title: The Liguleless narrow mutation affects proximal-distal signaling and leaf growth.
abstract: How cells acquire competence to differentiate according to position is an essential question in developmental biology. Maize leaves provide a unique opportunity to study positional information. In the developing leaf primordium, a line is drawn across a field of seemingly identical cells. Above the line, the cells become blade, below the line the cells become sheath and at the line, the cells differentiate into the specialized tissues of ligule and auricle. We identified a new mutation, Liguleless narrow (Lgn), that affects this patterning and shows striking defects in lateral growth as well, thus linking proximal-distal patterning to medial-lateral growth. In characterizing the defect we discovered that both the auxin transport protein ZmPIN1a and the squamosa promoter-binding protein LIGULELESS1 are expressed precisely at this positionally cued line and are disrupted by Lgn. Positional cloning and a transposon-derived allele demonstrate that LGN is a kinase. These results suggest that LGN participates in setting up positional information through a signaling cascade. Interestingly, LGN has a paralog that is upregulated in the mutant, suggesting an important feedback mechanism involved in setting the positional boundary.
authors.affiliation: Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA.
authors.forename: Jihyun
authors.initials: J
authors.lastname: Moon
authors.forename: Héctor
authors.initials: H
authors.lastname: Candela
authors.forename: Sarah
authors.initials: S
authors.lastname: Hake
mesh_terms: D000595:Amino Acid Sequence; D020134:Catalytic Domain; D003001:Cloning, Molecular; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D016678:Genome; D017403:In Situ Hybridization; D007210:Indoleacetic Acids / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D018515:Plant Leaves / Q000254:growth & development* / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*; D011401:Promoter Regions, Genetic; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D003313:Zea mays / Q000235:genetics* / Q000378:metabolism
chemical_list: D007210:Indoleacetic Acids; C105241:LG1 protein, Zea mays; D010940:Plant Proteins