Tansformation Of Salt Tolerant Gene In Upland Rice (Oryza Sativa L.) And Slat-tolerance Ability Evaluation

Through gene engineering approach, Betaine-aldehyde dehydrogenase (BADH) gene has been transformed into upland rice that has carried mannitol-1-phosphate (mtlD) gene and inherited it steadily, which not only help to breed transgenic upland rice varieties with salt tolerance, but also be beneficial to exploit and utilize alkaline land and to enlarge the planting area of upland rice.The BADH gene was transferred into the upland rice by Agrobacterium-mediated transformation, and in this transformation, the calli induced from mature and immature embryos was taken for experimental material. The integration and expression of exogenous gene in upland rice genome were studied, and at the same time, after the factors influencing transformation had been discussed carefully, a highly efficient transformation system was established.The results of PCR and Southern blotting analysis showed that BADH gene had been integrated into upland rice genome successfully. PCR again, the results showed that the mtlD gene and BADH gene were both integrated into upland rice. 44 transgenic plants with the mtlD gene and BADH gene has been obtained , including 28 upland rice 502 , 9 upland rice 277 , 7 upland rice 297. The expression of the BADH gene in the upland rice was proved by reverse transcription PCR.The plants T₀ with two extraneous genes appear lower plant height, shorter spike length and lower percentage of earbearing tiller. The transformed plant has a relative long growing season, 64.2% of the plants can fertilize, but the fertile ability declined, and the ratio of seed set between plants varies a lot.The generation T₅ of upland rice carried mtlD gene steadily and the generation T₂ of upland rice carried BADH gene steadily were cultivated in 0.5%-0.6% NaCl alkaline land in Dongying, Shandong province. Most of the transgenic upland rice could grow normally, while the nontransgene plants can not grow (upland rice 502). Based on the main agronomic traits investigation, PCR checking, and slat-tolerance ability evaluation, 9 lines, including T008, T006, T526, T566, T410, T461, T036, T122, T136, were selected. The rice quality of these plants reached national rice criterion level I ^level II, and lines yield vary from 7.895g¹2.89g.The salt-tolerance ability test of transgenic plant indicates that, the plant, which has been transformed two genes, exhibited high salt-tolerance ability, reached 0.75% NaCl(w/v). While the nontransgene plants can not grow in water culture included 0.75% NaCl(w/v).When the transgenic off-springs with one exogenous gene and the plants with two exogenous genes were subjected to 0.75%(w/v) NaCl, the appearance, relative electric conductivity, and the Na+/ K+ content of the plants indicate that the latter exhibits higher salt-tolerance ability. So we concluded that the two genes (mtlD and BADH) have certain interaction, and use polygenes transformation to improve plant's salt-tolerance ability is reasonable.