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The Cloning And Expression Analysis Of Salt Stress Responsive Gene In Yeast

Posted on:2004-08-23Degree:DoctorType:Dissertation
Country:ChinaCandidate:C FuFull Text:PDF
GTID:1100360095455507Subject:Forest cultivation
Abstract/Summary:PDF Full Text Request
The progressive salinization of soil has made the genetic improvement of salt tolerance an urgent priority for the future of environment and agriculture. In the last few years significant advances have been made in the identification and isolation of several genes that could potentially be involved in the process of salt tolerance. Salt stress adversely affects the growth of plants and microorganism. To understand the molecular basis of salt-stress response and isolation the key salt tolerant gene , the salt induced ESTs and salt tolerant gene HAL1 in Yeast were cloned and their expression were analyzed.Suppressive substracted hybridization cDNA library was constructed employing specific NaCl-stressed cells and non-stressed cells from yeast stram(Zygosaccharomyces.rouxii 2.181). An efficient PCR-based cDNA substraction method was employed for the isolation of the salt-stressed responsive ESTs. Clones were isolated randomly and sequenced. The results of sequece analysis and homology comparation showed that some clones were homologous to genes that have earlier been implicated in stress response, other clones were novel with respect to their function and showed lower or no homology to sequences in the public database. Sequences of parts of the cloned ESTs in this research are new sequences in Zygosaccharomyces.rouxii.A salt tolerant gene HAL1 identified first in yeast by Gaxiol was also isolated in this research from a different strain of Saccharomyces cerevisiae. HAL1 is an important salt tolerant gene in yeast. HAL1 gene was transformed into tobacco plants and the screened transgenic plants showed improved salt tolerance than the control plants. The salt tolerance of tobacco plants transformed with HALl gene was compared with the transgenic tobacco plants with other salt tolerant gene. The results showed that although the salt tolerance of transgenic tobacco plants with HALl gene was higher than that of the control plants, it was lower than the salt tolerance of transgenic tobacco plants with exgenous gene encoding the enzyme controlling the synthesis of osmolytes. Osmo-stress and ion stress are the two important respects in salt stress, which couldn't be ignored. HALl gene can be induced by osmo-stress and plays an important role inthe efflux of Na+ , but it has no tolerance to the osmo-stress. Therefore the improvement of the salt tolerance in transgenic plants with HAL1 is limited. The co-transformation with HAL1 and salt tolerant gene controlling the synthesis of osmolytes can be expected to improve the salt tolerance of transgenic plants greatly.
Keywords/Search Tags:yeast, salt tolerant, responsive, gene cloning, suppressive substracion hybridization
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