Restoration of DWF4 expression to the leaf margin of a dwf4 mutant is sufficient to restore leaf shape but not size: the role of the margin in leaf development.
The role of the margin in leaf development has been debated over a number of years. To investigate the molecular basis of events in the margin, we performed an enhancer trap screen to identify genes specifically expressed in this tissue. Analysis of one of these lines revealed abnormal differentiation in the margin, accompanied by an abnormal leaf size and shape. Further analysis revealed that this phenotype was due to insertion of the trap into DWF4, which encodes a key enzyme in brassinolide biosynthesis. Transcripts for this gene accumulated in a specific and dynamic pattern in the epidermis of young leaf primordia. Targeted expression of DWF4 to a subset of these cells (the leaf margin) in a dwf4 mutant background led to both restoration of differentiation of a specific group of leaf cells (margin cells) and restoration of wild-type leaf shape (but not leaf size). Ablation of these cells led to abrogation of leaf development and the formation of small round leaves. These data support the hypothesis that events in the margin play an essential role in leaf morphogenesis, and implicate brassinolide in the margin as a key mediator in the control of leaf shape, separable from a general function of this growth factor in the control of organ size.
Reinhardt
Beate
B
Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield S10 2TN, UK.
Hänggi
Emanuel
E
Müller
Sabrine
S
Bauch
Marion
M
Wyrzykowska
Joanna
J
Kerstetter
Randall
R
Poethig
Scott
S
Fleming
Andrew J
AJ
D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000648:ultrastructure; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000502:physiology; D060406:Brassinosteroids; D002777:Cholestanols / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics* / Q000502:physiology; D018506:Gene Expression Regulation, Plant; D017403:In Situ Hybridization; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D010641:Phenotype; D018515:Plant Leaves / Q000235:genetics* / Q000254:growth & development / Q000648:ultrastructure; D030821:Plants, Genetically Modified; D020133:Reverse Transcriptase Polymerase Chain Reaction; D036226:Seedlings / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D013260:Steroids, Heterocyclic / Q000378:metabolism
C111451:AT3G50660 protein, Arabidopsis; D029681:Arabidopsis Proteins; D060406:Brassinosteroids; D002777:Cholestanols; D013260:Steroids, Heterocyclic; D003577:Cytochrome P-450 Enzyme System; C023623:brassinolide