Aquaporins and the responses of plants to their challenging environment

CHRISTOPHE MAUREL; VERONIQUE SANTONI; DOAN-TRUNG LUU; LIONEL VERDOUCQ; COLETTE TOURNAIRE-ROUX; MOIRA SUTKA; GUOWEI LI; YANN BOURSIAC; MICHAEL WUDICK; OLIVIER POSTAIRE

Cluj-Napoca

Congreso; The first world congress on water channel proteins (aquaporins and relatives) celebrating the 25th anniversary of the discovery of the first water channel protein (later called aquaporin 1); 2011

Introduction. Plants have to constantly adjust their water status during development and in response to sometimes many challenging environmental conditions. Uptake of soil water by roots and its delivery from xylem vessels to inner leaf tissues are crucial for maintaining the plant water status. The present talk will discuss how the integrated function and regulation of plant aquaporin can be addresses by a combination of genetic, molecular and physiological approaches and show how aquaporins contributes to water transport throughout the whole plant body. Results and discussion. Know-out mutants of Arabidopsis thaliana for plasma membrane aquaporins (PIPs) were used to dissect the osmotic/hydrostatic modes of water uptake in roots and leaves. The variation of root hydraulic arquitecture and of aquaporin expression in natural accession of Arabidopsis provided complementary insights into the role of specific cell layers and aquaporin isoform in root water transport. Aquaporin are also crucial for adjusting cell and tissues hydraulics in response to various experimental stimuli. Several studies have highlighted the role of reactive oxygen species (ROS)-dependent signaling paths, phosphorilation, gating and sub-cellular trafficking of aquaporins in the responses of roots and leaves to water stress, anoxia or changes in irradiance. In particular, the mechanism and routes of ROS-depending trafficking of PIPs were recently dissects in root cortical cells. Our studies also established stress-induces quantitative changes in aquaporin phosphorylation and, for the first time, a link with the plant aquaporin subcellular localization. Beside environmental stimuli, auxin was found to regulate aquaporin expression and roots hydraulic conductivity in connection with a novel role for a PIP isoform in lateral root emergence. Finally, the alteration of meshopyll conductance to CO2 in some PIPs knock-out mutants will be discussed with regard to the model that PIPs facilitate CO2 diffusion across plant cell membranes. Conclusion. A while range of selective profiles and regulation properties allows aquaporins to be integrated in numerous functions, throughout plant development and during adaptation to variable living conditions. In particular, the possible coupling of tissue hydraulics with growth and carbon assimilation provides unique research perspectives in plant integrative biology.