Improving Tobacco Stress Tolerance By OsNAS1 Gene Introduction

Drought, high salinity and low-temperature are common stress condition that adversely affect plant growth and crop production, which is a global problem。 How to promote the resist ability of crops to drought, high salinity and low-temperature and then increase crop production is a important question related to the national economy and the people's livelihood。 Compared with traditional breeding technique and molecular marker aided selection, it is a more attractive approach to improve the resist ability of crops by plant engineering.Nicotianamine-synthase (NAS) gene was got from Brazilian upland rice, it has been proved play an important roll in the adaptive reaction of ferrous stress, its catalysis product NA is the supporter in bivalent metal ions absorption and transportation in plants,it can be a inhibitory of Fenton-reaction as an antioxidation. OsNAS1 gene was one of expression pattern by salt treatment rice and it is a regulator of stress adaptation in plants, over-expressing OsNAS1 gene can enhance plant to tolerate drought and high salt or low temperature stress.In this paper, salt-induced gene OsNAS1 were studied in tobacco by a plant expression vector p2300-OsNAS1 containing the 35S promoter using Agrobacterium tumefaciens-mediated transformation. By PCR determination of transgenic plants, one transgenic lines were obtained.It was demonstrated that foreign genes expressed in transgenic tobacco.Transgenic tobacco plants over-expressing OsNAS1 gene conferred enhanced salt, drought and low-temperature tolerance under greenhouse condition.The indication of transgenic tobacco physiological index tell us that physiological index such as the net CO₂ uptake,soluble sugar content, SOD activity, CAT activity, is obviously higher than CK. at the beginning of stresses,. The variation tendency in the course of stress between transgenic plants and CK is similarly, but it changes more gently. The other relevant physiological index such as MDA content, injured- degree of membrane system are obviously lower than the CK at the beginning of stresses, and its variation tendency is also very slightly.We suggested that expression of NAS gene might result from improvement on antioxidative capacity and it improve the resist ability of transgenic tobacco.