Human society is entirely dependent on photosynthetic organisms as the pri-mary producers of food, feed, fiber and fuel. Moreover, comprising over 99% of the earth’s biomass, photosynthetic organisms also have a major impact on the global climate. Therefore, understanding how plants grow and how this growth is affected by the environment is a subject of vital importance. Plants grow in ways that are very different from animal growth. At the cellular level, two key differences are the presence of the chloroplast, a specialized or-ganelle where photosynthesis takes place, and the cell wall.

The cell wall is a biochemically complex extracellular matrix that counteracts the hydraulic pressures of up to 50 atm exerted by the protoplast. While the wall must be extremely rigid to withstand these forces, at the same time it must allow cell division and expansion in volume by a factor of 1000 or more. At the tissue and organ level, growth is regulated and coordinated by signaling systems that have a similar logic as those of animal systems but rely on a different biochem-ical circuitry.

At the level of the organism, growth and development have the unique characteristic that they continue throughout the lifetime of the plant. Such continuous post-embryonic development enables the plant to adjust its growth and development in response to environmental stimuli, and helps se-cure survival under adverse conditions. Our studies will focus on the model plant Arabidopsis thaliana, for which a multitude of tools for genetic, molecular and cellular manipulation and analysis are available.

The general aims of the RTD project “Plant Growth in a Changing Environment” are to:

• 1. Study plant growth quantitatively at the cellular, tissue and whole plant levels
• 2. Enhance our mechanistic understanding of growth-environment interac-tions
• 3. Explore new approaches to sustainable agriculture in a changing climate
• 4. Promote synergy between plant molecular biology, mathematics, physics and engineering
• 5. Train a new generation of “systems biologists” who are involved in inter-disciplinary projects and can readily cross boundaries between fields be-cause they are exposed to plant molecular biology, mathematics, physics and engineering