1. The Investigation Of The Physiological Factors Which Deciding The Content Of Potassium In The Flue-Cured Tobacco Leaf 2. Construction Of Fusion Protein Plasmid Of The Fragment Of The Nitrate High-affinity Transporter Gene(TaNR2;1) From Wheat

The tobacco farmers used to remove an apex because the tobacco products can been greatly increased. However,the potassium level in the middle of leaves was decreased at the same time so that the quality of tobacco was declining. To cope with this problem we carried out the following experiments in the molecular physiological field in order to find the reasons of decreasing potassium content in the middle leaves of tobaccos without the apex and to discovery the effective method for improving the quality of flue-cared tobacco leaves. Tobacco seedlings were water-cultivated under the condition of K-deficiency or K-sufficiency . When the seedlings grew up and came into blossom,they were divided into several groups and treated differently,such as removing the apex,retaining the apex and applying hormone. The roots and the different part leaves were harvested respectively and then the contents of potassium,hormone (IAA,ZR) levels and the activity of ATPase were measured. Furthermore,the expression of ATP binding transporter gene in transcription level was investigated by using tissue blot and northern blot in the roots.The five conclusions can be drawn here. Firstly,potassium content of tobacco's different parts was significantly controlled by potassium concentrations in the culture solution. Secondly,corresponding potassium requirement,the up-ground parts of tobacco played a leading role as the regulation of the potassium assimilation from roots. Thirdly,the potassium content and the potassium distribution in tobacco were also affected obviously on the hormone in the apex of tobacco. This effect was closely related to the ATPase activity. Fourthly,the expression of ATP binding transporter gene in transcription level in the roots was dependent on both the potassium concentration of the culture solution and the hormone in the apex of tobacco. Fifthly,removing the apex and applying Auxin and ZR,potassium content of different part leaves were increased markedly. This measure may be adopted to meliorate the quality of flue -cured tobacco practically.