TY  - JOUR
A1  - Heinze, Mandy
A1  - Hanschen, Franziska S.
A1  - Wiesner-Reinhold, Melanie
A1  - Baldermann, Susanne
A1  - Gräfe, Jan
A1  - Schreiner, Monika
A1  - Neugart, Susanne
T1  - Effects of Developmental Stages and Reduced UVB and Low UV Conditions on Plant Secondary Metabolite Profiles in Pak Choi (Brassica rapa subsp chinensis)
JF  - Journal of agricultural and food chemistry : a publication of the American Chemical Society
N2  - Pak choi (Brassica rapa subsp. chinensis) is rich in secondary metabolites and contains numerous antioxidants, including flavonoids; hydroxycinnamic acids; carotenoids; chlorophylls; and glucosinolates, which can be hydrolyzed to epithionitriles, nitriles, or isothiocyanates. Here, we investigate the effect of reduced exposure to ultraviolet B (UVB) and UV (UVA and UVB) light at four different developmental stages of pak choi. We found that both the plant morphology and secondary metabolite profiles were affected by reduced exposure to UVB and UV, depending on the plant’s developmental stage. In detail, mature 15- and 30-leaf plants had higher concentrations of flavonoids, hydroxycinnamic acids, carotenoids, and chlorophylls, whereas sprouts contained high concentrations of glucosinolates and their hydrolysis products. Dry weights and leaf areas increased as a result of reduced UVB and low UV. For the flavonoids and hydroxycinnamic acids in 30-leaf plants, less complex compounds were favored, for example, sinapic acid acylated kaempferol triglycoside instead of the corresponding tetraglycoside. Moreover, also in 30-leaf plants, zeaxanthin, a carotenoid linked to protection during photosynthesis, was increased under low UV conditions. Interestingly, most glucosinolates were not affected by reduced UVB and low UV conditions. However, this study underlines the importance of 4-(methylsulfinyl)butyl glucosinolate in response to UVA and UVB exposure. Further, reduced UVB and low UV conditions resulted in higher concentrations of glucosinolate-derived nitriles. In conclusion, exposure to low doses of UVB and UV from the early to late developmental stages did not result in overall lower concentrations of plant secondary metabolites.
KW  - flavonoids
KW  - hydroxycinnamic acids
KW  - carotenoids
KW  - glucosinolates
KW  - nitriles
KW  - UVB reduction
Y1  - 2018
U6  - https://doi.org/10.1021/acs.jafc.7b03996
SN  - 0021-8561
SN  - 1520-5118
VL  - 66
IS  - 7
SP  - 1678
EP  - 1692
PB  - American Chemical Society
CY  - Washington
ER  -