Genotype‐dependent changes in the phenolic content of durum under water‐deficit stress

Abstract

Background and objectives Consumption of whole grain cereal products, which are rich in phenolic acids, is associated with lower risk of degenerative diseases. Phenolics in plants are associated with abiotic stress adaptation due to their antioxidant activities. Free, bound, and total phenolics in the wholemeal flour of 50 durum wheat (Triticum turgidum L. ssp. durum) genotypes were examined, in addition to the water stress tolerance capacity of selected genotypes. Findings This study revealed significant variation, with wholemeal flour from “Purple Grain” having the highest total phenolic content (391.0 mg gallic acid equivalent per 100 g of dry weight [GAE/100 g DW]). Under water‐deficit stress, the stress‐tolerant genotype Tamaroi had higher total phenolic content in the leaf (2880.3 mg GAE/100 g DW) compared to stress‐sensitive genotypes EGA Bellaroi and Tjilkuri (2292.6 and 2450.1 mg GAE/100 g DW, respectively). In the mature grains, stress‐tolerant genotypes Tamaroi and Yawa had significantly higher total phenolic content under stress compared to the control, while no significant change was found in the stress‐sensitive genotypes EGA Bellaroi and Tjilkuri. Conclusions Results suggest that phenolic content could be associated with water‐deficit stress tolerance. Significance and novelty Selected genotypes could now be used as parents for breeding varieties with increased phenolics and stress tolerance capacity.

Biological role and health benefits of antioxidant compounds in cereals

“…For example, droughtresistant durum wheat cultivars manifested higher levels of phenols in their leaves under drought conditions than susceptible genotypes. The content of phenolic compounds in maturing kernels of drought-resistant cultivars was much higher under stressor conditions than in control conditions Liu et al, 2018). Besides, antioxidant activity correlates with the resistance of plants to Fusarium pathogens and heavy metal ions .…”

“…Whole-grain groats of cereal crops are a good source of many antioxidants, having a high antioxidative potential in vitro: vitamin E, folic acid, phenolic compounds, carotenoids, phytic acid, zinc, iron and selenium (Adom and Liu, 2002;Fardet, 2010;Xu et al, 2016;Liu et al, 2018). The whole grain of wheat or barley is known to be a rich source of bioactive phytochemical compounds, such as phenolic acids, carotenoids, tocopherols, flavonoids, alkylresorcinols, phytosterols and lignans (Luthria et al, 2015).…”

“…Antioxidant activity was assessed in different fractions of the milled grain of durum and bread wheat cultivars. It appeared that with the rising of the milling degree this activity considerably decreased, and the highest antioxidant activity was registered in the 10-20 % milling fraction (Liyana-Pathirana et al, 2006). The grain of covered barley cultivars was gradually dehulled, and 5 % of its weight was removed with each of the eight processing cycles.…”

“…Since phenolics concentrate in outer layers, bran obtained from grain processing may be used as a natural source of antioxidants and as a value-adding product for functional food ingredient production (Liyana-Pathirana et al, 2006). Today, cereal bran, a by-product of grain processing, has won a crucial status in functional food recipes.…”

“…The content of free, bound and total phenolics was assessed in the whole-grain flour of durum wheat cultivars, and the ability of the plants to survive water stress was analyzed. Under water deficit, the grain of the stress-resistant genotypes 'Tamaroi' and 'Yawa' demonstrated higher content of phenolic compounds than the reference, while the stress-sensitive genotypes 'Bellaroi' and 'Tjilkuri' showed no significant changes (Liu et al, 2018). Cavallero et al (2004) studied the effect of the genotype and the place of cultivation on the amount of tocols in covered and naked barley grain and found out that covered barley accumulated higher amounts of these bioactive compounds.…”