Intergrative Systems Analysis of the shoot apical Meristem – ISAM

The aim of the project iSAM is to understand how complex structures and patterns are produced at the growing tip of the plant shoot using combined modelling and experimentation. The shoot tip contains the shoot apical meristem (SAM), a population of dividing, undifferentiated cells that generates leaves and other organs in highly ordered patterns at shoot tips throughout the life of the plant. The SAM therefore has two functions. First it houses at its centre a stem cell population that is stable throughout the life cycle of the plant, which may be hundreds of years in the case of long-lived trees. It also initiates organs, and, since plant growth arises from the repeated production of new organs as the plant grows, the SAM is responsible for specifying all aboveground plant tissues. It therefore determines plant architecture and, indirectly, many aspects of agricultural productivity. The SAM has been extensively studied and we know many of its molecular and cellular components, but we do not understand how these components assemble into the multicellular structure with specific shape and growth dynamics. It is these questions this project will address using an iterative process of analysis, model building, biological testing and refinement.The individual cells within the SAM interact by exchanging signals and the interaction network that feeds back on the 'machineries' of individual cells, controlling local growth through the modulation of division rates. Added up, the local cell proliferation rates, patterned by the signalling networks, lead to specific shape changes. To understand the SAM, we will use a complex systems modelling approach, focusing on the interaction networks provided by the key plant hormones auxin and cytokinin.This proposal links four leading research teams in UK, France and Finland, bringing synergistic expertise and technologies in imaging, modelling, plant hormones and cell cycle to address this important systems problem