Studies On Stress-resistant Physiological Function Of AtSP1 In Arabidopsis Thaliana

Abiotic stresses such as drought, high salt and extrame temperature influence plant growth, productivity and development. To cope with unpredictable environmental changes, plants evolve signal transduction mechanisms by which they receive stress signals and regulate their stress-tolerance reactions.It is known that the Stable Protein I (SP1) detected in Aspen plants remains soluble upon boiling and that sp1 expression in transgenic Aspen is resistance to salt stress. The study also reported that SP1 is a stress-related protein with no significant sequence homology to other stress-related proteins and may represent a new protein family. However, knowledge of the SP1 gene function, especially in stress responses, is still incomplete. Presently, we analyzed the effect of expression of SP1 by ordering At3g17210 gene mutant of Arabidopsis thaliana SALK₀23701,and through detecting the expresstion of the gene we have got homozygous,then at the same time we plant homozygous mutant and wild-type Arabidopsis thaliana under the salt, ABA, high temperature and low temperature stresses, etc.Training under the conditions,we found that the growth of the wild-type Arabidopsis thaliana under high temperature is better than the homozygous mutant's growth ,while under other conditions the growth of mutant and wild-type plants is similar.Because of this we speculate that the gene may be involved in the stress regulation of Arabidopsis thaliana growth under high temperature.The main results are as follows:1. The homozygous T-DNA mutants of the AtSP1 gene in Arabidopsis thaliana were identified at DNA and RNA levels, and its phenotypic changes were observed.2. The Semi-Quantitative RT-PCR was used for the analysis of the expression levels of AtSP1 gene in the different tissues and under abiotic stresses. The expression profiling showed that AtSP1 gene was highly expressed in roots and leaves, and less in stems, leafstalks and flowers.3. The high temperature induced a fast increase in mRNA level of the AtSP1 gene. The expression of the AtSP1 gene increases to the maximum with the high temperature for 3 h ,and slow down for 8 h.The different salt & ABA concentration as well as low temperature treatment had no effect on the expression of the AtSP1 gene in the experiments. These results indicatied that the AtSP1 gene was likely to be an important regulation factor in high temperature signal pathways.4. Under the high temperature treatment, the wild-type Arabidopsis thaliana plants grew much stronger than mutant's plants, and exhibited higher proline contents, total SOD activities ,PSII activities and lower MDA contents, which suggested that the wild-type Arabidopsis thaliana plants suffered less injure under high temperature.5. The most remarkable characteristics of the mutant was growth retardation,lengthened vegetative growth stage, decreased leaf volume, shortened hypocotyls as well as total length of the whole plants, and reduced resistance to hamful enviroment.