Changes in Non-Volatile and Volatile Metabolites Associated with Heterosis in Tea Plants (Camellia sinensis)

Heterosis
or hybrid vigor is extensively used in plant breeding.
However, the contribution of metabolites to heterosis is still elusive.
Here, we systematically identified the non-volatile and volatile metabolites
of two hybrids and their parents in Camellia sinensis. The metabolomics analysis showed prevalent non-additive accumulation
in hybrids, among which the non-additive nucleotides, alkaloids, organic
acids, and tannins contribute to the positive heterosis of hybrids,
including typical inosine, guanosine, adenosine, caffeine, succinic
acid, adipic acid, xylonic acid, and gallic acid. The catechins and
free amino acids in hybrids showed negative heterosis compared to
its maternal cultivar TGY. Furthermore, the significant accumulation
of non-additive terpenes combined with the mild heterosis of other
types of volatiles contributes to the aroma of tea plant hybrids.
The genetics of volatiles from different parents affect the aroma
of hybrids processed into oolong tea. The comprehensive heterosis
of these non-additive metabolites may play an important role in the
formation of desirable breeding traits for hybrids. Our results provide
insights into the utilization of heterosis breeding and the regulation
of heterosis metabolites in tea plants.