Flavonoid Glycosides in Brassica Species Respond to UV-B Depending on Exposure Time and Adaptation Time

Abstract

Recently, there have been efforts to use ultraviolet-B radiation (UV-B) as a biotechnological tool in greenhouses. Leafy Brassica species are mainly considered for their ability to synthesize glucosinolates and are valued as baby salads. They also have a remarkable concentration of chemically diverse flavonoid glycosides. In this study, the effect of short-term UV-B radiation at the end of the production cycle was investigated without affecting plant growth. The aim was to verify which exposure and adaptation time was suitable and needs to be further investigated to use UV as a biotechnological tool in greenhouse production of Brassica species. It is possible to modify the flavonoid glycoside profile of leafy Brassica species by increasing compounds that appear to have potentially high antioxidant activity. Exemplarily, the present experiment shows that kaempferol glycosides may be preferred over quercetin glycosides in response to UV-B in Brassica rapa ssp. chinensis, for example, whereas other species appear to prefer quercetin glycosides over kaempferol glycosides, such as Brassica oleracea var. sabellica or Brassica carinata. However, the response to short-term UV-B treatment is species-specific and conclusions on exposure and adaptation time cannot be unified but must be drawn separately for each species.

Metabolomics Reveals Heterogeneity in the Chemical Composition of Green and White Spears of Asparagus (A. officinalis)

“…Using a complementary approach, Yi et al, (2019) performed de novo transcriptome sequencing in both green and white types of a commercial variety (Atlas) and found significant differences between the two asparagus types in that 21% of the genes involved in the biosynthesis of the flavonoid rutin were upregulated in green and 4% of the genes involved in the biosynthesis of the saponin protodioscin were upregulated in white asparagus [ 41 ]. These results followed and confirmed other studies, which focused on quantifying these two compounds in green and white asparagus, as well as other flavonoids and saponins [ 22 , 32 , 39 , 42 , 43 ], suggesting that indeed metabolic pathways are differently active in green and white asparagus shoots.…”

“…For example, higher saponin levels are typical of asparagus roots [ 18 , 38 ] as well as white shoots compared to green ones ( Table 1 ). In this regard, David and Hofmann (2014) [ 39 ] and Lee et al, (2010) [ 22 ] found higher concentrations of saponins in the stem sections closer to the crown/roots of white asparagus, compared to the young asparagus tips.…”

“…For example, Amaro-López (1998) [ 14 ] and Makus (1994) [ 19 ] studied the distribution of important minerals in the green and white asparagus shoots, and Creydt and Fischer (2020) [ 47 ] have recently investigated the distribution of primary metabolites in white asparagus spears. Moreover, Dawid and Hofmann (2014) [ 39 ] have demonstrated a quantitative gradient of asparagus saponins along the white asparagus shoot, while Lee (2010) [ 22 ] and Wang (2003) [ 43 ] have also shown a gradient of protodioscin along asparagus spears. Together, all these complementary observations clearly indicate considerable heterogeneity in metabolite presence within asparagus spears.…”

Altitudinal Variation of Metabolites, Mineral Elements and Antioxidant Activities of Rhodiola crenulata (Hook.f. & Thomson) H.Ohba

“…Some studies have reported an enhanced effect of UV light or low temperature on the biosynthesis of quercetins, condensed tannins and flavonoid glycosides in plants [ 81 , 84 , 85 ]. These substances have a variety of resilient biological activities against UV radiation, low temperature or drought [ 21 , 25 , 26 ], and our results are consistent with these previous findings.…”

Time-Course of Changes in Photosynthesis and Secondary Metabolites in Canola (Brassica napus) Under Different UV-B Irradiation Levels in a Plant Factory With Artificial Light

“…Elevated total phenolic content was observed in highbush blueberry leaves ( Vaccinium corymbosum L. cv. Bluegold) exposed to UV-B for 24 h. In addition, Neugart and Bumke-Vogt (2021) investigated the effects on major genes expression of the phenylpropanoid pathway, contents of the flavonoid groups, and hydroxycinnamic acid derivatives after short-term UV-B irradiation and before the harvest of various Brassica species ( B. rapa, B. nigra, B. oleracea, B. juncea, B. napus , and B. carinata ). The response during the acclimation period after the UV-B irradiation (2 and 24 h) was investigated, but the response immediately after the UV-B irradiation was not confirmed.…”