Recently, the team of fruit nutrition and function from Zhengzhou Fruit Research Institute (ZFRI) has illustrated the effects of postharvest UV-C irradiation on biosynthesis and accumulation of flavonoids and anthocyanins in sweet cherries during storage, which is useful for the enhancement of the nutritive value of sweet cherries by postharvest treatments. The results have been published in Postharvest Biology and Technology.

UV-C irradiation is an easy and green treatment for postharvest fruit. It can not only improve the storage quality of fruits, but also enhance the nutritive value of fruits by stimulating the biosynthesis and accumulation of bioactive compounds in postharvest fruits. In this study, sweet cherries (Brooks) were treated with UV-C irradiation (1.05, 2.10, and 4.20 kJ/m2) for different treatment periods, they were stored at room temperature (25.0 ± 2.0 ℃) for 6 days. The results showed that the total phenolics, flavonoids, and anthocyanins increased in response to UV-C during storage. UPLC-ESI-MS analysis indicated that the individual flavonoids and anthocyanins contents increased, including cyanidin 3-O-galactoside, cyanidin O-syringic acid, cyanidin 3-O-glucoside, pelargonidin 3-O-glucoside, tricin 5-O-hexoside, luteolin C-hexoside, Di-O-methylquercetin, and naringenin-7-O-glucoside. Furthermore, UV-C (2.10 kJ/m2) treatment upregulated the enzymes activity and genes expression of phenylpropanoid pathway. Highly significant correlations were found among flavonoids, anthocyanins, phenylalanine ammonia lyase (PAL) and genes expression of ANS, DFR, UFGT (r > 0.6, p < 0.01) and cinnamate 4-hydroxylase (C4H) and PAL, C4H, 4CL, CHI, ANS, DFR expressions (r> 0.6, p < 0.01).

UV-C treatment up-regulated the genes expression of PAL, C4H, 4CL, CHI, ANS, DFR, UFGT, which increased the enzymatic activities of PAL and C4H to promote the accumulation of flavonoids and anthocyanins. These results contribute to illustrating the molecular mechanism of flavonoids and anthocyanins biosynthesis of sweet cherries under the UV-C irradiation and promote the development of postharvest in agriculture.

This work was supported by the Agricultural Science and Technology Innovation Program of Chinese Academy of Agricultural Sciences (CAAS-ASTIP-ZFRI) and the Key science and Technology program of Henan Province (No. 202102110209).

The mechanism of flavonoids and anthocyanin accumulation induced by UV-C treatment

More details are available at the following link:

https://doi.org/10.1016/j.postharvbio.2021.111490

By Zhang Qiang (zhangqiang02@caas.cn)