosis in common bean (Phaseolus vulgaris L.).
abstract: Nitrogen-limited conditions are considered to be a prerequisite for legume-rhizobial symbiosis, but the effects of nitrate-rich conditions on symbiotic status remain poorly understood. We addressed this issue by examining rhizobial (Rhizobim tropici) and arbusclar mycorrhizal (Glomus intraradices) symbiosis in Phaseolus vulgaris L. cv. Negro Jamapa under nitrate pre-incubation and continuous nitrate conditions. Our results indicate that nitrate pre-incubation, independent of the concentration, did not affect nodule development. However, the continuous supply of nitrate at high concentrations impaired nodule maturation and nodule numbers. Low nitrate conditions, in addition to positively regulating nodule number, biomass, and nitrogenase activity, also extended the span of nitrogen-fixing activity. By contrast, for arbuscular mycorrhizae, continuous 10 and 50 mmol/L nitrate increased the percent root length colonization, concomitantly reduced arbuscule size, and enhanced ammonia transport without affecting phosphate transport. Therefore, in this manuscript, we have proposed the importance of nitrate as a positive regulator in promoting both rhizobial and mycorrhizal symbiosis in the common bean.
authors.affiliation: Genómica Funcional de Eucariotes, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, UNAM, Apartado Postal 510-3, Cuernavaca, Morelos 62271, México; Escuela Nacional de Estudios Superiores-UNAM, León, Blvd.UNAM 2011, Predio El Saucillo y El Potrero, Comunidad de los Tepetates, León, Gto. C.P.37684, Mexico.
authors.forename: Kalpana
authors.initials: K
authors.lastname: Nanjareddy
authors.forename: Lourdes
authors.initials: L
authors.lastname: Blanco
authors.forename: Manoj-Kumar
authors.initials: MK
authors.lastname: Arthikala
authors.forename: Xochitl Alvarado
authors.initials: XA
authors.lastname: Affantrange
authors.forename: Federico
authors.initials: F
authors.lastname: Sánchez
authors.forename: Miguel
authors.initials: M
authors.lastname: Lara
mesh_terms: D064751:Ammonium Compounds / Q000378:metabolism; D018533:Biomass; D048429:Cell Size / Q000187:drug effects; D015169:Colony Count, Microbial; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D038821:Mycorrhizae / Q000187:drug effects / Q000502:physiology*; D009566:Nitrates / Q000494:pharmacology*; D009586:Nitrogen Fixation / Q000187:drug effects / Q000235:genetics; D009591:Nitrogenase / Q000378:metabolism; D027805:Phaseolus / Q000187:drug effects / Q000235:genetics / Q000382:microbiology* / Q000502:physiology*; D010641:Phenotype; D010758:Phosphorus / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018520:Plant Shoots / Q000187:drug effects / Q000254:growth & development; D012231:Rhizobium / Q000187:drug effects / Q000254:growth & development / Q000502:physiology*; D053204:Root Nodules, Plant / Q000187:drug effects / Q000502:physiology; D013559:Symbiosis / Q000187:drug effects* / Q000235:genetics
chemical_list: D064751:Ammonium Compounds; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D009566:Nitrates; D010940:Plant Proteins; C045625:nodulin; D010758:Phosphorus; D009591:Nitrogenase
keywords: Arbuscule; Rhizobium; common bean; mycorrhiza; nitrate; nodule