| According to statistics, the earth's environment becoming harsh is one of the main bottle necks for rapid development of global agriculture. Therefore, people are always seeking for an effective way to solve this problem,and mainly from the crops itself. Over these years, with the rapid development and gradual mature of molecular biology techniques, people put getting new varieties of transgenic plants as one of primary means of solving the problems. And so more and more stress proteins are studied. So far. People has found and cloned a number of related genes which can resist inverse bad environment and have great value in agriculture. Of course, Including LEA gene, one of the current hotpots in plant embryology and stress physiology.LEA gene, or Late Embriogensis Abundant Protein, it mainly expresses in matural seed and developmental stages of plants, and it is a class of low molecular weight protein. In follow-up experiments, LEA proteins were also found in pollen grains or roots or leaves in the situation of drought, high salt or low temperature. LEA proteins can participate in osmotic adjustment to stabilize the cell membrane structure in cell, and can combine ion and prevent oxidation, and can be as a molecular chaperone and dehydration protection agents, even can bind with the nucleic acid to regulat expression of other genes.Currently, there are many studies of LEA genes in home and abroad.People have discovered and cloned the LEA genes from cotton, barley, soybeans and carrots and so on, about 60 kinds of plants.and studied LEA genes and their products in-depth. However, for their function research,people mainly focused on resistance to salinity and drought, and in resistance to heat and cold. they have little research. The domestic and foreign research contending Chimonanthus praecox LEA genes were rare. Our laboratory constructed the first Chimonanthus praecox (L.) Link flowers cDNA library at home and abroad. In order to explore and verify the other functions of LEA genes in environmental stress,such as high temperature and cold, and to seek for its possible functions in plant reproductive growth, I carried out these experimental works as follows:1.Obtain sequence:According to the known sequence, we cloned sequence of LEA gene and analysis the sequence.2. Carry out fluorescence quantitative PCR analysis for the high and low temperature treated seedlings'expression of LEA gene:The results showed that in situation of high temperature, LEA gene's expression increased significantly in a short time, then for a long time decreased gradually, indicating that LEA has significant heat-shocking effect; in the low temperature stress conditions, in a long time, LEA gene's expression was gradually increased, and at 12h, the expression is maximum, and later there is no downward trend, indicating that LEA gene's expression was highly induced by low temperature..3.The fluorescence quantitative PCR analysis of expression characteristics c in Chimonanthus's different organs and its flower's different flowering phase, different organs: Results showed LEA gene have different expression in different tissues, indicating LEA gene's expression is significantly tissue-specific. Its expression is also varied in different flowering phase. And in germination period. it get maximum, suggesting that it may be plays an important role in low tempereture tolerance mechanism in plant. In the detection of floral organ, LEA gene of the pistil have the highest expression, so we hypothesized that it maybe regulates the development of female reproductive organs of plants.4.Construction of plant expression vector and transient expression analysis:In this study, LEA gene's plant expression vector pCAM-LEA was successfully constructed, laying the foundation for the subsequent experiments. Transforming by Agrobacterium mediated tobacco, GUS staining,we found leaves cultured showed obvious blue spot, which shows exogenous LEA has been introducted successfully into the plant cell.
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