| Potato (Solanum tuberosum L.) is an important staple food and vegetable crop worldwide. Soil salinity is a major constraint to the potato production capabilities and the area of fields. Salinity tolerance in potato has been a focus on conventional breeding techniques for a long time, but so far very few salt tolerance potato cultivars have been released. Both breeding and screening germplasm for salt tolerance improvement are economic and effective way to make use of the salinized land. Mutation breeding proves to be a common breeding method due to the simple operation, save space and less time-consuming. Mutation techniques in combination with in vitro culture proved a new and powerful technology for breeding and screening for salt tolerance crops and a promising and feasible approach to select and obtain salt tolerance variants. Ethyl methane sulphonate (EMS) has been widely used in plant breeding for the efficient mutation rate and low frequency occurred with the chromosome exchanges. It's deemed as the most widely used and the positive effect chemical mutagen apply to crop mutation breeding.The objective of this study was to adopt somaclonal variation in association with chemical mutagenesis and to measure the physiological and biochemical indexes of the salt tolerance variants under the condition of the salt critical concentration. The aim was to isolate and screen the salt-tolerance variants and to observe and evaluate the growth of salt-tolerance variants through in vitro micro-cuttings induced by EMS of cv.Gannongshu2 and cv.Qingshu2 that were transferred to plastic pot with the NaCl stress. The results were showed as following:1. The growth was inhibited in the presence of NaCl stress of the in vitro micro-cutting of cv.Gannongshu2 and cv.Qingshu2, decreased significantly in response to increasing concentration of NaCl. Under 1.0%NaCl stress, the leaf color presented yellow and the plantlet of potato in vitro stoped growing. So the salt critical concentration of the plantlet of cv.Gannongshu2 and cv.Qingshu2 in vitro was 1.0%NaCl.2. The growing ability was significantly reduced after the treatment induced by EMS in vitro micro-cutting of potato, and the most efficient EMS concentration and suitable treatment duration was 0.9~1.0%+4 hours for both the cv.Gannongshu2 and cv.Qingshu2 micro-cuttings. The lethal dose and treatment time was 1.2%+4h.3. The survival rate of micro-cuttings from cv.Gannongshu2 and cv.Qingshu2 treated by EMS in the presence of 1.0%NaCl stress was 20% and 15%, respectively. These variants presented stronger superoxide dismutase (SOD) activity, less cell membrane permeability, higher content of free proline and chlorophyll than the control. There was a performance of salt tolerance in these variants.4. Variants of salt tolerance were identified by transferring to plastic pot under the 1.0%NaCl stress. The result showed that they displayed stronger growth ability and higher salt tolerance when compared with the control. |
