, Volume 56, Issue 4, pp 771-774
Date: 29 Mar 2012

Stomatal NH3 compensation point and its metabolic regulation in senescence phenotypes of Nicotiana tabacum

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We compared stomatal ammonia compensation point (χs) and its metabolic regulation in tobacco (Nicotiana tabacum) leaves of a quick-leaf-senescence phenotype ZY90 and a slow-leaf-senescence phenotype NC89. Compared with NC89, ZY90 had significantly higher χs values between 40 and 60 d after leaf sprouting in spite of its lower nitrogen content. During the same time, a steeper decline in glutamine synthetase activity was detected in ZY90 leaves, simultaneously with a steep increase in χs. These results suggested that the quick leaf senescence phenotype exhibited high NH3 emission potential due to efficient nitrogen recycling and remobilization, and glutamine synthetase played a key role in regulating χs in ZY90.