Concentrations of Phenolic Acids Are Differently Genetically Determined in Leaves, Flowers, and Grain of Common Buckwheat (Fagopyrum esculentum Moench)

Abstract

Common buckwheat (Fagopyrum esculentum Moench) is a valuable source of proteins, B vitamins, manganese, tryptophan, phytochemicals with an antioxidant effect, and the natural flavonoid rutin. Due to its composition, buckwheat supports the human immune system, regulates blood cholesterol, and is suitable for patients with diabetes or celiac disease. The study aimed to compare the allocation of selected phenolic acids (neochlorogenic acid, chlorogenic acid, trans-caffeic acid, trans-p-coumaric acid, trans-sinapic acid, trans-ferulic acid) and flavonoids (rutin, vitexin, quercetin, kaempferol) in the leaves, flowers, and grain of buckwheat cultivars of different origin. The content of individual phenolics was determined by the HPLC-DAD method. The results confirmed the determining role of cultivar on the relative content of chlorogenic acid, trans-caffeic acid, trans-sinapic acid, vitexin, and kaempferol in buckwheat plants. A significantly negative correlation among concentrations of phenolic acids in different common buckwheat plant parts shows that there are different mechanisms of genetic influences on the concentration of phenolic substances in common buckwheat flowers, leaves, and grain. These differences should be taken into account when breeding buckwheat for a high concentration of selected phenolic substances.

Breeding Buckwheat for Nutritional Quality in the Czech Republic

“…The mean values between years differed and were similar to vitexin, accessions showed higher values of isovitexin in 2020. The obtained results are comparable to the values published by Vollmannova et al [52], who reported 0.010-0.212 mg/g d.w. The content of vitexin in buckwheat grains cultivated in Slovakia, reported the lowest value in the variety 'Ballada' (0.010 mg/g d.w.) but this is not in line with our findings where 'Ballada' had stable and almost six times higher content of vitexin, higher in both experimental years (66.91 ± 1.34 ug/g d.w. for 2019 and 53.50 ug/g d.w. for 2020).…”

“…An unusually high amount of quercetin (66.88 ± 0.58 ug/g d.w.) was detected in ‘Temnica na Krasu’ in 2020. However, this was an exception among all the studied buckwheat samples and the other values observed were more or less at the same level but at a lower level in comparison with data presented by Vollemannová et al [ 52 ]. Quercitrin in the buckwheat collection was found at a level of 3.87 ± 2.66 ug/g d.w. for 2020 and 1.19 ± 0.98 ug/g d.w. for 2019.…”

“…Of the flavanols, the levels of apigenin and kaempferol were also determined, but the levels found were very low. Small amounts of kaempferol were also detected in eight buckwheat varieties cultivated in Slovakia [52], but levels are higher when compared to our data from the Czech Republic. From Slovakia the variety 'Ballada', for example, had from 0.01 to 0.03 ug/g d.w. and 1.438 mg/g d.w. [52].…”

“…Small amounts of kaempferol were also detected in eight buckwheat varieties cultivated in Slovakia [52], but levels are higher when compared to our data from the Czech Republic. From Slovakia the variety 'Ballada', for example, had from 0.01 to 0.03 ug/g d.w. and 1.438 mg/g d.w. [52]. In contrast to our results is the result of HPLC characterization of Chinese buckwheat samples, where apigenin and kaempferol were found at high levels, which could be due to differences in genotypes and environmental factors affecting growth [58].…”

“…The mean value of rutin content in 2020 (224.16 ± 70.66 ug/g d.w.) was higher than in 2019 (186.92 ± 64.18 ug/g d.w.), which is less than the values observed by Kalinova and Vrchotova [ 51 ] and significantly higher than that (0.064 mg/g) obtained during summer cropping in the UK [ 14 ]. On the other hand, rutin content in buckwheat grains cultivated in Slovakia was much higher [ 52 ] and closer to the values more common for Tartary buckwheat seed Borovaya and Klykov [ 53 ] and sprouted seeds [ 54 ]. Surprisingly, the highest rutin content across all accessions was reached by the ‘Nostrano’ accession (819.89 ± 16.66 ug/g d.w.) in 2019, which also showed the highest decrease (by 545.04 ug/g d.w.) in rutin content from 2019 to 2020.…”