The shaping of plant axes and crowns through tropisms and elasticity: an example of morphogenetic plasticity beyond the Shoot Apical Meristem

International audience ; Shoot morphogenetic plasticity is crucial to the adaptation of plants to their fluctuating environments. Major insights on shoot morphogenesis have been gathered studying meristems, especially the Shoot Apical Meristem (SAM), through a methodological effort in multiscale systems biology and biophysics. However, morphogenesis at the SAM is robust to environmental changes. Plasticity emerges later on during post-SAM development. The purpose of this review is to show that multiscale systems biology and biophysics is insightful for the shaping of the whole plant as well. More specifically, we review the shaping of axes and crowns through tropisms and elasticity, combining the recent advances on the morphogenetic control by physical cues and by genes. We focus mostly on land angiosperms, but with growth habits ranging from small herbs to big trees. We show that generic (universal) morphogenetic processes have been identified, revealing feed-forward and feedback effects of the global shape on the local morphogenetic process. In parallel, major advances have been made in the analysis the major genes involved in the shaping of axes and crowns, revealing conserved genic networks among angiosperms. Then, we show that these two approaches are now starting to converge, revealing exciting perspectives.