The Use of Embryo Cultures for Studying Salt Stress Tolerance of Four Different Bread Wheat Varieties and Their Promising Mutants

Abstract

The present study was carried out to determine the genetic response of four different bread wheat varieties and their mutants for callus induction using mature embryo culture and salt stress tolerance and to assess the genetic diversity between them using ISSR markers. The results of the ability of callus induction revealed that differences among genotypes, callus induction media (CI) and their interactions were highly significant for callus induction frequencies (CIF). Also in relation to the callus fresh weight (CFW), the differences between genotypes and their interactions with media were highly significant, whereas insignificant differences were found between media after 14 at 28 days of culture. The best medium for CIF was CIM2 containing 2 mg/l of 2,4-D for all genotypes except Gemiza 9-1 and Sakha 93-3 had the best CIF of CIM3 containing 3 mg/l of 2,4-D. Seds 12-7 had the highest CIF, whereas Sakha 93-3 had the lowest CIF of CIM2. Gemiza 9-1 had the highest CFW, whereas Sakha 93-3 had the lowest CFW after 28 days of culture. The fresh callus produced after month was transferred to salt stress media at 10000ppm NaCl level. Giza 168, Gemiza 9 and Sakha 93 showed increase in CFW, whereas other genotypes strongly decreased. Sakha 93 and Gemiza 9 gave the lowest value of callus necrosis (CN) and the highest value of callus in vitro tolerance (CINTOL) at the 10000ppm NaCl level after 28 days on salt stress media. The salt stressed callus was tested for shoot induction ability; callus of Gemiza 9 and Sakha 93 showed the best shoot induction frequencies at 10000 ppm level. Days to shoot induction were decreased with the increase of salt levels compared to normal conditions. Transfer of shooty callus on plant regeneration media to be grown and development failed. The callus turned brown and some of the resulting growths were weak and white. The use of ISSR technique illustrated the genetic similarities between the wheat genotypes, which ranged from 0.638 to 0.979 with an average of 0.809, suggesting a high genetic diversity between the wheat genotypes. Cluster analysis performed to generate dendrogram showed that wheat genotypes had been clustered into two main clusters. From the previous results, we recommended that Gemiza9 and Sakha93 are good materials for salt stress tolerance of bread wheat breeding programs..