title: The CCAAT box-binding transcription factor NF-YA1 controls rhizobial infection.
abstract: Symbiosis between legume plants and soil rhizobia culminates in the formation of a novel root organ, the 'nodule', containing bacteria differentiated as facultative nitrogen-fixing organelles. MtNF-YA1 is a Medicago truncatula CCAAT box-binding transcription factor (TF), formerly called HAP2-1, highly expressed in mature nodules and required for nodule meristem function and persistence. Here a role for MtNF-YA1 during early nodule development is demonstrated. Detailed expression analysis based on RNA sequencing, quantitiative real-time PCR (qRT-PCR), as well as promoter-β-glucuronidase (GUS) fusions reveal that MtNF-YA1 is first induced at the onset of symbiotic development during preparation for, and initiation and progression of, symbiotic infection. Moreover, using a new knock-out mutant, Mtnf-ya1-1, it is shown that MtNF-YA1 controls infection thread (IT) progression from initial root infection through colonization of nodule tissues. Extensive confocal and electronic microscopic observations suggest that the bulbous and erratic IT growth phenotypes observed in Mtnf-ya1-1 could be a consequence of the fact that walls of ITs in this mutant are thinner and less coherent than in the wild type. It is proposed that MtNF-YA1 controls rhizobial infection progression by regulating the formation and the wall of ITs.
authors: INRA, Laboratoire des Interactions Plantes-Microorganismes (LIPM), UMR441, Castanet-Tolosan, F-31326, France.
authors: Philippe
authors: P
authors: Laporte
authors: Agnes
authors: A
authors: Lepage
authors: Joëlle
authors: J
authors: Fournier
authors: Olivier
authors: O
authors: Catrice
authors: Sandra
authors: S
authors: Moreau
authors: Marie-Françoise
authors: MF
authors: Jardinaud
authors: Jeong-Hwan
authors: JH
authors: Mun
authors: Estibaliz
authors: E
authors: Larrainzar
authors: Douglas R
authors: DR
authors: Cook
authors: Pascal
authors: P
authors: Gamas
authors: Andreas
authors: A
authors: Niebel
mesh_terms: D001483:Base Sequence; D018506:Gene Expression Regulation, Plant; D005816:Genetic Complementation Test; D046913:Medicago truncatula / Q000235:genetics / Q000382:microbiology*; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D053204:Root Nodules, Plant / Q000254:growth & development / Q000382:microbiology / Q000648:ultrastructure; D016962:Sinorhizobium meliloti / Q000502:physiology*; D013559:Symbiosis / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; D014157:Transcription Factors
keywords: CCAAT box-binding factor; Medicago truncatula; NF-YA; infection; infection thread; nodule development; rhizobium; symbiosis.