The incredible architectural complexity of plants

3D image of a molecularly labeled pollen tube of lady's slipper. The green signal shows the web-like structure formed by pectin polysaccharides in conjunction with cell wall protein complexes. This protein-regulated physical arrangement provides a support system for sustained plant cell growth. Ursina Rathgeb ©DBMV-UNIL Ensuring growth and development, sometimes sustained, without risking fragility. This is the delicate balance facing plants. The team led by Julia Santiago Cuellar, Associate Professor at the University of Lausanne, has revealed how a judicious arrangement of sugar molecules, like bricks, strengthens the plant wall and enables it to expand without exploding. This discovery has been published in the November 9, 2023 issue of the journal "Science". Combining extensibility, robustness and protective functions. Plant cells are distinguished by their extraordinary ability to use solar energy to convert atmospheric carbon dioxide (CO₂) into sugars. The latter are an inexhaustible source not only of energy, but also of building materials. Like links in a chain, sugars can assemble to form long polymers, known as polysaccharides. Arranged in a complex network around the plasma membrane of plant cells, these polysaccharides help build the cell wall. The cell wall acts both as a protective barrier and as the support for a pressurized, extensible skeleton, giving the plant its rigidity while allowing plant cells to expand. When these cells change shape, grow or divide, they have to remodel their cell wall architecture. Growth without explosion. One question remains, however: how do plant cells organize their cell wall structure so that they can grow without the risk of exploding?