Tissu d'un épiderme de maïs observé en microscopie optique

Maize epidermal tissue, viewed through an optical microscope. Cell walls and nucleus membranes are stained with toluidine blue dye. Four different cell types can be seen. The large oblong cells are mesophyll cells. The egg-shaped structures are stomata, accompanied by two guard cells. This fragment of epidermis is divided into two parts by a rib: the large, elongated cells of the perivascular sheath surround the (invisible) vascular tissue. The blue colouring of the walls, and the serrated shape of the mesophyll cells are characteristic of an adult leaf. A major development milestone occurs when the plant stops producing juvenile leaves and produces adult leaves. It is then able to produce reproductive organs. This transition may occur at various ages, depending on the genotype, and will affect the plant's flowering date. Scientists at the Quantitative Genetics and Evolution unit in Le Moulon are studying the genetic, epigenetic and molecular control of qualitative and quantitative characteristics and their importance in the adaptation and evolutionary history of plant species. They optimise selection processes based on target characteristics (such as growth, development and adaptation), taking advantage of breakthroughs in genomics and genetic resources, and allowing for changes in environmental conditions and farming methods.