XVI International Botanical Congess

Patterns of cell division and tissue expansion have been followed in individual sunflower leaves from initiation to the end of expansion, in a large range of environmental conditions including temperature, radiation and soil water status. Final area of individual leaves at a given position on the stem can have 10-fold variation without changes in epidermal cell area. Spatial and temporal analyses of cell division and tissue expansion revealed that both processes followed similar patterns during leaf development and that they had common responses to temperature, radiation and water deficit. These results suggest that cell division and tissue expansion are coordinated during leaf development either because they depend one of the other or because enzymes involved in each processes have common responses to environmental changes.