Comparison of salt-responsive gene regulation in rice and in the salt-tolerant Festuca rubra ssp. litoralis

To identify novel elements of plant salt stress adaptation, salt-induced transcript accumulation was compared in the model crop plant rice and in the halotolerant grass Festuca rubra ssp. litoralis by cDNA-array hybridizations. Results of the study show major differences in transcript expression profiles between the salt sensitive rice and the naturally halotolerant grass species. The data indicate that the salt tolerance strategy of F. rubra ssp. litoralis involves activated expression of genes with functions in osmotic and ion homeostasis, in metabolism, and general stress defense that is missing in rice. In addition, transcripts with a function in regulation of transcription, translation, signal transduction and protein turnover showed different transcriptional responses. Among other signaling elements that were regulated by salt in the halotolerant F. rubra ssp. litoralis but not in rice, the putative serine/threonine protein kinase SnRK1b (sucrose non-fermenting-1-related kinase 1) was identified. It is hypothesized that modification of signal transduction pathways and transcriptional control in salt-sensitive species according to regulatory mechanisms identified in related halophytes can activate the complex network of molecular processes that lead to an improved tolerance of salinity.