Overexpression Of Fructose-1,6-Bisphosphate Aldolase(SbFBA) Gene Enhanced Drought Tolerance In Arabidopsis Thaliana

Drought is one of the major abiotic stress factor affecting growth, development and normal metabolism of plants, seriously affected crop production. So studying and exploring the responses of plants to drought stress, especially the drought-tolerance mechanisms, enhancing crop drought-tolerance, realizing water use efficiency and crops till harvest have been largely studies. Recently, using transgenic technology to transfer some drought-tolerance related genes has been well developed, and has been the new way of breeding drought-tolerance varieties.The fructose-1,6-bisphosphate aldolase(FBA) is one of the important enzymes in the carbon metabolism and sugar metabolism pathway of the organisms,and this enzyme also play an important role in the Calvin cycle. It catalyzes reversible aldol condensation reaction of dihydroxy acetone phosphate and 3-phosphate glyceraldehyde yielding fructose-1,6-diphosphate.So it is involved not only in the glycolytic/gluconeogenic pathway, but also in the pentose phosphate cycle and the Calvin cycle, and has direct impact on the accumulation of sucrose and starch in plants, provides the energy for biological material synthetic metabolism of ATP and the substrate, So the fructose-1,6-bisphosphate aldolase(FBA) plays a crucial role in the cell life activities. However, there is few report on fructose-1,6-diphosphate aldolase in plant. Currently, the studies of FBA mainly focus on its influence on growth, biomass accumulation and participates stress response under adversity in the plant. But the specific mechanism of stress resistance is not clear. Based on this, three SbFBA overexpression Arabidopsis lines and wild-type Col, empty vector transformed line Col-Vec are used as the materials to study the difference of physiological and biochemical indexes which caused by FBA under drought stress, and to speculate the possible mechanism of FBA in improving drought-tolerance.The results of this study are as follows:1.The experiment of seed germination shows that the seeds of transgenic lines have a higher relative germination, germination potential and drought-tolerance index comparing with the seeds of control lines,which demonstrates that the seeds of SbFBA transgenic lines have strong ability to adapt to drought stress.2.From the point of growth, there are no significant differences between over-expression of SbFBA and wild-type Col, empty vector transformed Col-Vec under the condition of normal growth, but the growth of SbFBA overexpression lines showed obviously better shoot growth than Col and Col-Vec under drought stress. And the relative biomass of SbFBA overexpression lines is significantly higher than wild-type Col and empty vector transformed Col-Vec under drought stress.3.Under drought stress, the relative content of chlorophyll a, chlorophyll b and total chlorophyll of wild-type Col and Col-Vec showed decreasing trend, but the relative content of chlorophyll a of transgenic Arabidopsis showed a slight downward trend, the relative content of chlorophyll b and the relative content of total chlorophyll of transgenic Arabidopsis tend to be stable. It shows that drought stress has less effect on chlorophyll content in transgenic Arabidopsis. The transgenic Arabidopsis still maintain higher chlorophyll content under drought stress.4.There are no significant differences between the MDA content of SbFBA overexpression lines and the wild-type Col or Col-Vec under the condition of normal growth, with the increase of drought stress level, the MDA content of wild-type Col and Col-Vec showed rising trend earlier than SbFBA overexpression lines, indicating that drought stress caused membrane peroxidation of Arabidopsis, and the damage of oxidation of wild Arabidopsis is greater than the transgenic Arabidopsis.5.The osmotic potential of wild-type Col and Col-Vec is lower than that of SbFBA overexpression lines under the condition of normal growth, but it become the opposite under drought stress. And after mannitol stress processing of different concentrations, the soluble sugar content of SbFBA overexpression lines increased significantly, especially the content of sucrose.In conclusion, SbFBA overexpression lines can reduce the oxidative damage of the leaf, promote the soluble sugar accumulation, reduce the leaf osmotic potential effectively, increase the moisture absorption, improve the leaf water status, maintain the stability of cell membrane and promote chlorophyll synthesis to improve the drought resistance.