| Rapeseed is one of the world's four major oil crops, with the feature of adaptable, versatile, high economic value and development potential. As the world's environment is deteriorating, increasingly scarce land resources, rapid development of industrial and agricultural production, population expands, growing demand for food, how to effectively resolve the problem that reclaim saline land has become the hot spots in many countries and regions. Previously, the breeders always used the conventional breeding methods to confer the rapeseed the ability of abiotic stress resistance, but it took long time to obtain the good strains. As the large advances of gene engineering and biotechnology has acquired, the method of introduce the target genes into the plant t to improved crop varieties, has been more and more widely used.Nicotianamine synthase gene (NAS) is the pivotal enzyme gene of plant growth and metabolism, it plays an important role in the iron absorption of the plants. The product—nicotianamine (NA), is not only as the phytosiderophore precursors, but also involved in the transport, distribution and storage of iron in plants. Currently, some reseachers found that it can be someother heavy metal ions transporter, which show strong resistance against the effects of heavy metals, the results open a new perspectives for the modulation of nicotianamine content in plants for phytoremediation. In order to breed a new variety which can have strong resistance to salt stress, we use the hypocotyls of Brassica napus. cultivar'Yangyou 6'as the explants for transformation and introduce the gene (Os NAS1) that can be induced by salt stress into the explants.The main result is as follows.The vector of pCambia2300-35S-OsNAS1-OCS has transfered into the Agrobacterium tumefaciens . The genetic transformation system of rapeseed hypocotyls was explored and optimized. Chose the seedlings growing on the MS medium for 4 days, cut the hypocotyls and preconditioned on the pre-culture medium (MS + 1.0 mg/L 2,4-D + 1.0 mg/L 6-BA, pH, 5.8) for 3 days. After 3 days, the preconditioned hypocotyls were inoculate with Agrobacterium tumefacience for 25min, then removed carefully to the cocultivation medium (MS + 0.1 mg/L 2,4-D + 1.0 mg/L 6-BA + 5.0 mg/L AgNO3, pH, 5.8) for 3 days. After cocultivation, the explants ?were transferred to the selection and differentiation medium (MS + 0.1 mg/L 2,4-D + 1.0 mg/L 6-BA + 5.0 mg/L AgNO3 +10 mg/L Kan + 500 mg/L Cef, pH, 5.8) to screen and induce the green calli. The larger calli which have selected under the Kan for 1～2 weeks, could be moved into the rooting medium (MS + 0.3 mg/ L NAA + 10 mg/L Kan + 500 mg/L Cef, pH, 5.8), then you could see the shoots and roots produced on the medium. After the shoots and roots formation, they would moved onto the 1/2 MS to make the seedlings growing better. The selected seedlings were conducted the molecular identification of PCR. Finally we obtained 50 positive transgenic plants, 18 of them transplanted into the soil, flowering and then harvested their seeds for the next step of the experiment. Compared the T0 generation with the not-transformant, we found that the seeds were congenital dysplasia, seeds shriveled and smaller than non-transformant, but when they germinated, they grew better than control. During the germinating of transgenic T0 seeds and control plants under salt stress, the results indicated that the transgenic seeds have more tolerance than control in the salt treatment.Additionally, we designed the experiment that irrigating the seedlings with 20 mM of sodium carbonate to study the tolerant degree of the T1 transgenic seedlings. After 9 days treatment, we observed the physiological changes between the transgenic and control, measured the enzyme activities of CAT, POD and root activities. The results suggest that the activities of root and CAT enzyme in transgenic T1 plants were higher than the control, while the POD activities showed no significant differences between the transgenic line and control except T1-110.
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