ROSI: a highly flexible root system imaging facility to study the root system development in gel

International audience

English. The root system architecture of plants plays a crucial role in foraging for soil resources. Soil is spatially heterogeneous in terms of chemical and physical properties and the root system architecture shows a great plasticity leading to a higher development in nutrient- or water-rich locations for instance (Lynch, 1995; Morris et al., 2017). Understanding the dynamics of root system development under environmental constraints is a requirement to improve plant resistance to stress, even in trees species, and requires phenotyping systems that provide images of high quality for accurate root trait analysis.Our root system imaging facility (ROSI) is a temperature controlled plant growth chamber that is provided with an automate and cameras which automatically perform white or infra-red imaging cycles. Flexible, it can accept gel plates of different dimensions or even small rhizoboxes. Taking advantage of ROSI, we study the root developmental response of in vitro gel grown poplar plants to mechanical constraints with either gel of high stiffness in split-root systems or with obstacles hindering root growth. The time-lapse imaging ability of ROSI allows monitoring the root daily, and even hourly, response to stress. The coupling of time-lapse imaging with root system analysis with SmartRoot (Lobet et al., 2011) provides an accurate description of the variation in RSA traits in response to any kind of stress. Our automate represents an important system for the process of accurately testing the effect of impaired environments on root system architecture of poplar grown in vitro.