A genomics approach towards salt stress tolerance

Abiotic stresses reduce plant productivity. We focus on gene expression ana lysis following exposure of plants to high salinity, using salt-shock exper iments to mimic stresses that affect hydration and ion homeostasis. The app roach includes parallel molecular and genetic experimentation. Comparative analysis is employed to identify functional isoforms and genetic orthologs of stress-regulated genes common to cyanobacteria, fungi, algae and higher plants. We analyze global gene expression profiles monitored under salt str ess conditions through abundance profiles in several species: in the cyanob acterium Synechocystis PCC6803, in unicellular (Saccharomyces cerevisiae) a nd multicellular (Aspergillus nidulans) fungi, the eukaryotic alga Dunaliel la salina, the halophytic land plant Mesembryanthemum crystallinum, the gly cophytic Oryza sativa and the genetic model Arabidopsis thaliana. Expanding the gene count, stress brings about a significant increase of transcripts for which no function is known. Also, we generate insertional mutants that affect stress tolerance in several organisms. More than 400 000 T-DNA tagge d lines of A. thaliana have been generated, and lines with altered salt str ess responses have been obtained. Integration of these approaches defines s tress phenotypes, catalogs of transcripts and a global representation of ge ne expression induced by salt stress. Determining evolutionary relationship s among these genes, mutants and transcription profiles will provide catego ries and gene clusters, which reveal ubiquitous cellular aspects of salinit y tolerance and unique solutions in multicellular species. (C) 2001 Edition s scientifiques et medicales Elsevier SAS.