Dynamics of antioxidant properties, phenolic compounds, and transcriptional expression of key enzymes for the phenylpropanoid pathway in leaves of field‐grown winter wheat with different nitrogen fertilization schemes

Abstract

Wheat is a field crop with high relevance for food production worldwide. An adequate supply with nitrogen (N) is crucial for the grain yield and grain quality of wheat. However, little is known about the influence of N fertilization on phenolic compounds, such as phenolic acids and flavonoids, in the leaves of wheat (Triticum aestivum L. ssp. aestivum cv. Genius) under field conditions. Therefore, a field experiment was set up with winter wheat grown under different N fertilization regimes to investigate the influence of N supply on antioxidant properties in general as well as on distinct phenolic acids and flavonoids in the leaves of wheat plants. In the present study, total phenolic concentration and antioxidant capacity were negatively influenced by higher dosages of N fertilizer. Antioxidant properties were mainly determined by chlorogenic acid and homoorientin, a phenolic acid and a flavonoid, respectively. The production of these phenolic compounds was not limited by the gene transcription of phenylalanine ammonia lyase or cinnamate 4‐hydroxylse, the key enzymes of the phenylpropanoid pathway, since the transcription of these enzymes was not significantly influenced by N fertilization.

Sensitivity of Chinese Hickory to Soil Acidification and Important Plant Metabolites in Response to Soil Acidification

“…The content of CGA in the chrysanthemum is inversely proportional to the amount of nitrogen fertilizer. With the increase in nitrogen fertilizer, the activity of phenylalanine ammonia-lyase (PAL) which is a key enzyme in the phenylpropanoid biosynthesis pathway decreased significantly [36,37]. Therefore, CGA and catechin may be important disease-resistant substances to prevent canker disease and root-rot disease.…”

Actinidia arguta Leaf as a Donor of Potentially Healthful Bioactive Compounds: Implications of Cultivar, Time of Sampling and Soil N Level

“…This may have been a response to drought stress or light intensity. Changes in the capacity of the antioxidant apparatus due to abiotic stresses have frequently been described [32,35,36]. In contrast to the tests described above, DPPH decreased significantly in the corresponding period of time.…”

“…The accumulation of phenolic compounds in plant tissues is often negatively affected by high N nutrition [12,32,46]. An inverse relationship between N availability and the concentration of phenolic compounds not restricted to a specific developmental stage or cultivation method has recently been reported in the leaves of cereals [32]. Plants grown under stress conditions often produce and accumulate phenolic stress metabolites.…”

“…Plants grown under stress conditions often produce and accumulate phenolic stress metabolites. Ndeficient plants suffer from light stress due to their limited photosynthetic capacity, and unfertilised plants are more stressed by an excess of light energy and need to accumulate more antioxidants to prevent photodamage [32,59]. An increase in N level as a signal for the downregulation of genes encoding for enzymes involved in the phenylpropanoid metabolism has been described for tobacco [60].…”

“…Recent research undertaken on kiwiberry provides valuable information on the potential leaf quali-quantitative distribution pattern of phenolics and leaf biological activity, however, no consideration has been given to cultivar differences or other factors [17,19]. There are numerous reports of pre-harvest and post-harvest factors affecting plant bioactive compounds and plant tissue biological activity, which in effect can lead to a different quality of the final bioproducts [8,26,[29][30][31][32]. It would appear that all these factors should be of special interest since the leaves of fruit plants are not a food item or food additive in the classic understanding of these, and factors affecting leaf quality should be acknowledged in detail.…”