Study On Potato Transformation With Choline Monooxygenase Gene From Spinach

Drought and salinity is a serious problem all over the world, and is also an important factor limiting agriculture production in our country. Salinity soil not only decreases the productivity of cultivated land, but also seriously restricts its sustainable use, which directly affects the sustainable development of agriculture. Many important crops, such as rice, potato and tobacco, are sensitive to drought and salinity. Drought and salinity frequently cause the severe production losses of crops due to lack of effective tolerance mechanism. With the development of genetic engineering, many functional genes with a great ability to enhance the plants of salt tolerance have been cloned.As one of the most important osmotic substance in higher plants, glycine betaine plays a significant physiological function in regulating the adaptability to environmental stress and in enhancing the osmotic stress resistance in many plants. Choline monooxygenase (CMO) is one of key enzymes for synthesis of glycine betaine. Potato is unable to synthesize glycine betaine. Introduction of CMO gene and establishing a glycine betaine biosynthetic pathway in glycine betaine-deficient crops through genetic engineering, which could be enhanced drought and salinity tolerance of crop plants.The main purpose of the study was that CMO gene driven by the constitutive expression promoter CaMV 35S and the stress induced expression promoter rd29A were introduced into two potato cultivar Shepody and Favorita by Agrobacterium tumefaciens mediation, and further to study the effect of transgenic CMO gene on potato drought and salinity tolerance, which could enrich transgenic theory of plant and provide theoretic basis to breed new stress-resistant crop varieties. The manin results as following:1. Microtubers of two potato cultivars Shepody and Favorita were induced with two culture methods of solid medium and liquid medium culture, and Agrobacterium-mediated genetic transformation system were also investigated for them. The result from effect of light intensity on transformation of potato microtuber demonstrated that the light intensity of 2000 lux was beneficial to resistant shoot formation directly from transformed microtuber discs and the transformation efficiency of potato microtuber could reach to 51%.2. Microtubers of two potato cultivars Shepody and Favorita were used as the dornors and the expression vectors containing the CMO gene under the control of the constitutive expression promoter CaMV 35S and the stress induced expression promoter rd29A were used as the expression vectors, respectively. Some putative transgenic potato plants were obtained by Agrobacterium-mediated transformation. PCR analysis preliminary showed that CMO gene has been integrated into the genome of potato.3. Morphological observation of the transgenic plants showed that the characteristics of them were normal, and no abnormal transgenic plants were observed in the experiments. The growth of the transgenic plants and non-transgenic plants was similar under drought and salt stresses. The results indicated that the effect of transgenic CMO gene alone was not remarkable to improve drought and salinity tolerance of the transgenic potato plants.