Nitrogen recycling and remobilization are differentially controlled by leaf senescence and development stage in Arabidopsis under low nitrogen nutrition
Nitrogen recycling and remobilization are differentially controlled by leaf senescence and development stage in Arabidopsis under low nitrogen nutrition
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DOI：
10.1104/pp.108.119040
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发表时间：
2008-07-01
期刊：
影响因子：
7.4
通讯作者：
Masclaux-Daubresse, Celine
中科院分区：
文献类型：
--
作者：
Diaz, Celine;Lemaitre, Thomas;Masclaux-Daubresse, Celine
以5个重组自交系（RIL）为研究对象，分析了它们在氮素限制条件下的叶片衰老表型差异（从早衰到晚衰），并以此为基础从Bay-0X Shahdara RIL群体中筛选出的5个RIL，以监测与N同化和N再动员途径相关的代谢标记。在每个RIL中，总氮、游离氨基酸和可溶性蛋白质含量随着叶片老化而降低。与此同时，N再动员标记物如胞质谷氨酰胺合成酶、谷氨酸脱氢酶和CND 41样蛋白酶的表达增加。这种增加发生在早衰老线比晚衰老线更早，更迅速。利用~（15）N示踪技术研究了水稻营养生长阶段~（15）N在源叶和库叶之间的分配，结果表明，在早衰品系中，N从源叶向库叶的再调动更为有效。营养生长期叶片衰老程度与氮素再转运速率相关。生殖生长期的~（15）N示踪试验表明，早、晚衰品系中，氮素从叶片向花器官和种子的再转运速率相似。在生殖生长阶段，氮素再动员效率不依赖于衰老表型，而是与库源器官生物量的比值有关。
Five recombinant inbred lines (RILs) of Arabidopsis (Arabidopsis thaliana), previously selected from the Bay-0X Shahdara RIL population on the basis of differential leaf senescence phenotypes ( from early senescing to late senescing) when cultivated under nitrogen ( N)- limiting conditions, were analyzed to monitor metabolic markers related to N assimilation and N remobilization pathways. In each RIL, a decrease of total N, free amino acid, and soluble protein contents with leaf aging was observed. In parallel, the expression of markers for N remobilization such as cytosolic glutamine synthetase, glutamate dehydrogenase, and CND41- like protease was increased. This increase occurred earlier and more rapidly in early-senescing lines than in late-senescing lines. We measured the partitioning of (15) N between sink and source leaves during the vegetative stage of development using (15) N tracing and showed that N remobilization from the source leaves to the sink leaves was more efficient in the early-senescing lines. The N remobilization rate was correlated with leaf senescence severity at the vegetative stage. Experiments of (15) N tracing at the reproductive stage showed, however, that the rate of N remobilization from the rosettes to the flowering organs and to the seeds was similar in early- and late-senescing lines. At the reproductive stage, N remobilization efficiency did not depend on senescence phenotypes but was related to the ratio between the biomasses of the sink and the source organs.