title: NO APICAL MERISTEM (MtNAM) regulates floral organ identity and lateral organ separation in Medicago truncatula.
abstract: • The CUP-SHAPED COTYLEDON (CUC)/NO APICAL MERISTEM (NAM) family of genes control boundary formation and lateral organ separation, which is critical for proper leaf and flower patterning. However, most downstream targets of CUC/NAM genes remain unclear. • In a forward screen of the tobacco retrotransposon1 (Tnt1) insertion population in Medicago truncatula, we isolated a weak allele of the no-apical-meristem mutant mtnam-2. Meanwhile, we regenerated a mature plant from the null allele mtnam-1. These materials allowed us to extensively characterize the function of MtNAM and its downstream genes. • MtNAM is highly expressed in vegetative shoot buds and inflorescence apices, specifically at boundaries between the shoot apical meristem and leaf/flower primordia. Mature plants of the regenerated null allele and the weak allele display remarkable floral phenotypes: floral whorls and organ numbers are reduced and the floral organ identity is compromised. Microarray and quantitative RT-PCR analyses revealed that all classes of floral homeotic genes are down-regulated in mtnam mutants. Mutations in MtNAM also lead to fused cotyledons and leaflets of the compound leaf as well as a defective shoot apical meristem. • Our results revealed that MtNAM shares the role of CUC/NAM family genes in lateral organ separation and compound leaf development, and is also required for floral organ identity and development.
authors.affiliation: Plant Biology Division, Samuel Roberts Noble Foundation, Ardmore, OK 73401, USA.
authors.forename: Xiaofei
authors.initials: X
authors.lastname: Cheng
authors.forename: Jianling
authors.initials: J
authors.lastname: Peng
authors.forename: Junying
authors.initials: J
authors.lastname: Ma
authors.forename: Yuhong
authors.initials: Y
authors.lastname: Tang
authors.forename: Rujin
authors.initials: R
authors.lastname: Chen
authors.forename: Kirankumar S
authors.initials: KS
authors.lastname: Mysore
authors.forename: Jiangqi
authors.initials: J
authors.lastname: Wen
mesh_terms: D018548:Cotyledon / Q000033:anatomy & histology / Q000235:genetics; D035264:Flowers / Q000235:genetics / Q000502:physiology*; D018506:Gene Expression Regulation, Plant; D056726:Genetic Association Studies; D056626:Inflorescence / Q000033:anatomy & histology / Q000235:genetics; D046913:Medicago truncatula / Q000235:genetics / Q000502:physiology*; D018519:Meristem / Q000235:genetics* / Q000502:physiology; D008969:Molecular Sequence Data; D009154:Mutation; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism*; D018626:Retroelements
chemical_list: D010940:Plant Proteins; D018626:Retroelements