The Primary Study Of Salt-alkaline Tolerance Mechansim Of Polygumn Sibiricum

The problem of salting and alkalinizing of fertile land, which decrease the produces of agriculture and influence environment, become more and more serious. In world, about 20% aera of plantation and half yield of irrigated field are affected by high salt content in soil, and there are more than 100 million acres of secondary salting plantation in China. It should be carried out by the modern forestry and agriculture that improving and utilizing the salting and alkalining land resource effectively and promoting the economic, social and ecological beneficial results of the produces of it. The way, employing biotechnology to enhancing the ability of salt-alkaline tolerance of forest trees and culture plants, is alternative. Cloning the related genes and studying the relationship with salt-alkaline tolerance and the mechanism of it, are foundations of promoting the salt-alkaline tolerance of plants by genetic project. Polygumn sibiricum is one of species that can survive with alkaline-patch in alkaline area (pH=9.5), and be abounded in genes, which take part in improving salt tolerance. In this essay, the changes of physiological indexes, protein expression map and EST data of Polygumn sibiricum after treat with NaHCO3 solution had been studied and analyzed, and discussed the mechanism of salt-alkaline tolerance of this plant, which provides the foundation for carrying out the project of cloning genes relating to salt-alkaline tolerance from Polygumn sibiricum. The results have obtained as follows:1 The diversity of response to salt-alkaline stress in different parts of Polygumn sibiricum is presented after treat with 3% NaHCO3 solution.2 After treat with NaHCO3 solution, the 'potassium reservoir' shift to the 'sodium reservoir' instem tissue.3 The change patterns of potassium, sodium and calcium contents in different parts of Polygumn sibiricum and the analysis results of EST data which had been sequenced from leaf tissue randomly indicate that there may be a cell Na+ extrusion pathway conducted by Ca2+ signal, similar to the SOS system in Arabidopsis thaliana, in leaf cell.4 SOD and POD act important roles in enhancing the salt-alkaline tolerance of Polygumn sibiricum after watering with 3% NaHCO3 solution.5 The change trends of proline content and EST data result of leaf tissue after treat with NaHCO3 solution shows that the proline dose not enhance the tolerance of salt-alkaline stress but expressed in background pattern. However, betaine acts as osmolyte and osmoprotectant in cell after watering with 3% NaHCO3 solution.6 A EST sequence in cDNA library, having high identity compared with sorbitol dehydrogenasesequence, indicates that sorbitol may act as osmolyte in Polygumn sibiricum after salt-alkaline stressed.7 After treat with 3% NaHCO3 solution, the total chlorophyll content is ascending, the ratio of chlorophyll a/b is declined and the photosynthesis rate is improved in leaf tissue, which demonstrate that Polygumn sibiricum is fit for living in salt-alkaline environment and the stress condition is propitious to its growth.