title: Spatiotemporal features of microsporogenesis in the cycad species Macrozamia communis.
abstract: •
  
  
  OBJECTIVE
  Spatiotemporal features of microsporogenesis may provide important clues about the evolution of microsporogenesis in seed plants. One cellular feature that attracts special attention is advance cell wall ingrowths (ACWIs) at future cytokinetic sites in microsporocytes since they have been found only in species of an ancient lineage of angiosperms, Magnolia, and in much less detail, of an ancient lineage of gymnosperms, cycads. Further investigation into microsporogenesis in a cycad species may yield knowledge critical to understanding the establishment of ACWIs as an important feature for comparative studies of microsporogenesis in seed plants.•
  
  
  METHODS
  Bright-field and epifluorescence microscopy, confocal laser scanning microscopy, and transmission electron microscopy were used to investigate the microsporogenic process in Macrozamia communis, a species in the Zamiaceae family of cycads.•
  
  
  RESULTS
  In prophase-II microsporocytes in M. communis, ACWIs form as a callose ring between the newly formed nuclei and are not accompanied by cytokinetic apparatuses such as mini-phragmoplasts, wide tubules, or wide tubular networks. Shortly after the second nuclear division, new ACWIs, albeit thinner than the previous ACWIs, form between the newly formed nuclei. Subsequent cell plate formation in the planes of the ACWIs typically results in tetragonal tetrads.•
  
  
  CONCLUSIONS
  Cytokinesis at the cell periphery is initiated earlier than cell plate formation in the cell interior in microsporogenesis in M. communis. The cellular features uncovered in M. communis may serve as useful reference features for comparative studies of microsporogenesis in plants.
authors.affiliation: State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangzhou 510642, China.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Yan
authors.affiliation: State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangzhou 510642, China.
authors.forename: Mei
authors.initials: M
authors.lastname: Bai
authors.affiliation: State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangzhou 510642, China.
authors.forename: Xiping
authors.initials: X
authors.lastname: Ning
authors.affiliation: Fujian Institute of Subtropical Botany, Xiamen 361006, China.
authors.forename: Haibo
authors.initials: H
authors.lastname: Ouyang
authors.affiliation: Shenzhen Fairylake Botanical Garden, Shenzhen 518004, China.
authors.forename: Shouzhou
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Department of Botany, Oklahoma State University, 301 Physical Sciences, Stillwater, Oklahoma 74078 USA.
authors.forename: Ming
authors.initials: M
authors.lastname: Yang
authors.affiliation: State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangzhou 510642, China Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, Guangzhou 510642, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Wu
mesh_terms: D005075:Biological Evolution; D002473:Cell Wall / Q000378:metabolism / Q000648:ultrastructure; D048749:Cytokinesis; D056130:Gametogenesis, Plant; D055993:Germ Cells, Plant / Q000502:physiology / Q000648:ultrastructure; D005936:Glucans / Q000378:metabolism; D012639:Seeds / Q000502:physiology* / Q000648:ultrastructure; D062211:Spatio-Temporal Analysis; D032481:Zamiaceae / Q000502:physiology* / Q000648:ultrastructure
chemical_list: D005936:Glucans; C048306:callose
keywords: Macrozamia communis; Magnolia; Zamiaceae; callose; cycads; cytokinesis; evolution; microsporogenesis; seed plants