Low temperature effects on carotenoids biosynthesis in the leaves of green and albino tea plant (Camellia sinensis (L.) O. Kuntze)

Abstract

Tea plant (Camellia sinensis (L.) O. Kuntze) is one of the most important economic crops worldwide, and it has a positive effect on human health. The low temperature in late autumn and early/late spring cold often cause damage to the normal physiological activities of tea plant, thereby reducing the quality and yield of tea. As one of the essential pigment of higher plant, carotenoids play an important role in the physiological activities of higher plant. In addition, as an important precursor of tea aroma volatiles, carotenoids are the important factors involved in the formation of tea quality. In this study, the main carotenoids, lutein and β-carotene, in leaves of common green tea cultivar 'Longjing 43′ and albino tea cultivar 'White leaf No.1′ were detected after low temperature treatment at 4 ℃. The results showed that the contents of lutein and β-carotene in 'Longjing 43′ were higher than that in 'White leaf No.1′, respectively. The chlorophyll content in two tea cultivars decreased and was significant positive correlation with two kinds of carotenoid content at low temperature. Under low temperature, the genes related to the biosynthesis pathway of methylerythritol 4-phosphate (MEP) and carotenoids all showed varying degrees of response with the changes of lutein and β-carotene content. The relative expression levels of CsDXS1, CsPSY1 and CsCHXB were up-regulated and higher than other related genes. Expression analysis of carotenoids biosynthesis genes and its correlation with carotenoids accumulation confirmed the regulatory role of structural genes in tea plant at low temperature. Promoter prediction results showed that the CsDXR, CsHDS1 and CsCHXB contain low-temperature response element LTR. This study provides reference for further study on the dynamic changes of carotenoids during the growth of tea plant.