In vitro Influence of Salinity Stress on Callus and Plantlets Regeneration of Apple Rootstocks

Document Type : Original Article


 IN this investigation a screening of two apple rootstocks (Balady ….and MM106) to salinity, stress was achieved for an attempt to introduce more tolerant apple rootstocks. Calluses of the two rootstocks were cultured on MS medium supplemented with NaCl as a source of salinity at five concentrations (0.00, 500, 1000, 2000, 3000 mg/l). Morphological characteristics of both apple rootstocks Balady and MM106, negatively responded to the raising of NaCl concentrations in vitro such as callus survival and regeneration percentages, plantlets length (cm), number of multiple shoots, number of leaves/plant, number of roots/plant and root length (cm). The higher salinity concentration (3000 mg/l NaCl) induced the lowest significant percentage of callus survival, especially with MM106 (32.0 %) if compared with control (60.0 %). The mean of regeneration percentage reached the maximum number with control (38.67 %), and decreased gradually with higher NaCl concentrations until it was (23.67%) with 3000 mg/l. It was feasible that salinity did not reduce the average length of shoots. Number of multiple shoots was affected by raising salinity level into medium. The highest significant value was obtained with control (0.00 NaCl) (14.00) while, the lowest significant Value was (8.50) with 3000 mg/l. Moreover, number of leaves per plant, were reduced under salinity stress, which (0.00 and 500 mg/l NaCl) treatments achieved the highest significant number of leaves Values (8.83 and 7.83), respectively, followed by 1000 mg/l (7.33). Balady was more tolerant than MM106 to salinity stress and the average number of roots was (6.27 and 4.80), respectively. The proline concentration in rootstock increased with the raising of salt concentration, meanwhile, total chlorophyll content decreased by the increasing of salt concentration in the culture medium. On the other hand, peroxidase, poly phenyl oxidase, alcohol dehydrogenase and malate dehydrogenase isozymes banding patterns represent differences in some bands density or absent bands with different NaCl concentrations if compared with control treatment.