| The present study was conducted to identify the physiological and molecular mechanisms involved in the salt tolerance of Festuca rubra ssp rubra and Lolium perenne. The salt tolerance levels of 36 Festuca accessions and 52 Lolium perenne accessions were evaluated in the greenhouse under 5000, 7500, 10000, 12500 and 15000 ppm NaCl concentrations. The study identified PI 595057 and PI 632525 as salt tolerant and sensitive Festuca rubra accessions. PI 632542, PI 636644 and PI 618999 were found to be the most salt tolerant L. perenne accessions while PI 610932, PI 619002, PI 610924 and PI 632474 were the most sensitive accessions.;A study was conducted to investigate Na+, K+ and Ca2+ accumulation patterns in crowns, young leaves, old leaves, and roots of salt tolerant and sensitive F. rubra and L perenne accessions. Salt tolerant F. rubra and L. perenne accessions had lower levels of Na+ in crowns and leaves than sensitive accessions. The Na+ exclusion mechanism was found to be more efficient in L. perenne than in F. rubra. The results from this study suggested that Na+ exclusion and maintenance of a high K+/Na+ ratio in growing tissue are major salt tolerant mechanisms in both F. rubra and L. perenne.;A PCR based cDNA subtraction library was constructed from salt tolerant L. perenne cultivar PST 2J15, to identify the genes up-regulated under salt stress. From the 226 EST sequences selected, 85 (37%) EST sequences were found homologous to the genes involved in the salt stress response in plants. Two PCR-based cDNA subtraction libraries were constructed from salt tolerant (PI 595057) and sensitive (PI 632525) F. rubra accessions to identify genes up-regulated under salt stress; 199 and 47 EST sequences were selected from the tolerant and sensitive accessions respectively. The number of stress response genes identified in salt tolerant F. rubra (7%) were significantly less than tolerant L. perenne (37%). The results from this study helped in further understanding of the physiological and molecular mechanism of salt tolerance in F. rubra and L. perenne. |
