Arias-Baldrich Cirenia, de la Osa Clara, Bosch Nadja, Ruiz-Ballesta Isabel, Monreal José A, García-Mauriño Sofía
Departamento de Biología Vegetal y Ecología, Facultad de Biología, Universidad de Sevilla, Avenida Reina Mercedes n° 6, 41012 Seville, Spain.
Departamento de Biología Vegetal y Ecología, Facultad de Biología, Universidad de Sevilla, Avenida Reina Mercedes n° 6, 41012 Seville, Spain; Department of Molecular Genetics, Centre for Research in Agricultural Genomics (CRAG), Campus UAB Bellaterra (Cerdanyola del Vallès), 08193 Barcelona, Spain.
J Plant Physiol. 2017 Jul;214:39-47. doi: 10.1016/j.jplph.2017.03.020. Epub 2017 Mar 31.
Sorghum plants grown with 5mM (NH)SO showed symptoms of stress, such as reduced growth and photosynthesis, leaf chlorosis, and reddish roots. Phosphoenolpyruvate carboxylase (PEPC) activity, by supplying carbon skeletons for ammonium assimilation, plays a pivotal role in tolerance to ammonium stress. This work investigated the effect of ammonium nutrition on PPC and PPCK gene expression, on PEPC activity, and on post-translational modifications (PTMs) of PEPC in leaves and roots of sorghum plants. Ammonium increased PEPC kinase (PEPCk) activity and the phosphorylation state of PEPC in leaves, both in light and in the dark, due to increased PPCK1 expression in leaves. This result resembled the effect of salinity on sorghum leaf PEPC and PEPCk, which is thought to allow a better functioning of PEPC in conditions that limit the income of reduced C. In roots, ammonium increased PEPC activity and the amount of monoubiquitinated PEPC. The first effect was related to increased PPC3 expression in roots. These results highlight the relevance of this specific isoenzyme (PPC3) in sorghum responses to ammonium stress. Although the role of monoubiquitination is not fully understood, it also increased in germinating seeds along with massive mobilization of reserves, a process in which the anaplerotic function of PEPC is of major importance.
用5mM硫酸铵培养的高粱植株出现了胁迫症状,如生长和光合作用减弱、叶片黄化以及根系发红。磷酸烯醇式丙酮酸羧化酶(PEPC)通过为铵同化提供碳骨架,在耐铵胁迫中起关键作用。本研究调查了铵营养对高粱植株叶片和根系中PPC和PPCK基因表达、PEPC活性以及PEPC翻译后修饰(PTM)的影响。由于叶片中PPCK1表达增加,铵增加了叶片中PEPC激酶(PEPCk)的活性以及PEPC在光照和黑暗条件下的磷酸化状态。这一结果类似于盐度对高粱叶片PEPC和PEPCk的影响,据认为这使得PEPC在限制还原态碳输入的条件下能更好地发挥作用。在根系中,铵增加了PEPC活性和单泛素化PEPC的量。第一个效应与根系中PPC3表达增加有关。这些结果突出了这种特定同工酶(PPC3)在高粱对铵胁迫反应中的相关性。虽然单泛素化的作用尚未完全了解,但在种子萌发过程中随着储备物质的大量动员它也会增加,在这个过程中PEPC的回补功能至关重要。