title: The Maize PI/GLO Ortholog Zmm16/sterile tassel silky ear1 Interacts with the Zygomorphy and Sex Determination Pathways in Flower Development.
abstract: In monocots and eudicots, B class function specifies second and third whorl floral organ identity as described in the classic ABCE model. Grass B class APETALA3/DEFICIENS orthologs have been functionally characterized; here, we describe the positional cloning and characterization of a maize (Zea mays) PISTILLATA/GLOBOSA ortholog Zea mays mads16 (Zmm16)/sterile tassel silky ear1 (sts1). We show that, similar to many eudicots, all the maize B class proteins bind DNA as obligate heterodimers and positively regulate their own expression. However, sts1 mutants have novel phenotypes that provide insight into two derived aspects of maize flower development: carpel abortion and floral asymmetry. Specifically, we show that carpel abortion acts downstream of organ identity and requires the growth-promoting factor grassy tillers1 and that the maize B class genes are expressed asymmetrically, likely in response to zygomorphy of grass floral primordia. Further investigation reveals that floral phyllotactic patterning is also zygomorphic, suggesting significant mechanistic differences with the well-characterized models of floral polarity. These unexpected results show that despite extensive study of B class gene functions in diverse flowering plants, novel insights can be gained from careful investigation of homeotic mutants outside the core eudicot model species.
authors.affiliation: Department of Biology, Brigham Young University, Provo, Utah 84602.
authors.forename: Madelaine E
authors.initials: ME
authors.lastname: Bartlett
authors.affiliation: Department of Biology, Brigham Young University, Provo, Utah 84602.
authors.forename: Steven K
authors.initials: SK
authors.lastname: Williams
authors.affiliation: Department of Biology, Brigham Young University, Provo, Utah 84602.
authors.forename: Zac
authors.initials: Z
authors.lastname: Taylor
authors.affiliation: Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724.
authors.forename: Stacy
authors.initials: S
authors.lastname: DeBlasio
authors.affiliation: Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724.
authors.forename: Alexander
authors.identifier: http://orcid.org/0000-0001-7468-6779
authors.initials: A
authors.lastname: Goldshmidt
authors.affiliation: Section of Cell and Developmental Biology, University of California San Diego, La Jolla, California 92093-0116.
authors.forename: Darren H
authors.initials: DH
authors.lastname: Hall
authors.affiliation: Section of Cell and Developmental Biology, University of California San Diego, La Jolla, California 92093-0116.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Schmidt
authors.affiliation: Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724.
authors.forename: David P
authors.initials: DP
authors.lastname: Jackson
authors.affiliation: Department of Biology, Brigham Young University, Provo, Utah 84602 whipple@byu.edu.
authors.forename: Clinton J
authors.identifier: http://orcid.org/0000-0001-7879-235X
authors.initials: CJ
authors.lastname: Whipple
mesh_terms: D003001:Cloning, Molecular; D018744:DNA, Plant / Q000378:metabolism; D035264:Flowers / Q000254:growth & development* / Q000378:metabolism* / Q000648:ultrastructure; D018506:Gene Expression Regulation, Plant; D055785:Gene Knockdown Techniques; D017343:Genes, Plant; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D018515:Plant Leaves / Q000502:physiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D055503:Protein Multimerization; D021381:Protein Transport; D034622:RNA Interference; D017386:Sequence Homology, Amino Acid; D003313:Zea mays / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D018744:DNA, Plant; D010940:Plant Proteins