Effect of blue LED light irradiation on chlorophyll metabolism in the flavedo of Valencia orange

Regreening is a phenomenon that mature citrus fruit regain green color accompanied with the accumulation of chlorophylls when left on tree till late spring or summer.
In the present study, to investigate the effect of blue LED light irradiation on chlorophyll metabolism in citrus fruit during regreening, we cultured the flavedo of Valencia orange (Citrus sinensis Osbeck) in vitro under 50 µmol m^‑2 s^‑1 blue LED light (470 nm) for four weeks at 25°C. The results showed that the color of the flavedo in the blue LED light treatment turned from orange to green gradually, while the flavedo in the control remained orange during the experimental period.
Compared with the control, chlorophyll a, chlorophyll b, and total chlorophylls contents were increased by the blue LED light treatment at the 4^th week.
In addition, microarray analysis results showed that the expression of chlorophyll biosynthetic genes (CitHEMA1, CitHEMC, CitHEME1, CitCHLI2, CitGUN4, CitCHLM, CitCHL27, CitPORA, CitCAO, and CitGGDR) was upregulated by the blue LED light treatment.
Under the blue LED light treatment, the high expression of chlorophyll biosynthetic genes led to chlorophyll accumulation in the flavedos in vitro.
These results indicated that blue LED light was an important factor for regulating chlorophyll accumulation and inducing regreening in the flavedo of Valencia orange.

V Asia Symposium on Quality Management in Postharvest Systems

H. Mochizuki, Y. Kitaya, G. Ma, L.C. Zhang, M. Yahata, M. Kato

blue LED light, chlorophyll, citrus, microarray, regreening

https://doi.org/10.17660/ActaHortic.2022.1336.16