الفهرس | Only 14 pages are availabe for public view |
Abstract Five Egyptian lentil cultivars, Giza 4, Giza 9, Giza 51, Giza 370 and Sinai 1 were examined at different levels of NaCl (control (dist. water) , 2000, 4000, 8000, 16000 and 32000 ppm) in order to determine the most tolerant and the most sensitive lentil cultivars. The inhibitory effects of NaCl differed, depending on the genotypes tested. Increasing of NaCl concentration showed a decrease in the germination percentage (%), root-shoot length, relative water content and K+/Na+ ratio. The most reduction in root and shoot length was detected in Giza 4 followed by Giza 370, Giza 51, Sinai 1 and Giza 9. The highest water content was detected in cultivar Giza 9 followed by Sinai 1, while the lowest contents were detected in Giza 4, Giza 51 and Giza 370, respectively. Giza 51 showed the highest K+/Na+ ratio followed by Giza 9, Giza 370 then Giza 4 and Sinai 1. from the previous results, Giza 9 was the most salt-tolerant lentil cultivar among the five chosen lentil cultivars, while Giza 4 was the salt sensitive cultivar. Mitotic index, activities of some antioxidant enzymes, calcium binding proteins and SDS-PAGE protein profiles, as well as six ISSR markers were used to characterize the two selected lentil cultivars (Giza 4 and Giza 9). Giza 9 cultivar showed the highest mitotic index value and higher proline content compared to Giza 4. The SDS-PAGE protein profiles of Giza 4 and Giza 9 were variable, where Giza 4 showed higher polymorphism than Giza 9. Six ISSR primers were used and unique bands in each primer profile could be used as molecular markers for both Giza 4 and Giza 9. The relative gene expressions of ADH, CYS3, APX, SOD, and GR were significantly upregulated in Giza 9 roots after 24h of high salt treatment (250 mM), while CAT transcripts level was nonsignificantly reduced (by 0.5- fold) in relation to control. However, in Giza 4, only CAT gene was significantly upregulated in both root (2.3-fold) and shoot (8.5-fold) tissues. Investigation of ascorbate-glutathione enzymatic activities revealed that compared to shoot tissues a significantly higher ascorbate peroxidase (APX) and glutathione reductase (GR) activity was observed in root tissues of cultivar Giza 9. Moreover, endogenous reduced glutathione (GSH) content as well as reduced ascorbate content (ASC) was significantly high in the roots of Giza 9 compared to Giza 4. These results strongly indicate the involvement of ascorbate-glutathione cycle in the tolerance mechanism of Giza 9. Furthermore, exogenous application of 350 M of GSH assisted Giza 4 seedlings to tolerate salinity stress. |