Abstract
A key challenge in biology is to understand how the regional control of cell growth gives rise to final organ forms. Plant leaves must coordinate growth along both the proximodistal and mediolateral axes to produce their final shape. However, the cell-level mechanisms controlling this coordination remain largely unclear. Here, we show that, in A.thaliana, WOX5, one of the WUSCHEL-RELATED HOMEOBOX (WOX) family of homeobox genes, acts redundantly with WOX1 and WOX3 (PRESSED FLOWER [PRS]) to control leaf shape. Through genetics and hormone measurements, we find that these WOXs act in part through the regional control of YUCCA (YUC) auxin biosynthetic gene expression along the leaf margin. The requirement for WOX-mediated YUC expression in patterning of leaf shape cannot be bypassed by the epidermal expression of YUC, indicating that the precise domain of auxin biosynthesis is important for leaf form. Using time-lapse growth analysis, we demonstrate that WOX-mediated auxin biosynthesis organizes a proximodistal growth gradient that promotes lateral growth and consequently the characteristic ellipsoid A.thaliana leaf shape. We also provide evidence that WOX proteins shape the proximodistal gradient of differentiation by inhibiting differentiation proximally in the leaf blade and promoting it distally. This regulation allows sustained growth of the blade and enables a leaf to attain its final form. In conclusion, we show that the WOX/auxin regulatory module shapes leaf form by coordinating growth along the proximodistal and mediolateral leaf axes.
Highlights
How gene activity translates into distinct organ morphologies in complex eukaryotes remains poorly understood [1, 2]
Through genetics and hormone measurements, we find that these WUSCHEL-RELATED HOMEOBOX (WOX) act in part through the regional control of YUCCA (YUC) auxin biosynthetic gene expression along the leaf margin
The requirement for WOXmediated YUC expression in patterning of leaf shape cannot be bypassed by the epidermal expression of YUC, indicating that the precise domain of auxin biosynthesis is important for leaf form
Summary
How gene activity translates into distinct organ morphologies in complex eukaryotes remains poorly understood [1, 2] Resolving this problem requires us to characterize the genetic modules that control different aspects of form and to understand how they influence the amount, direction, and duration of growth to shape final organ geometry [3]. Theoretical models derived from time-lapse imaging indicate that a basally emanating morphogen may shape A. thaliana leaf form, by influencing the amount and direction of cellular growth It is unclear what specific genetic modules contribute to the gradient of lateral blade growth hypothesized in such models [3, 7]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
