Combined analysis of transcriptome and metabolome provides insights into nano-selenium foliar applications to improve summer tea quality (Camellia sinensis)
Xiangxiang Huang, Qian Tang, Chongjun Chen, Qin Li, Haiyan Lin, Silei Bai, Jian Zhao, Juan Li, Kunbo Wang, Mingzhi Zhu
Abstract
Summer tea quality deteriorates with its inferior taste features. Exogenous nano-selenium (Se) supplementation is an effective device to improve crop quality and economic value; however, the effects of nano-Se on summer tea quality remain unclear. This study aimed to illustrate the effects of foliar application of nano-Se on summer tea leaf quality by integrating metabolomics and transcriptomics approaches. Nano-Se enhanced Se content in tea leaves. Further, nano-Se significantly decreased the total tea polyphenols, catechin, and caffeine contents but increased total amino acids and theanine contents, markedly lowering the ratio of tea polyphenols/amino acids as well. Sensory evaluation indicated that nano-Se reduced the bitterness and astringency and improved the umami and sweet tastes of the tea infusion. A total of 130 compounds were identified in the metabolome. Levels of most phenolic compounds were decreased after nano-Se treatment. Association analysis depicted that a total of 30 differentially expressed genes (DEGs) related to catechin (18), caffeine (7), and theanine (5) biosynthetic pathways were influenced by nano-Se. Several transcription factors were identified to interact with these DEGs. Our findings indicate that foliar application of nano-Se can significantly improve summer tea quality, and provide new insight into the application of nano-Se in tea plants.