Forces in plant development

Ecole d'été organisée par :Eva Pebay-Peyroula, IBS, Grenoble, FRChristine Ziegler, Univ. Regensburg et MPI Frankfurt, AllemagneYves Gaudin, VMS, Gif-sur-Yvette, FRHugues Nury, EPFL Lausanne, Suisse et IBS, Grenoble, FRFrançois Parcy, iRTSV/PCV, Grenoble, FRRob Ruigrok, UVHCI, Grenoble, FRThe development of living organisms relies on complex molecular regulations. Because organisms also are physical objects, the mechanics of growth need to be incorporated to fully understand how changes in shape are controlled. This chapter explores this molecular and mechanical nexus, mainly using examples from the plant world obtained from the recent literature. The chapter is divided in three main sections. First, some basic biomechanical concepts are explained, with a focus on the relationship between force and shape. In the second section we investigate how the mechanical properties of cells help to build a tissue and, in turn, how tissue shape can prescribe a stress pattern that controls cell behavior. The third section explores mechanotransduction at the subcellular scale, with its implications for cell polarity. The overall picture is one in which the robustness of development relies on coordinated feedback loops that are both molecular and mechanical in essence