Cytokinin-induced changes of nitrogen remobilization and chloroplast ultrastructure in wheat (Triticum aestivum)
Cytokinin-induced changes of nitrogen remobilization and chloroplast ultrastructure in wheat (Triticum aestivum)
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DOI：
10.1016/j.jplph.2009.05.007
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发表时间：
2009-01-01
影响因子：
4.3
通讯作者：
Barneix, Atilio J.
中科院分区：
文献类型：
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作者：
Criado, Maria V.;Caputo, Carla;Barneix, Atilio J.
小麦 (Triticum aestivum) 植物中的氮 (N) 重新利用至关重要，因为它决定了谷物蛋白质浓度和面粉的烘焙质量。为了评估氮饥饿期间细胞分裂素对氮再动员的影响，我们分析了用 6-苄氨基嘌呤 (BAP) 浇灌（含或不含 KNO3）的小麦植株的各种氮再动员参数。此外，还评估了BAP对蛋白质合成的影响，并研究了BAP处理植物叶绿体的大小和超微结构。 BAP 供应独立于氮供应抑制植物的氮再动员，如老叶中蛋白质、Rubisco、叶绿素、糖和淀粉浓度的增加，向韧皮部的氨基酸和糖输出的减少以及年轻叶中蛋白质、Rubisco 和叶绿素浓度的减少所表明的。此外，BAP 供应增加了硝酸盐还原酶活性并降低了硝酸盐浓度，从而表明同化能力增加。蛋白质浓度的增加主要可以通过蛋白质降解的显着减少来解释，并且在较小程度上可以通过蛋白质合成的增加来解释。最后，观察到提供 BAP 的植物中叶绿体大小以及质体球和淀粉含量均有所增加。我们认为细胞分裂素通过抑制氨基酸和糖向韧皮部的输出并刺激老叶叶绿体中同化物的积累来保留老叶的库活性。此外，即使在胁迫条件下，BAP 也可以通过减少蛋白质降解和维持蛋白质合成来增加老叶的蛋白质浓度。 (C) 2009 爱思唯尔有限公司。版权所有。
Nitrogen (N) remobilization in wheat (Triticum aestivum) plants is crucial because it determines the grain protein concentration and the baking quality of flour. In order to evaluate the influence of cytokinins on N remobilization during N starvation, we analyzed various N remobilization parameters in wheat plants that were watered with 6-benzylaminopurine (BAP) either with or without KNO3. Besides, the effects of BAP on protein synthesis were evaluated, and the size and ultrastructure of chloroplasts of BAP-treated plants were studied. BAP supply inhibited N remobilization of plants independently of N supply as shown by the increase in protein, Rubisco, chlorophyll, sugar and starch concentrations in the older Leaves, the decrease in amino acid and sugar export to the phloem, and the decrease in protein, Rubisco and chlorophyll concentrations in the younger leaves. Besides, BAP supply increased nitrate reductase activity and decreased nitrate concentration, thus suggesting an increased assimilatory capacity. The increase in protein concentration could be explained mainly by a significant decrease in protein degradation and, to a lesser extent, by an increase in protein synthesis. Finally, an increase both in the size of the chloroplast and in the plastoglobuli and starch contents in BAP-supplied plants was observed. We propose that cytokinins retain the sink activity of the older leaves by inhibiting amino acid and sugar export to the phloem and stimulating assimilate accumulation in the chloroplasts of the older leaves. Besides, BAP may increase protein concentration of the older leaves both by decreasing protein degradation and maintaining protein synthesis even under stress conditions. (C) 2009 Elsevier GmbH. All rights reserved.