Excessive nitrogen application dampens antioxidant capacity and grain filling in wheat as revealed by metabolic and physiological analyses

Abstract

In this study, field-grown wheat (Triticum aestivum L.) was treated with normal (Nn) and excessive (Ne) levels of fertilizer N. Results showed that Ne depressed the activity of superoxide dismutase and peroxidase and increased the accumulation of reactive oxygen species (ROS) and malondialdehyde. The normalized difference vegetation index (NDVI) was higher under Ne at anthesis and medium milk but similar at the early dough stage and significantly lower at the hard dough stage than that under Nn. The metabolomics analysis of the leaf responses to Ne during grain filling showed 99 metabolites that were different between Ne and Nn treatments, including phenolic and flavonoid compounds, amino acids, organic acids and lipids, which are primarily involved in ROS scavenging, N metabolism, heat stress adaptation and disease resistance. Organic carbon (C) and total N contents were affected by the Ne treatment, with lower C/N ratios developing after medium milk. Ultimately, grain yields decreased with Ne. Based on these data, compared with the normal N fertilizer treatment, we concluded that excessive N application decreased the ability to scavenge ROS, increased lipid peroxidation and caused significant metabolic changes disturbing N metabolism, secondary metabolism and lipid metabolism, which led to reduced grain filling in wheat.

Therapeutic targeting of cellular stress responses in cancer

“…Reactive oxygen species (ROS), such as superoxide anion radicals, hydroxyl radicals, and hydrogen peroxide, are natural by‐products of aerobic metabolism . In cells, mitochondria are the primary source of endogenous intracellular reactive species.…”

“…Reactive oxygen species (ROS), such as superoxide anion radicals, hydroxyl radicals, and hydrogen peroxide, are natural by-products of aerobic metabolism. [51][52][53][54][55][56][57] In cells, mitochondria are the primary source of endogenous intracellular reactive species. These metabolic intermediates play important roles in physiological functions and signaling pathways, both as effectors and as signaling molecules.…”

Molecular mechanisms underlying stress response and adaptation

“…Changes in expression of these genes decrease intracellular Na + levels and abscisic acid (ABA) contents and increase intracellular K + levels and cytokinin expression . Similar to the effects of NO in cotton, exogenous hydrogen sulfide production enhances salt tolerance by decreasing Na + content in wheat seedlings . During salt acclimation in Arabidopsis thaliana , cell wall remodeling, ethylene biosynthesis, and signaling pathways play crucial roles .…”

Quality and Grain Yield Attributes of Rwandan Rice (Oryza sativaL.) Cultivars Grown in a Biotron Applying Two NPK Levels

“…Yu et al [68] observed that grain content of N, P, and K increased with an increasing nitrogen supply up to 270 kg·hm −2 but decreased above this dose. Furthermore, excessive nitrogen fertilization was associated with a reduction in antioxidant capacity in wheat grains [69]. Nguyen and Niemeyer [70] reported a reduction of phenolic acids content and antioxidant capacity in basil at a high rate of nitrogen fertilizer.…”