...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Plant and Soil >Ammonium assimilation in root nodules of actinorhizal Discaria trinervis. Regulation of enzyme activities and protein levels by the availability of macronutrients (N, P and C)
【24h】

Ammonium assimilation in root nodules of actinorhizal Discaria trinervis. Regulation of enzyme activities and protein levels by the availability of macronutrients (N, P and C)

机译：放线菌圆盘菌根结节中的氨同化。通过提供大量营养素（氮，磷和碳）调节酶活性和蛋白质水平

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Asparagine was found to be the main N compound exported from Discaria trinervis nodules. Aspartate (Asp), glutamate (Glu), alanine (Ala) and serine (Ser) were also detected in root xylem sap, but at lower concentrations. A comparable picture is found in nodulated alfalfa. We hypothesized that a similar set of enzymes for Asn synthesis was present in D. trinervis nodules. We demonstrate the expression of most of the enzymes involved in the synthesis of Asn from NH+ 4 and oxoacids, in nodules – but not in roots – of fully symbiotic D. trinervis. By complementation of enzyme assays (A) and immunodetection (I) we detected glutamane-synthetase (GSA, I), Asp-aminotransferase (AATA), malate-dehydrogenase (MDHA, I, at least two isoforms), Glu-dehydrogenase (GDHA), Glu-synthase (GOGATI) and Asn-synthetase (ASI). PEP-carboxylase (PEPC) activity was not detected. We previously shown that N acts as a negative regulator of nodulation and nodule growth, while P is a strong stimulator for nodule growth. We present data on the regulation of nodule N metabolism by altering, during 4 weeks, the availability of N, P and light in symbiotic D. trinervis. NH4NO3 (2 mM) induced inactivation and degradation of nodule GS, MDH and AS, but activation of GDH and AAT; the amount of nitrogenase components was not affected. A 10-fold increase in P supply did not greatly affect activity and amount of enzymes, suggesting that N metabolism is not P-limited in nodules. On the other hand, suppression of P supply induced an important reduction of nodule GS, GOGAT, MDH and AS protein levels, although nitrogenase was not affected. GDH was the only measured activity that was stimulated by limiting P supply. Shading plants did result in complete degradation of nitrogenase and partial degradation of GS, AS and nodule-specific MDH isoform, but GDH and AAT were activated. These results are discussed in connection with the regulation of nodulation and nodule growth in D. trinervis.
机译：发现天冬酰胺是从圆盘菌结节出口的主要N化合物。在根木质部树液中也检测到了天冬氨酸（Asp），谷氨酸（Glu），丙氨酸（Ala）和丝氨酸（Ser），但浓度较低。在结瘤的苜蓿中发现了类似的图片。我们假设D. trinervis结节中存在一组类似的Asn合成酶。我们证明了与NH + 4 和含氧酸合成Asn的大多数酶在完全共生的D. trinervis的结节中而不在根中的表达。通过酶联免疫吸附试验（A ）和免疫检测（I ）的补充，我们检测到了谷氨酰胺合成酶（GSA，I ），Asp-氨基转移酶（AATA ），苹果酸脱氢酶。 （MDHA，I ，至少两种同工型），Glu-脱氢酶（GDHA ），Glu-合酶（GOGATI ）和Asn合成酶（ASI ）。未检测到PEP羧化酶（PEPC）活性。我们先前表明，N充当结节和结节生长的负调节剂，而P是结节生长的强大刺激剂。我们通过改变共生D. trinervis中的N，P和光的可用性，在4周内改变结节N代谢的调控数据。 NH4 NO3 （2 mM）诱导结节GS，MDH和AS失活和降解，但激活了GDH和AAT。固氮酶成分的量不受影响。磷的供应增加了10倍，并没有极大地影响酶的活性和数量，这表明结节中的氮代谢不受磷的限制。另一方面，尽管固氮酶不受影响，但抑制磷的供应会导致结节GS，GOGAT，MDH和AS蛋白水平显着降低。 GDH是唯一通过限制P供给而刺激的活动。遮荫植物确实导致了固氮酶的完全降解以及GS，AS和根瘤特异性MDH亚型的部分降解，但是GDH和AAT被激活了。讨论了这些结果，并与D. trinervis中的根瘤和根瘤生长调控有关。

著录项

相似文献

  • 外文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号