Function Analysis Of Arabidopsis AtGLN1;1and AtGLN1;5Gene Under The Conditions Of Different Nitrogen Source And Adversity

Salt stress is one of the most serious environment factors that affects seed germination and seedling growth of plants. Salt stress is one of the most serious environment factors that affects seed germination and seedling growth of plants, the responses to salt stress during germination and seedling stage reflects the mechanism that plants adapting negative environment. During germination, plenty of protein degraded and the seeds are especially sensitive to salt stress, salt-inhibition of germination intensively occurs after vernalization, the mechanism of ammonium toxicity and inhibition from salt was not clear enough on seed germination now.The glutamine synthetases (GS) participate in nitrogen metabolic process, are exiting in any organisms, their main function is to assimilate NH4+to glutamic acids then formed into glutamines. Because of this function, glutamine synthetases are speculated could remit the ammonia toxicity generated from salt stress. In this research AtGLN1;1and AtGLN1;5genes of Arabidopsis thaliana were used to investigate their expression profile and the response to different environmental nitrogen sources and stresses, attempts to reveal the relationship between salt stress and nitrogen metabolism on the seed germination period.In this research, expression profiles of AtGLN1;1and AtGLNl;5in the wild-type Arabidopsis were examined, and their expression features in response to different environmental stresses and nitrogen resources were also determined. The results showed that during seed germination, the expression of AtGLN1;1was declined as the germination proceeding; the expression of AtGLN1;5could be detected in the beginning stage of germination and was almost disappeared in the seedlings. In the leaves of seedlings, the expression of AtGLN1;1was induced by salt stress, and was firstly induced then inhibited under mannitol stress and by KNO3or NH4Cl nitrogen source. The expression of AtGLN1;5was firstly induced then inhibited under salt stress and by using KNO3or NH4Cl as nitrogen source, and was inhibited under mannitol stress. In the roots of seedlings, the expression of AtGLN1;1was induced by salt stress and by KNO3nitrogen source, firstly induced then inhibited under mannitol stress and by NH4Cl nitrogen source. The expression of AtGLN1;5was inhibited under salt stress and mannitol stress, but could be induced by KNO3and NH4CI nitrogen source.Further results of overexpression transgenic plants or mutants of the Arabidopsis AtGLN1;1and AtGLNl;5under the salt stress, mannitol and different nitrogen sources treatment showed that the overexpression of AtGLN1;1and AtGLN1;5could contribute to the seed germination under salt stress and mannitol stress and strengthen the germination process when using KNO3or NH4Cl as nitrogen source, and could promote the growth of seedling in the poisoned NH4+conditions. The phenotype of glnl;1and glnl;5mutants did not suffer from mannitol stress, but the root length of glnl;1and glnl;5seedlings were shorter than that of the wild-type, and also the fresh weight were lighter.