Carotenoids accumulation and transcript profiling of carotenoid biosynthesis and degradation genes in new shoots and mature leaves of tea plants

Carotenoids play a significant role in the growth, development, color, and aroma quality of tea plants. The molecular mechanism underlying carotenoid metabolism in tea plants remain to be elucidated. In this study, we determined the carotenoid contents in three tea cultivars (‘Suchazao’, ‘Huangjinya’, and ‘Zhongbai 4’) and conducted transcriptome sequencing on the new shoots and mature leaves of these cultivars. Our results indicated that lutein was the predominant carotenoid in ‘Suchazao’ and ‘Zhongbai 4’, whereas β-carotene was the predominant carotenoid in ‘Huangjinya’. The mature leaves of all three tea cultivars contained higher carotenoids levels compared to the new shoots. In the transcriptome analysis, we identified 24 and 20 key DEGs involved in carotenoid biosynthesis and degradation, respectively. Expression analysis and correlation analysis indicated that CsPSY, CsPDS, CsZDS, CsLCYE, CsLCYB, CsBCH, CsCYP97A3, CsZEP, CsOR, CsCCD1.2, and CsCCD4 play crucial roles in the carotenoid metabolism in tea plants. Furthermore, several transcription factors, including CsMYB59-LOC114278066 and CsNAC56-LOC114260089, were identified in pairwise comparisons, implying their potential role in carotenoid accumulation. These results elucidated carotenoid accumulation patterns in new shoots and mature leaves of three tea cultivars with different leaf colors. It also provided insights into the molecular mechanism that regulate carotenoid accumulation in tea plants.