Physiological Response Under Drought Stress And The Cloning And Analysis Of Drought-Tolerance Related Genes In Nostoc Flagelliforme

Nostoc flagelliforme is a kind of terrestrial cyanobacteria with strong drought resistancs, it has high economic and medicinal value, and plays an important role in protecting ecology environment. At present, the research of drought stress resistance mechanism in Nostoc flagelliforme attracts more and more attention. In order to explore the self-protection mechanism of Nostoc flagelliforme under drought stress, we used the method of simulated drought stress to treat the liquid suspension cultured Nostoc flagelliforme cells and studied the changes of physiological characteristics in Nostoc flagelliforme under drought stress, then clone the drought stress responsive related genes. The mian results were summerizrd as follows:First of all, the experimental results revealed the impacts of drought stress on the growth of cell, antioxidant activety, and osmosic regulation substance. After treated with PEG-6000 under different concertration, the growth of Nostoc flagelliforme cell were inhibited in the early, gradually recovered later.The contenes of Chlorophyll-a were increased on the whole. The SOD, POD, CAT and NR activity increased, and declined later. The contents of proline (Pro) and extracellular polysaccharide (EPS), MDA, always increased under the low drought treatment, but thecontents of proline and soluble peotein showed a trend of decline under the high concertration PEG-6000. The results indicated that Nostoc flagelliforme can mobilize its own antioxidant enzymes to enhance their antioxidant capacity to eliminate or reduce the toxic reactive oxygen species, on the other hand, Nostoc flagelliforme can accumulate the contents of osmotic subtance to maintain the balanc of osmotic intracellular and ensure the normal metabolism of cell, then alleviate the damage of drought stress.Peroxiredoxin gene、glutathione reductase gene and oxidoreductase gene were cloned from Nostoc flagelliforme, and the gene sequences were analyzed and predicted by the tools of bioimformatics. The results showed that the peroxiredoxin was a hydrophilicity protein without signal peptide and colis, and highly conservative protein sublocated in cytoplasm. The glutathione reductase was a hydrophilicity protein without signal peptide and colis, having transmebrance structure and stability. The oxidoreductase was an instability protein that sublocated in cytoplasm, without transmebrance structure and signal peptide, having coils. The results provide reference imformation for further study the mechanism of drought related genes in Nostoc flagelliforme.At last, the prx gene、gr gene and ox gene were analyzed by real-time PCR technique. The result revealed that expressions of three genes were all up-regulated expressed under drought stress, which showed that these genes maybe involved in drought stress response in Nostoc flagelliforme.