Influence of nitrogen deficiency on senescence and the amounts of RNA and proteins in wheat leaves
Influence of nitrogen deficiency on senescence and the amounts of RNA and proteins in wheat leaves
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DOI：
10.1034/j.1399-3054.1998.1020206.x
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发表时间：
1998-02-01
影响因子：
6.4
通讯作者：
Feller, U
中科院分区：
文献类型：
--
作者：
Crafts-Brandner, SJ;Hölzer, R;Feller, U
研究了小麦幼体叶片中不同细胞区室酶含量的衰老相关协调性。Arina)植物。衰老开始于完全lear伸长时，基于总RNA和可溶性蛋白的下降。在叶片完全伸长时从生长培养基中去除氮素可提高植株的衰老速度。在叶片完全伸长后，核酮糖-1,5-二磷酸羧化酶/加氧酶（Rubisco, EC 4.1.1.39）的数量持续下降，红细胞转录物显著减少，表明Rubisco的合成/降解对衰老的发生非常敏感。Rubisco激活酶的数量在衰老过程中也有所下降，但rea转录物相对于总聚A RNA库的比例在衰老过程中增加了3倍。因此，激活酶的持续合成可能需要在整个衰老过程中维持Rubisco的功能。氮胁迫导致叶绿体、过氧化物酶体和细胞质中蛋白质的数量下降。Clp蛋白酶亚基的转录本也在氮胁迫下下降，这表明Clp不是一种衰老特异性蛋白酶。与其他蛋白质相比，线粒体nadh -谷氨酸脱氢酶（EC 1.4.1.2）在衰老过程中相对稳定，不受氮胁迫的影响。在自然衰老期间，在植物硝酸盐供应充足的情况下，丁腈还原酶（EC 1.7.7.1）的数量增加，谷氨酰胺合成酶（EC 1.4.7.1）和谷氨酸合成酶（EC 6.3.1.2）的数量保持稳定。这些结果表明，如果维持底物供应，衰老过程中氮的吸收能力可以继续甚至增加。即使在同一个细胞区室中，表明衰老过程中的蛋白质水解活性必须受到高度调节。
Senescence-associated coordination in amounts of enzymes localized in different cellular compartments were determined in attached leaves of young wheat (Triticum aestivum L. cv. Arina) plants. Senescence was initiated at the time of full lear elongation based on declines in total RNA and soluble protein. Removal of N from the growth medium just at the time of full leaf elongation enhanced the rate of senescence. Sustained declines in the amount of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco, EC 4.1.1.39), and a marked decrease in the rbcS transcripts, just after full leaf elongation indicated that Rubisco synthesis/degradation was very sensitive to the onset of senescence. Rubisco activase amount also declined during senescence but the proportion of rea transcript relative to the total poly A RNA pool increased 3-fold during senescence. Thus, continued synthesis of activase may be required to maintain functional Rubisco throughout senescence. N stress led to declines in the amount of proteins located in the chloroplast, the peroxisome and the cytosol. Transcripts of the Clp protease subunits also declined in response to N stress, indicating that Clp is not a senescence-specific protease. In contrast to the other proteins, mitochondrial NADH-glutamate dehydrogenase (EC 1.4.1.2) was relatively stable during senescence and was not affected by N stress. During natural senescence with adequate plant nitrate supply the amount of nitrile reductase (EC 1.7.7.1) increased, and those of glutamine synthetase (EC 1.4.7.1) and glutamate synthase (EC 6.3.1.2) were stable. These results indicated that N assimilatory capacity can continue or even increase during senescence if the substrate supply is maintained, Differential stabilities of proteins. even within the same cellular compartment, indicate that proteolytic activity during senescence must be highly regulated.