Phiv, Histocytologie and plant cell imaging platform

Research

The general goal of PHIV is the development via innovation of in situ and in vivo imaging techniques of the main organic molecules.

Our research projects expand in two main directions :

Axe 1 : characterization via imaging techniques of molecular mechanisms involved in response and adaptation to changing abiotic environmental conditions. Our research aimed to identify and follow the expression of genes involved : (i) in the transport of ions: sodium, potassium (AtHKT, HcSKC, HcTRK), nitrate (the role of efflux transporters in the nitrate stomatal functioning), Fe (AtYSL, AtFer (iron storage)), heavy metals such as Zn and Ni (TcYSL), water transport (aquaporins) in contrasting abiotic conditions, in Arabidopsis thaliana and rice and (ii) in determining the root plasticity in response to growing conditions (eg phosphate deficiency, salt stress ...).

These themes are developed in close collaboration with teams of the UMR : Plant Molecular Biochemistry and Physiology (INRA Montpellier) and rely heavily on the use of two technologies, the localization of messenger RNA by in situ hybridization and localization of protein by immunocytochemistry. The PHIV team has developed and adapted these techniques to the study of molecules weakly expressed in cells, as is usually the case with ion transporters, transcription factors or plant hormones (indole 3-acetic acid). Finally, these approaches also rely on a dynamic imaging, by following gene expression in tissues of transgenic lines containing fusion proteins between the genes of interest and GFP, using confocal and multiphoton microscopy.

PHIV in January 2009 introduced in the Agropolis Foundation, a project entitled “Green Imaging: Coupling proton and photon imaging: towards a functional 3D imaging in plant”. The overall objective is to develop functional imaging of organs and plants under stress by combining the approaches NMR and multiphoton microscopy (collaboration with the Platform “NMR imaging” at INRA Clermont-Ferrand-Theix)

Axe 2 : Structural and dynamic characterization of primary meristems that control plant growth and development. To do this, we first develop techniques for 3D imaging of root and shoot meristems to generate from 2D images, a 3D reconstruction bearing structural and functional information. These techniques rely heavily on multiphoton microscopy still under-used in plants. In a second step we seek to develop from the microscopy-obtained 3D reconstructions, algorithms on how to process image (segmentation) in order to extract the biological interesting information. From the data acquired on rice, we try to develop a meristem-type 3D geometric model that can be adapted to different plants and different problems. This generic model will reach the complete geometrical characterization of the structures and the understanding of the meristem functioning combining geometry, physical constraints, physiology and growth (cell division and growth). This study is conducted in conjunction with Yan Traas and with the team INRIA-CIRAD "Virtual Plant" for the development of algorithms and model building (presence of a PhD in cotutelle PHIV and Virtual Plant). This project is financed (ATP meristem).

Our actions are designed to develop the interface 3Dimaging - modeling to support the integration of knowledge gained from the functional genomics towards the modeling of the plant development, an critical issue for the control of plant development in the future.

© Cirad • imagerie@cirad.fr