title: PvRACK1 loss-of-function impairs cell expansion and morphogenesis in Phaseolus vulgaris L. root nodules.
abstract: Receptor for activated C kinase (RACK1) is a highly conserved, eukaryotic protein of the WD-40 repeat family. Its peculiar β-propeller structure allows its interaction with multiple proteins in various plant signal-transduction pathways, including those arising from hormone responses, development, and environmental stress. During Phaseolus vulgaris root development, RACK1 (PvRACK1) mRNA expression was induced by auxins, abscissic acid, cytokinin, and gibberellic acid. In addition, during P. vulgaris nodule development, PvRACK1 mRNA was highly accumulated at 12 to 15 days postinoculation, suggesting an important role after nodule meristem initiation and Rhizobium nodule infection. PvRACK1 transcript accumulation was downregulated by a specific RNA interference construct which was expressed in transgenic roots of composite plants of P. vulgaris inoculated with Rhizobium tropici. PvRACK1 downregulated transcript levels were monitored by quantitative reverse-transcription polymerase chain reaction analysis in individual transgenic roots and nodules. We observed a clear phenotype in PvRACK1-knockdown nodules, in which nodule number and nodule cell expansion were impaired, resulting in altered nodule size. Microscopic analysis indicated that, in PvRACK1-knockdown nodules, infected and uninfected cells were considerably smaller (80 and 60%, respectively) than in control nodules. In addition, noninfected cells and symbiosomes in silenced nodules showed significant defects in membrane structure under electron microscopy analysis. These findings indicate that PvRACK1 has a pivotal role in cell expansion and in symbiosome and bacteroid integrity during nodule development.
authors.affiliation: Departamento de Biologia Molecular de Plantas, Universidad Nacional Autonoma de Mexico, Morelos, Mexico.
authors.forename: Tania
authors.initials: T
authors.lastname: Islas-Flores
authors.forename: Gabriel
authors.initials: G
authors.lastname: Guillén
authors.forename: Xóchitl
authors.initials: X
authors.lastname: Alvarado-Affantranger
authors.forename: Miguel
authors.initials: M
authors.lastname: Lara-Flores
authors.forename: Federico
authors.initials: F
authors.lastname: Sánchez
authors.forename: Marco A
authors.initials: MA
authors.lastname: Villanueva
mesh_terms: D002462:Cell Membrane / Q000648:ultrastructure; D049109:Cell Proliferation; D018506:Gene Expression Regulation, Plant; D055785:Gene Knockdown Techniques; D009024:Morphogenesis; D027805:Phaseolus / Q000235:genetics / Q000254:growth & development / Q000382:microbiology / Q000502:physiology*; D010641:Phenotype; D010937:Plant Growth Regulators / Q000494:pharmacology; D055170:Plant Root Nodulation / Q000235:genetics*; D018517:Plant Roots / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D030821:Plants, Genetically Modified; D011493:Protein Kinase C / Q000378:metabolism; D034622:RNA Interference; D012333:RNA, Messenger / Q000235:genetics; D018749:RNA, Plant / Q000235:genetics; D000075370:Receptors for Activated C Kinase; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D042162:Rhizobium tropici / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D053204:Root Nodules, Plant / Q000254:growth & development / Q000382:microbiology; D015398:Signal Transduction
chemical_list: D010937:Plant Growth Regulators; D012333:RNA, Messenger; D018749:RNA, Plant; D000075370:Receptors for Activated C Kinase; D011956:Receptors, Cell Surface; D011493:Protein Kinase C