Sahay Seema, Robledo-Arratia Luis, Glowacka Katarzyna, Gupta Meetu
Ecotoxicogenomics Lab, Department of Biotechnology, Jamia Millia Islamia, New Delhi, 110025, India.
Departamento de Biología, Instituto Nacional de Investigaciones Nucleares (ININ), Ocoyoacac, C.P. 52750, México.
Sci Rep. 2021 Apr 12;11(1):7992. doi: 10.1038/s41598-021-86401-0.
Little is known about the interactive effects of exogenous nitric oxide (NO) and abscisic acid (ABA) on nitrogen (N) metabolism and related changes at molecular and biochemical levels under drought stress. The present study highlights the independent and combined effect of NO and ABA (grouped as "nitrate agonists") on expression profiles of representative key genes known to be involved in N-uptake and assimilation, together with proline metabolism, N-NO metabolism enzyme's activity and nutrient content in polyethylene glycol (PEG) treated roots of Indian mustard (B. juncea cv. Varuna). Here we report that PEG mediated drought stress negatively inhibited growth performance, as manifested by reduced biomass (fresh and dry weight) production. Total N content and other nitrogenous compounds (NO, NO) were decreased; however, NH, NH/ NO ratio and total free amino acids content were increased. These results were positively correlated with the PEG induced changes in expression of genes and enzymes involved in N-uptake and assimilation. Also, PEG supply lowered the content of macro- and micro-nutrients but proline level and the activity of ∆-pyrroline-5-carboxylate synthetase increased indicating increased oxidative stress. However, all these responses were reversed upon the exogenous application of nitrate agonists (PEG + NO, PEG + NO + ABA, and PEG + ABA) where NO containing nitrate agonist treatment i.e. PEG + NO was significantly more effective than PEG + ABA in alleviating drought stress. Further, increases in activities of L-arginine dependent NOS-like enzyme and S-nitrosoglutathione reductase were observed under nitrate agonist treatments. This indicates that the balanced endogenous change in NO and ABA levels together during synthesis and degradation of NO mitigated the oxidative stress in Indian mustard seedlings. Overall, our results reveal that NO independently or together with ABA may contribute to improved crop growth and productivity under drought stress.
关于干旱胁迫下外源一氧化氮（NO）和脱落酸（ABA）对氮（N）代谢以及分子和生化水平相关变化的交互作用，目前所知甚少。本研究着重探讨了NO和ABA（归为“硝酸盐激动剂”组）对已知参与氮吸收和同化的代表性关键基因的表达谱的独立和联合作用，以及脯氨酸代谢、N-NO代谢酶活性和聚乙二醇（PEG）处理的印度芥菜（B. juncea cv. Varuna）根系中的养分含量。在此我们报告，PEG介导的干旱胁迫对生长性能产生了负面抑制，表现为生物量（鲜重和干重）产量降低。总氮含量和其他含氮化合物（NO、NO）减少；然而，NH、NH/NO比值和总游离氨基酸含量增加。这些结果与PEG诱导的参与氮吸收和同化的基因和酶表达变化呈正相关。此外，PEG处理降低了大量和微量营养素的含量，但脯氨酸水平和∆-吡咯啉-5-羧酸合成酶的活性增加，表明氧化应激增强。然而，外源施用硝酸盐激动剂（PEG + NO、PEG + NO + ABA和PEG + ABA）后，所有这些反应都得到了逆转，其中含NO的硝酸盐激动剂处理即PEG + NO在缓解干旱胁迫方面比PEG + ABA显著更有效。此外，在硝酸盐激动剂处理下观察到L-精氨酸依赖性一氧化氮合酶样酶和S-亚硝基谷胱甘肽还原酶的活性增加。这表明在NO的合成和降解过程中，NO和ABA水平的内源性平衡变化共同减轻了印度芥菜幼苗的氧化应激。总体而言，我们的结果表明，NO单独或与ABA一起可能有助于提高干旱胁迫下作物的生长和生产力。
