A simple and versatile 2-dimensional platform to study plant germination and growth under controlled humidity

We describe a simple, inexpensive, but remarkably versatile and controlled growth environment for the observation of plant germination and seedling root growth on a flat, horizontal surface over periods of weeks. The setup provides to each plant a controlled humidity (between 56% and 91% RH), and contact with both nutrients and atmosphere. The flat and horizontal geometry of the surface supporting the roots eliminates the gravitropic bias on their development and facilitates the imaging of the entire root system. Experiments can be setup under sterile conditions and then transferred to a non-sterile environment. The system can be assembled in 1-2 minutes, costs approximately 8.78$per plant, is almost entirely reusable (0.43$ per experiment in disposables), and is easily scalable to a variety of plants. We demonstrate the performance of the system by germinating, growing, and imaging Wheat (Triticum aestivum), Corn (Zea mays), and Wisconsin Fast Plants (Brassica rapa). Germination rates were close to those expected for optimal conditions

The response to auxin of rapeseed (Brassica napus L.) roots displaying reduced gravitropism due to transformation by Agrobacterium rhizogenes

International audienc

Nematic Ordering Pattern Formation in the Process of Self-Organization of Microtubules in a Gravitational Field

Papaseit et al. (Proc. Natl. Acad. Sci. U.S.A. 97, 8364, 2000) showed the decisive role of gravity in the formation of patterns by assemblies of microtubules in vitro. By virtue of a functional scaling, the free energy for MT systems in a gravitational field was constructed. The influence of the gravitational field on MT’s self-organization process, that can lead to the isotropic to nematic phase transition, is the focus of this paper. A coupling of a concentration gradient with orientational order characteristic of nematic ordering pattern formation is the new feature emerging in the presence of gravity. The concentration range corresponding to a phase coexistence region increases with increasing g or MT concentration. Gravity facilitates the isotropic to nematic phase transition leading to a significantly broader transition region. The phase transition represents the interplay between the growth in the isotropic phase and the precipitation into the nematic phase. We also present and discuss the numerical results obtained for local MT concentration change with the height of the vessel, order parameter and phase transition properties

Modification of the gravitropic response of seedling roots of rapeseed (Brassica napus) transformed by Agrobacterium rhizogenes A4

International audienceModification of the gravitropic response of seedling roots of rapeseed {Brassica napus) transformed by Agrobacterium rhizogenes A4 V. Legue, F. Vilaine, M, Tepfer and G, Perbal Legue. V,. Vilaine, E. Tepler. M. and Perbal. G. 1994. Modification ofthe gravitropic response of seedling roots of rapeseed \Bra.ssica napii.\i transformed by Agrobacieiium rhi:ngem's A4,-Physiol, Plant, 91: 559-566. We have e.xamlued the growth and gra\ itropic response of seedling roots of rapeseed {Brassica napus. CrGC5-l) transformed by AgrobacWiiiini rhizogenes .\4. in order to evaluate if this could constitute a new model system for the study of gravitropism. The transformed clone chosen for study had integrated full-length TL-and TR-D.NA from pRi (the root inducing piasmid). and thus included all of the agrobacteriai genes potentially involved in the modified phenotype of transformed plants. In the vertical position, the gnnvth rate of transformed roots was higher than controls. During 24 h of continuous stimulation, the optimal angle for gravitropic bending in normal roots was 135° twith respect to the gravity a.sis). with decreasing response at 90° and 45^, Eor transformed roots, slight curvature developed at 45"' and at 90°. and stronger curvature was observed at 135. though transformed root tips never reached the vertical position. The minimum stimulation time necessary to elicit a response (presentation time) was also determined: it was significantly shorter in normal roots t80 si than in transformed ones * 120 s). The results show that pRi transformed roots are less sensitive to gravity than normal roots