Background Brassinosteroids (BRs) are a type of sterol plant hormone that play an important role in various biochemical and physiological reactions such as promoting cell growth, increasing biomass, and improving stress resistance. Results To investigate the regulatory and molecular mechanism of BRs on the growth and development of tea plants ( Camellia sinensis L.), changes in cell structure and gene expression levels of tea leaves treated with exogenous BRs were analyzed by electron microscopy and high-throughput Illumina RNA-Seq technology. The results showed that the number of starch granules in the chloroplasts and lipid globules increased and thylakoids expanded after BR treatment compared with the control. Transcriptome analysis showed that in the four BR treatments (CAA: BR treatment for 3 h, CAB: BR treatment for 9 h, CAC: BR treatment for 24 h, and CAD: BR treatment for 48 h), 3861 (1867 upregulated and 1994 downregulated), 5030 (2461 upregulated and 2569 downregulated), 1626 (815 upregulated and 811 downregulated), and 2050 (1004 upregulated and 1046 downregulated) differentially expressed genes were detected, respectively, compared with CAK (BR treatment for 0 h). Using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases, metabolic pathway enrichment analysis showed that the differentially expressed genes of CAA vs. CAK, CAB vs. CAK, CAC vs. CAK, and CAD vs. CAK significantly enriched the functional categories of signal transduction, cell cycle regulation, and starch, sucrose, and flavonoid biosynthesis and metabolism pathways. We also found that after spraying BR, the key genes for caffeine synthesis were downregulated. The results of qRT-PCR coincided with the findings of transcriptomic analysis. Conclusions The present study improved our understanding of the effects of BRs on the growth and development of tea leaves and laid the foundation for the in-depth analysis of signal transduction pathways of BRs in tea leaves.

MYB转录因子广泛参与植物的生长发育、生物以及非生物胁迫的应答过程，为探究茶树Cs MYB81的生物学功能，分析其表达模式。本研究以茶树（Camellia sinensis）品种‘碧香早’为材料，克隆和分析了CsMYB81的cDNA全长序列，对其序列和其编码的氨基酸序列进行了生物信息学分析，利用实时荧光定量PCR检测喷施赤霉素后不同部位的该基因表达水平。结果表明，Cs MYB81全长为1 676 bp，开放阅读框（ORF）全长1 632 bp，编码543个氨基酸，蛋白分子量为59.905 5 kD，等电点为4.99；具有高度保守的R2R3结构域和GAMYB特异性基序（BOX1, BOX2），二级结构预测结果表明CsMYB81蛋白含有螺旋-转角-螺旋（HTH）结构，符合MYB基因家族的结构特征。实时荧光定量PCR分析结果表明Cs MYB81在叶片和茶籽中表达较高，在茎、花和花粉中的表达量较低。对茶树喷施赤霉素（GA3），结果发现当用浓度为10 mmol/L的GA3处理叶片0.5 h时，CsMYB81呈显著表达趋势，推测CsMYB81参与茶树响应赤霉素的过程。本研究为探究茶树CsMYB81的生物学功能提供一定的科学依据，并且茶树CsMYB81在种子中高表达提示该基因可能参与了种子的萌发过程。

Tea (Camellia sinensis L.), an important economic crop, is recalcitrant to Agrobacterium-mediated transformation (AMT), which has seriously hindered the progress of molecular research on this species. The mechanisms leading to low efficiency of AMT in tea plants, related to the morphology, growth, and gene expression of Agrobacterium tumefaciens during tea-leaf explant infection, were compared to AMT of Nicotiana benthamiana leaves in the present work. Scanning electron microscopy (SEM) images showed that tea leaves induced significant morphological aberrations on bacterial cells and affected pathogen–plant attachment, the initial step of a successful AMT. RNA sequencing and transcriptomic analysis on Agrobacterium at 0, 3 and 4 days after leaf post-inoculation resulted in 762, 1923 and 1656 differentially expressed genes (DEGs) between the tea group and the tobacco group, respectively. The expressions of genes involved in bacterial fundamental metabolic processes, ATP-binding cassette (ABC) transporters, two-component systems (TCSs), secretion systems, and quorum sensing (QS) systems were severely affected in response to the tea-leaf phylloplane. Collectively, these results suggest that compounds in tea leaves, especially gamma-aminobutyrate (GABA) and catechins, interfered with plant–pathogen attachment, essential minerals (iron and potassium) acquisition, and quorum quenching (QQ) induction, which may have been major contributing factors to hinder AMT efficiency of the tea plant.

在单因素试验考察各原料添加比例对茶饮料感官得分的影响基础上,利用Design Expert(V.10.0.4)软件最优混料设计方法,采用模糊数学法对复合茯砖茶茶饮料的色泽、香气和口感进行感官评分,优化复合茶饮料的配方.结果表明,利用软件的优化功能和验证试验得出最佳配方为:茯砖茶40.2％、龙眼干36.2％、灵芝粉15.6％、茯苓粉8％,感官评分可以达到9.21,香味协调,口感细腻,甜度适中,无苦涩感;利用固相微萃取法GC-MS分析茶饮料中的挥发性成分有47种,主要由烯烃类、烷烃类、酚类、醛类、酯类、酮类、醇类化合物组成,呈现出茶饮料浓郁的"菌花香"并伴有花果香和甜香.本试验说明通过模糊数学结合D-最优混料设计法得到的茶饮料最佳配方稳定可靠,可为开发其他茶饮料或新型食品提供理论依据.

Tea is the most consumed beverage worldwide, and l-theanine in tea leaves significantly affects their flavor and market quality. We have developed and validated a fast and reliable gas chromatographic method with flame ionization detection (GC-FID) to quantify l-theanine after its extraction from Camellia sinensis (tea plant) and derivatization. The procedure was completed in 40 min, from extraction to chromatographic analysis, with a recovery rate of more than 93% and allowing a high sample throughput. The GC-FID intraday precision was within 0.57-2.28%, while the interday precision ranged from 1.57 to 13.48%. The intraday accuracy ranged from -6.84 to 5.26%, while the interday accuracy ranged from -1.08 to 3.12%. The limit of detection was 2.28 μg/mL, and the limit of quantification was 6.47 μg/mL. The GC-FID method was validated by high-performance liquid chromatography with UV detection (HPLC-UV) and was used to investigate the biosynthesis and regulation of l-theanine in tea plants. We found that plants fed with ethylamine significantly increased l-theanine concentrations in roots, while exogenous supplementation of glutamic acid, carbamide, and glutamine did not significantly affect the l-theanine level in roots. Our results also indicated that roots were not indispensable for the biosynthesis of l-theanine, which was detected in undifferentiated embryonic calluses in concentrations (g/100 g dry weight) as high as in leaves of whole plants (1.67 and 1.57%, respectively) and without any exogenous theanine precursor supplementation.