A growth experiment on agar medium and a hydroponics experiment were carried out to study the nitrogen （N） metabolism of a low-N tolerant mutant （lntl） of Arabidopsis thaliana under different N levels as compared ...A growth experiment on agar medium and a hydroponics experiment were carried out to study the nitrogen （N） metabolism of a low-N tolerant mutant （lntl） of Arabidopsis thaliana under different N levels as compared with the wild- type （WT） Arabidopsis. On the agar medium, no apparent growth differences were observed between the lntl and WT plants under a normal N level of 9 mmol L^-1 NO3. However, under a low N level of 0.18 mmol L^-1 NO3^-, the growth of the WT plants was greatly retarded, while the lntl plants were not affected by low-N stress and showed similar growth with those grown under a normal N level. In the hydroponics experiment, the lntl mutant had higher activities of glutamine synthetase （GS） and NADH-dependent glutamate synthase （NADH-GOGAT） in both leaves and roots under N-deficient conditions. Moreover, they accumulated less ammonium （NH4^＋） but more free amino acids in leaves compared with the WT plants. These observations suggest that better N assimilation might contribute to the low-N tolerant phenotype of the lnt1 mutant.展开更多
基金Supported by the National Basic Research Program of China(No.2007CB109305)the National Natural Science Foundation of China(No.30370839)
文摘A growth experiment on agar medium and a hydroponics experiment were carried out to study the nitrogen （N） metabolism of a low-N tolerant mutant （lntl） of Arabidopsis thaliana under different N levels as compared with the wild- type （WT） Arabidopsis. On the agar medium, no apparent growth differences were observed between the lntl and WT plants under a normal N level of 9 mmol L^-1 NO3. However, under a low N level of 0.18 mmol L^-1 NO3^-, the growth of the WT plants was greatly retarded, while the lntl plants were not affected by low-N stress and showed similar growth with those grown under a normal N level. In the hydroponics experiment, the lntl mutant had higher activities of glutamine synthetase （GS） and NADH-dependent glutamate synthase （NADH-GOGAT） in both leaves and roots under N-deficient conditions. Moreover, they accumulated less ammonium （NH4^＋） but more free amino acids in leaves compared with the WT plants. These observations suggest that better N assimilation might contribute to the low-N tolerant phenotype of the lnt1 mutant.
