A major challenge in morphometrics is to analyse complex biological shapes formed by structures at different scales. Leaves exemplify this challenge as they combine differences in their overall shape with smaller shape variations at their margin, leading to lobes or teeth. Current methods based on contour or on landmark analysis are successful in quantifying either overall leaf shape or leaf margin dissection, but fail in combining the two. Here, we present a comprehensive strategy and its associated freely available platform for the quantitative, multiscale analysis of the morphology of leaves with different architectures. For this, biologically relevant landmarks are automatically extracted and hierarchised, and used to guide the reconstruction of accurate average contours that properly represent both global and local features. Using this method, we establish a quantitative framework of the developmental trajectory of Arabidopsis leaves of different ranks and retrace the origin of leaf heteroblasty. When applied to different mutant forms, our method can contribute to a better understanding of gene function, as we show here for the role of CUC2 during Arabidopsis leaf serration. Finally, we illustrate the wider applicability of our tool by analysing hand morphometrics.
The authors declare no competing or financial interests.
E.B., M.C., J.B., A.K., M.O., A.B. and P.L. conceived the MorphoLeaf application that was encoded by E.B. with the help of P.A. M.C., A.M.-C., B.G., B.A. and P.L. performed the experiments and E.B., M.C., J.B., A.K., A.B. and P.L. analysed the data. J.B., E.B. and P.L. wrote the paper with input from all other authors.
This work was supported by the Agence National de la Recherche grants MorphoLeaf [project reference ANR-10-BLAN-1614] and LeafNet [project reference ANR-12-PDOC-0003]. M.C. was partly supported by the Fundacion Alfonso Martin Escudero. The IJPB benefits from the support of the Labex Saclay Plant Sciences-SPS [ANR-10-LABX-0040-SPS].
Movies 1-12 are available at http://morpholeaf.versailles.inra.fr/video/videoArabidopsis.html.
Supplementary information available online at http://dev.biologists.org/lookup/doi/10.1242/dev.134619.supplemental
- Received December 30, 2015.
- Accepted June 13, 2016.