Jianghua)

Background

Jianghua Kucha (JHKC) is a special tea germplasm with enriched specialized secondary metabolites, including theacrine, non-epimeric flavanols and methylated flavanols. Moreover, primary metabolites provide precursors and energy for the production of secondary metabolites. However, the accumulation patterns of primary and secondary metabolites in different tissues of JHKC are unclear.

Methods

The changes of primary and secondary metabolites and related metabolic pathways (primary and secondary metabolism) in different JHKC tissues (the bud, 1st-4th leaves, and new stem) were investigated via metabolomics analysis with ultra-high-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UHPLC-QTOF/MS).

Results

Significant differences were observed in 68 primary and 51 secondary metabolites mainly related with the pathways of starch and sucrose, amino acids, caffeine, and flavanols metabolism and TCA cycle. The bud exhibited higher levels of glucose-6-phosphate, citric acid, most amino acids, theobromine, catechin-gallate, epicatechin-gallate, procyanidins, and theasinensins; the 1st leaf showed higher levels of caffeine and epigallocatechin-3-gallate; and the 4th leaf contained higher levels of most monosaccharides, theacrine, and epigallocatechin-3-O-(3"-O-methyl)-gallate. In addition, primary metabolites and important secondary metabolites had certain correlations.

Conclusion

This study provides comprehensive insight into primary and secondary metabolites in JHKC and offers guidelines for efficiently utilizing specialized metabolites of JHKC in the future.

Jianghua)

Jianghua Kucha (JHKC) is a special tea germplasm with high bitterness growing in China; however, the chemical characteristics of JHKC are not completely understood. In this study, 61 differential metabolites were identified between 11 wild JHKC individuals and 3 control cultivars of Fudingdabai, Yunkang 10, and Zhuyeqi using comprehensive nontargeted and targeted metabolomics approach. The JHKC accessions mainly possessed significantly higher levels of purine alkaloids of theacrine (12.06 ± 5.23 mg/g) and 1,3,7-trimethyluric acid, non-epi-form flavanols (catechin, gallocatechin, catechin gallate, and gallocatechin gallate), and methylated flavanols of epigallocatechin-3-O-(3″-O-methyl)-gallate (4.79 ± 1.45 mg/g) and epicatechin-3-O-(3″-O-methyl)-gallate (1.02 ± 0.34 mg/g), as well as significantly lower levels of flavonol glycosides, which indicated that caffeine metabolism, flavonoid biosynthesis, and flavonol and flavone biosynthesis are mostly differential metabolic pathways. Our study demonstrated that JHKC germplasm is a promising resource for breeding novel tea cultivars with high contents of theacrine, non-epi-form flavanols, and methylated flavanols.