Genome-Wide Analysis of Nuclear factor-YC Genes in the Tea Plant (Camellia sinensis) and Functional Identification of CsNF-YC6.

Nuclear factor Y (NF-Y) is a class of transcription factors consisting of NF-YA, NF-YB and NF-YC subunits, which are widely distributed in eukaryotes. The NF-YC subunit regulates plant growth and development and plays an important role in the response to stresses. However, there are few reports on this gene subfamily in tea plants. In this study, nine CsNF-YC genes were identified in the genome of 'Longjing 43'. Their phylogeny, gene structure, promoter cis-acting elements, motifs and chromosomal localization of these gene were analyzed. Tissue expression characterization revealed that most of the CsNF-YCs were expressed at low levels in the terminal buds and at relatively high levels in the flowers and roots. CsNF-YC genes responded significantly to gibberellic acid (GA) and abscisic acid (ABA) treatments. We further focused on CsNF-YC6 because it may be involved in the growth and development of tea plants and the regulation of response to abiotic stresses. The CsNF-YC6 protein is localized in the nucleus. Arabidopsis that overexpressed CsNF-YC6 (CsNF-YC6-OE) showed increased seed germination and increased root length under ABA and GA treatments. In addition, the number of cauline leaves, stem lengths and silique numbers were significantly higher in overexpressing Arabidopsis lines than wild type under long-day growth conditions, and CsNF-YC6 promoted primary root growth and increased flowering in Arabidopsis. qPCR analysis showed that in CsNF-YC6-OE lines, flowering pathway-related genes were transcribed at higher levels than wild type. The investigation of the CsNF-YC gene has unveiled that CsNF-YC6 plays a pivotal role in plant growth, root and flower development, as well as responses to abiotic stress.

Dynamic changes in the diversity and function of bacterial community during black tea processing.

Among all types of tea, black tea is produced in the largest amount worldwide, and its consumption is still increasing. Enzymatic fermentation is considered majorly contribute to quality formation of black tea, and the information about the roles of bacterial community in black tea processing is scarce. This study aimed to analyze the dynamic changes in composition, structure, and function of microbial communities during black tea processing and reveal the roles of bacterial community in black tea processing. Results showed that the genera Sphingomonas and Variovorax were dominant throughout the processing of black tea. Prediction function analysis of bacterial community showed that the mean proportions of glucuronoarabinoxylan endo - 1,4 - beta - xylanase, aminopeptidase B, phosphoserine phosphatase, homoserine O-acetyltransferase, glycolysis related enzymes, pyruvate dehydrogenase, tricarboxylic acid cycle related enzymes, and glyoxylate bypass were significantly elevated in the rolling and fermentation stages. The contents of amino acids, soluble sugar, theaflavins, thearubigins, and theabrownins increased greatly during the rolling and fermentation processes. Redundancy and Pearson's correlation analyses showed that the relative abundance of bacteria was closely related to the contents of water extract, tea polyphenols, epigallocatechin, epicatechin gallate, catechin gallate, thearubigins, theaflavins, and theabrownins. Overall, the findings provided new insights into the variation of bacterial community during black tea processing and improved our understanding of the core functional bacteria involved in black tea processing.

The Dark-Purple Tea Cultivar 'Ziyan' Accumulates a Large Amount of Delphinidin-Related Anthocyanins.

Recently, we developed a novel tea cultivar 'Ziyan' with distinct purple leaves. There was a significant correlation between leaf color and anthocyanin pigment content in the leaves. A distinct allocation of metabolic flow for B-ring trihydroxylated anthocyanins and catechins in 'Ziyan' was observed. Delphinidin, cyanidin, and pelargonidin (88.15 mg/100 g FW in total) but no other anthocyanin pigments were detected in 'Ziyan', and delphinidin (70.76 mg/100 g FW) was particularly predominant. An analysis of the catechin content in 'Ziyan' and eight other cultivars indicated that 'Ziyan' exhibits a preference for synthesizing B-ring trihydroxylated catechins (with a proportion of 74%). The full-length cDNA sequences of flavonoid pathway genes were isolated by RNA-Seq coupled with conventional TA cloning, and their expression patterns were characterized. Purple-leaved cultivars had lower amounts of total catechins, polyphenols, and water extract than ordinary non-anthocyanin cultivars but similar levels of caffeine. Because dark-purple-leaved Camellia species are rare in nature, this study provides new insights into the interplay between the accumulations of anthocyanins and other bioactive components in tea leaves.