The Chrysanthemum morifolium -carotene hydroxylase gene CmBCH1 promotes tolerance to high light by enhancement of the xanthophyll cycle

The xanthophyll cycle is of significant importance in protecting plants against membrane peroxidation induced by intense light exposure. According to our prior investigations, the overexpression of Chrysanthemum morifolium beta-carotene hydroxylase resulted in the synthesis of zeaxanthin in Arabidopsis thaliana. In this study, 240 differ-entially expressed genes associated primarily with the respiratory chain, lipid metabolism, antioxidant activity, and flavonoid metabolism were identified via transcriptomic analysis. Several genes involved in the scavenging of reactive oxygen species and genes encoding antioxidants, including superoxide dismutase, peroxidase, and carotenoids, were found to be upregulated via cluster analysis. In comparison to the wild-type, increased CmBCH1 expression stimulated the expression of zeaxanthin epoxidase (ZEP) and de-epoxidase (VDE), resulting in a substantial accumulation of xanthophyll, zeaxanthin, chlorophylls, and anthocyanins. This observation implies that the CmBCH1 gene has the potential to directly regulate the xanthophyll cycle. The study revealed that the BCH1 gene had more pronounced impacts on photosynthetic and fluorescence parameters, as well as pigments, compared to the light factor. Additionally, there was evidence of an interaction between these two factors. The findings of this study demonstrate that the overexpression of BCH1 in transgenic plants provides enhanced tolerance to intense light stress. Moreover, they offer a genetic engineering approach to improve the tolerance of plants towards high light conditions.