title: Structural and metabolic transitions of C4 leaf development and differentiation defined by microscopy and quantitative proteomics in maize.
abstract: C(4) grasses, such as maize (Zea mays), have high photosynthetic efficiency through combined biochemical and structural adaptations. C(4) photosynthesis is established along the developmental axis of the leaf blade, leading from an undifferentiated leaf base just above the ligule into highly specialized mesophyll cells (MCs) and bundle sheath cells (BSCs) at the tip. To resolve the kinetics of maize leaf development and C(4) differentiation and to obtain a systems-level understanding of maize leaf formation, the accumulation profiles of proteomes of the leaf and the isolated BSCs with their vascular bundle along the developmental gradient were determined using large-scale mass spectrometry. This was complemented by extensive qualitative and quantitative microscopy analysis of structural features (e.g., Kranz anatomy, plasmodesmata, cell wall, and organelles). More than 4300 proteins were identified and functionally annotated. Developmental protein accumulation profiles and hierarchical cluster analysis then determined the kinetics of organelle biogenesis, formation of cellular structures, metabolism, and coexpression patterns. Two main expression clusters were observed, each divided in subclusters, suggesting that a limited number of developmental regulatory networks organize concerted protein accumulation along the leaf gradient. The coexpression with BSC and MC markers provided strong candidates for further analysis of C(4) specialization, in particular transporters and biogenesis factors. Based on the integrated information, we describe five developmental transitions that provide a conceptual and practical template for further analysis. An online protein expression viewer is provided through the Plant Proteome Database.
authors.affiliation: Department of Plant Biology, Cornell University, Ithaca, New York 14853, USA.
authors.forename: Wojciech
authors.initials: W
authors.lastname: Majeran
authors.forename: Giulia
authors.initials: G
authors.lastname: Friso
authors.forename: Lalit
authors.initials: L
authors.lastname: Ponnala
authors.forename: Brian
authors.initials: B
authors.lastname: Connolly
authors.forename: Mingshu
authors.initials: M
authors.lastname: Huang
authors.forename: Edwin
authors.initials: E
authors.lastname: Reidel
authors.forename: Cankui
authors.initials: C
authors.lastname: Zhang
authors.forename: Yukari
authors.initials: Y
authors.lastname: Asakura
authors.forename: Nazmul H
authors.initials: NH
authors.lastname: Bhuiyan
authors.forename: Qi
authors.initials: Q
authors.lastname: Sun
authors.forename: Robert
authors.initials: R
authors.lastname: Turgeon
authors.forename: Klaas J
authors.initials: KJ
authors.lastname: van Wijk
mesh_terms: D002244:Carbon / Q000378:metabolism*; D002454:Cell Differentiation / Q000502:physiology*; D002473:Cell Wall / Q000378:metabolism; D002736:Chloroplasts / Q000378:metabolism; D030562:Databases, Protein; D017343:Genes, Plant; D006706:Homeostasis; D058503:Mesophyll Cells / Q000166:cytology / Q000502:physiology; D008928:Mitochondria / Q000378:metabolism; D005810:Multigene Family; D010084:Oxidation-Reduction; D010788:Photosynthesis / Q000502:physiology; D018515:Plant Leaves / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D040901:Proteomics / Q000379:methods*; D017382:Reactive Oxygen Species / Q000378:metabolism; D015203:Reproducibility of Results; D013729:Terpenes / Q000378:metabolism; D003313:Zea mays / Q000033:anatomy & histology / Q000254:growth & development / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D017382:Reactive Oxygen Species; D013729:Terpenes; D002244:Carbon