Recent advances in the regulation of histone lysine methylation in plants and the role of this modification in the developmental programming of Arabidopsis are discussed.

The characteristic secondary metabolites in tea (theanine, caffeine, and catechins) are important factors contributing to unique tea flavors. However, there has been relatively little research on molecular markers related to these metabolites. Thus, we conducted a genome-wide association analysis of the levels of these tea flavor-related metabolites in three seasons. The theanine, caffeine, and catechin levels in Population 1 comprising 191 tea plant germplasms were examined, which revealed that their heritability exceeded 0.5 in the analyzed seasons, with the following rank order (highest to lowest heritabilities): (+)-catechin > (−)-gallocatechin gallate > caffeine = (−)-epicatechin > (−)-epigallocatechin-3-gallate > theanine > (−)-epigallocatechin > (−)-epicatechin-3-gallate > catechin gallate > (+)-gallocatechin. The SNPs detected by amplified-fragment SNP and methylation sequencing divided Population 1 into three groups and seven subgroups. An association analysis yielded 307 SNP markers related to theanine, caffeine, and catechins that were common to all three seasons. Some of the markers were pleiotropic. The functional annotation of 180 key genes at the SNP loci revealed that FLS, UGT, MYB, and WD40 domain-containing proteins, as well as ATP-binding cassette transporters, may be important for catechin synthesis. KEGG and GO analyses indicated that these genes are associated with metabolic pathways and secondary metabolite biosynthesis. Moreover, in Population 2 (98 tea plant germplasm resources), 30 candidate SNPs were verified, including 17 SNPs that were significantly or extremely significantly associated with specific metabolite levels. These results will provide a foundation for future research on important flavor-related metabolites and may help accelerate the breeding of new tea varieties.

Jiangxi Congou black tea is one of the earliest Congou black tea in China. In order to explore its sensory characteristics and molecular sensory basis, quantitative description analysis (QDA) and gas chromatography-mass spectrometry (GC-MS) were used to analyze the sensory characteristics and volatile components of 11 Congou black tea samples from Jiangxi Province in China. The results showed that the aroma characteristics of Jiangxi Congou black were composed of 11 aroma descriptors, namely, sweet-smell, floral, fruity, roasted, spicy, fresh, green, oil, off-odor, woody and smoky. There was also interaction effect between sensory attributes of aroma, which were significant negative correlation between floral, and fruity, and green. The presence of roasted incense could significantly enhance the olfactory perception of off-odor and smoky, and off-odor was an important attribute that affects the aroma quality of Jiangxi Congou black tea. Volatile components (i.e. 74 kinds) were identified, among which the highest content and species were alcohols, followed by esters, and the lowest were heterocycles and terpenes. The results of partial least square variable import project (PLS-VIP) showed that there were 29 volatile compounds that had an important contribution to the aroma characteristics of Congou black tea, and the volatile compounds that had an important influence on six aroma attributes were obtained.