Drought effect on nitrate reductase and sucrose-phosphate synthase activities in wheat (Triticum durum L.):: role of leaf internal CO2
Drought effect on nitrate reductase and sucrose-phosphate synthase activities in wheat (Triticum durum L.):: role of leaf internal CO2
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DOI：
10.1093/jxb/erm150
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发表时间：
2007-09-01
影响因子：
6.9
通讯作者：
Cornic, Gabriel
中科院分区：
文献类型：
--
作者：
Fresneau, Chantal;Ghashghaie, Jaleh;Cornic, Gabriel
为了研究叶片内部CO2摩尔比下降对硝酸还原酶（NR）和蔗糖-磷酸合成酶（SPS）活性的影响，以小麦（Triticum durum）叶片为试验材料，分别进行了缓慢或快速脱水、环境CO2浓度和脱落酸（ABA）供应下降的处理。与文献一致，当净CO2同化（A(n)）降低45%时，缓慢脱水叶片NR活性被抑制约50%。胁迫叶片在5% CO2空气中保持4 h或复水2 d后NR活性仅部分恢复。NR活性对环境CO2摩尔比有轻微的依赖性，在无CO2空气中放置4 h后，NR活性下降了30%。在ABA供应（通过蒸腾流）和非胁迫叶片快速脱水后，NR活性的下降与低CO2处理下的下降相当。总的来说，这些数据表明，干旱引起的叶片内部CO2浓度下降只是引发NR活性下降的部分信号。与大多数文献不同的是，在缓慢脱水过程中，当A(n)下降40%时，SPS活性增加了30%。在5% CO2空气中处理4 h和复水后处理2 d，胁迫叶片的SPS活性分别略有增加和不变。与NR活性相比，低CO2对水分充足叶片SPS活性的影响较小。在非胁迫叶片中，4 h内快速脱水和通过蒸腾流补充ABA可以模拟SPS活性的增加。在硬粒小麦中，SPS活性的增加可能与干旱胁迫下基于aba的信号传导有关。
In order to study the impact of a decline of leaf internal CO2 molar ratio on nitrate reductase (NR) and sucrose-phosphate synthase (SPS) activities, leaves of wheat (Triticum durum) were submitted to different treatments: slow or rapid dehydration and decline in ambient CO2 concentration and abscisic acid (ABA) supply. In agreement with the literature, NR activity of slowly dehydrated leaves was inhibited by about 50% when net CO2 assimilation (A(n)) decreased by 45%. NR activity of stressed leaves kept 4 h in air containing 5% CO2 or after 2 d of re-watering was only partially restored. NR activity was slightly dependent on ambient CO2 molar ratio, declining by 30% when non-stressed leaves were kept in CO2-free air for 4 h. The decline of NR activity after ABA supply (through the transpiration stream) and after rapid dehydration of non-stressed leaves was comparable with the decrease observed under low CO2 treatment. Overall, these data suggest that a drought-induced decrease of the leaf internal CO2 concentration is only part of the signal triggering the decline of NR activity. In disagreement with most of the literature, SPS activity increased during slow dehydration, being stimulated by 30% when A(n) declined by 40%. SPS activity of stressed leaves kept 4 h in air containing 5% CO2 or 2 d after re-watering was slightly increased or unchanged, respectively. By contrast to NR activity, SPS activity of well-hydrated leaves was hardly affected by low CO2. Increased SPS activity was mimicked, in non-stressed leaves, by a rapid dehydration within 4 h and by ABA fed through the transpiration stream. In durum wheat, the increase in SPS activity could be linked to ABA-based signalling during a drought stress.