title: Maize early endosperm growth and development: from fertilization through cell type differentiation.
abstract: •
  
  
  OBJECTIVE
  Given the worldwide economic importance of maize endosperm, it is surprising that its development is not the most comprehensively studied of the cereals. We present detailed morphometric and cytological descriptions of endosperm development in the maize inbred line B73, for which the genome has been sequenced, and compare its growth with four diverse Nested Association Mapping (NAM) founder lines.•
  
  
  METHODS
  The first 12 d of B73 endosperm development were described using semithin sections of plastic-embedded kernels and confocal microscopy. Longitudinal sections were used to compare endosperm length, thickness, and area.•
  
  
  RESULTS
  Morphometric comparison between Arizona- and Michigan-grown B73 showed a common pattern. Early endosperm development was divided into four stages: coenocytic, cellularization through alveolation, cellularization through partitioning, and differentiation. We observed tightly synchronous nuclear divisions in the coenocyte, elucidated that the onset of cellularization was coincident with endosperm size, and identified a previously undefined cell type (basal intermediate zone, BIZ). NAM founders with small mature kernels had larger endosperms (0-6 d after pollination) than lines with large mature kernels.•
  
  
  CONCLUSIONS
  Our B73-specific model of early endosperm growth links developmental events to relative endosperm size, while accounting for diverse growing conditions. Maize endosperm cellularizes through alveolation, then random partitioning of the central vacuole. This unique cellularization feature of maize contrasts with the smaller endosperms of Arabidopsis, barley, and rice that strictly cellularize through repeated alveolation. NAM analysis revealed differences in endosperm size during early development, which potentially relates to differences in timing of cellularization across diverse lines of maize.
authors.affiliation: Department of Biology, Central Michigan University, Mount Pleasant, Michigan 48859 USA.
authors.forename: Brian M
authors.initials: BM
authors.lastname: Leroux
authors.affiliation: Department of Biology, Central Michigan University, Mount Pleasant, Michigan 48859 USA.
authors.forename: Austin J
authors.initials: AJ
authors.lastname: Goodyke
authors.affiliation: Department of Biology, Central Michigan University, Mount Pleasant, Michigan 48859 USA.
authors.forename: Katelyn I
authors.initials: KI
authors.lastname: Schumacher
authors.affiliation: Department of Biology, Central Michigan University, Mount Pleasant, Michigan 48859 USA.
authors.forename: Chelsi P
authors.initials: CP
authors.lastname: Abbott
authors.affiliation: Division of Natural Sciences, New College of Florida, Sarasota, Florida 34243 USA.
authors.forename: Amy M
authors.initials: AM
authors.lastname: Clore
authors.affiliation: School of Plant Sciences, University of Arizona, Tucson, Arizona 85721 USA.
authors.forename: Ramin
authors.initials: R
authors.lastname: Yadegari
authors.affiliation: School of Plant Sciences, University of Arizona, Tucson, Arizona 85721 USA.
authors.forename: Brian A
authors.initials: BA
authors.lastname: Larkins
authors.affiliation: Department of Biology, Central Michigan University, Mount Pleasant, Michigan 48859 USA.
authors.forename: Joanne M
authors.initials: JM
authors.lastname: Dannenhoffer
mesh_terms: D002454:Cell Differentiation; D056625:Endosperm / Q000033:anatomy & histology / Q000166:cytology / Q000254:growth & development*; D005306:Fertilization; D059828:Plant Cells; D054817:Pollination; D013045:Species Specificity; D003313:Zea mays / Q000033:anatomy & histology / Q000166:cytology / Q000254:growth & development*
keywords: B73 maize; BETL; NAM; Poaceae; alveolation; cellularization; cereals; coenocyte; differentiation; nuclear endosperm