Isolation and Characterization of CsWRKY7, a Subgroup IId WRKY Transcription Factor from Camellia sinensis, Linked to Development in Arabidopsis.

WRKY transcription factors (TFs) containing one or two WRKY domains are a class of plant TFs that respond to diverse abiotic stresses and are associated with developmental processes. However, little has been known about the function of WRKY gene in tea plant. In this study, a subgroup IId WRKY gene CsWRKY7 was isolated from Camellia sinensis, which displayed amino acid sequence homology with Arabidopsis AtWRKY7 and AtWRKY15. Subcellular localization prediction indicated that CsWRKY7 localized to nucleus. Cis-acting elements detected in the promotor region of CsWRKY7 are mainly involved in plant response to environmental stress and growth. Consistently, expression analysis showed that CsWRKY7 transcripts responded to NaCl, mannitol, PEG, and diverse hormones treatments. Additionally, CsWRKY7 exhibited a higher accumulation both in old leaves and roots compared to bud. Seed germination and root growth assay indicated that overexpressed CsWRKY7 in transgenic Arabidopsis was not sensitive to NaCl, mannitol, PEG, and low concentration of ABA treatments. CsWRKY7 overexpressing Arabidopsis showed a late-flowering phenotype under normal conditions compared to wild type. Furthermore, gene expression analysis showed that the transcription levels of the flowering time integrator gene FLOWERING LOCUS T (FT) and the floral meristem identity genes APETALA1 (AP1) and LEAFY (LFY) were lower in WRKY7-OE than in the WT. Taken together, these findings indicate that CsWRKY7 TF may participate in plant growth. This study provides a potential strategy to breed late-blooming tea cultivar.

Bioinspired Hydrogel-Polymer Hybrids with a Tough and Antifatigue Interface via One-Step Polymerization.

Hydrogel hybrids are one of the key factors in life activities and biomimetic science; however, their development and utilization are critically impeded by their inadequate adhesive strength and intricate process. In nature, barnacles can stick to a variety of solid surfaces firmly (adhesive strength above 300 kPa) using a hydrophobic interface, which inspires us to firmly combine hydrogels and polymers through introducing an adhesive layer. By spreading a hydrophobic liquid membrane directly, tough combination of a hydrogel and a polymer substrate could be achieved after one-step polymerization. The fracture energy of the hydrogel attached to the surface of polyvinyl chloride was up to 1200 J m-2 and the tensile strength reached 1.21 MPa. Furthermore, the adhesion samples with this method exhibit an antifatigue performance, having withstood large bends and twists. It should be pointed out that this approach can also be applied to a variety of complicated surfaces. This work may expand the application range of hydrogels and provides an inspiration for hydrogel adhesion.

The complete chloroplast genome sequence of Camellia tachangensis F. C. Zhang (Theaceae).

To understand genetic background and phylogenetic position of Camellia tachangensis, we determined its complete chloroplast genome sequence which is 157,026 bp in length with overall GC content of 36.7%. It has four sub regions: a large single-copy (LSC) region (86,669 bp) and a small single-copy (SSC) region (18,253 bp) are separated by two inverted repeat (IR) regions (26,052 bp each). A total of 129 genes were annotated, containing 86 protein-coding genes, 35 tRNA genes, and 8 rRNA genes. Phylogenetic trees showed C. tachangensis clustered with Camellia gymnogyna and Camellia taliensis and separated from Camellia sinensis and its two varieties, Camellia sinensis var. assamica and Camellia sinensis var. pubilimba.

The complete chloroplast genome of an albino tea, Camellia sinensis cultivar 'Baiye 1'.

For obtaining the sequence and phylogenetic position of Camellia sinensis cultivar 'Baiye1', the complete chloroplast genome was determined. This chloroplast genome is 156,691 bp in length with overall GC content of 37.3%. It was comprised of a large single-copy (LSC) region of 86,585bp, a small single-copy (SSC) region of 18,276bp, and two inverted repeat (IR) regions of 26,083 bp. It contains 87 protein-coding, 8 rRNA, and 35 tRNA genes. Phylogenetic analysis showed 'Baiye1' and C. sinensis cv. 'Longjing43' were clustered into a group. These results may contribute to the further understanding of the albino phenotype and genetic evolution.

Transcriptome and metabolome analysis reveal candidate genes and biochemicals involved in tea geometrid defense in Camellia sinensis.

Tea plant (Camellia sinensis (L) O. Kuntze) respond to herbivore attack through large changes in defense related metabolism and gene expression. Ectropis oblique (Prout) is one of the most devastating insects that feed on tea leaves and tender buds, which can cause severe production loss and deteriorate the quality of tea. To elucidate the biochemicals and molecular mechanism of defense against tea geometrid (TG), transcriptome and metabolome of TG interaction with susceptible (SG) and resistance (RG) tea genotypes were analyzed by using UPLC-Q-TOF-MS, GC-MS, and RNA-seq technologies. This revealed that jasmonic acid was highly induced in RG, following a plethora of secondary metabolites involved in defense against TG could be induced by jasmonic acid signaling pathway. However, the constitutively present of salicylic acid in SG might be a suppressor of jasmonate signaling and thus misdirect tea plants against TG. Furthermore, flavonoids and terpenoids biosynthesis pathways were highly activated in RG to constitute the chemical barrier on TG feeding behavior. In contrast, fructose and theanine, which can act as feeding stimulants were observed to highly accumulate in SG. Being present in the major hub, 39 transcription factors or protein kinases among putative candidates were identified as master regulators from protein-protein interaction network analysis. Together, the current study provides a comprehensive gene expression and metabolite profiles, which can shed new insights into the molecular mechanism of tea defense against TG. The candidate genes and specific metabolites identified in the present study can serve as a valuable resource for unraveling the possible defense mechanism of plants against various biotic stresses.

Hydrogel with Ultrafast Self-Healing Property Both in Air and Underwater.

Self-healing hydrogels have a great potential application in 3D printing, soft robotics, and tissue engineering. There have been a large number of successful strategies for developing hydrogels that exhibit rapid and autonomous recovery. However, developing a gel with an excellent self-healing performance within several seconds is still an enormous challenge. Here, an ultrafast self-healing hydrogel based on an agarose/PVA double network (DN) is presented. The gel utilizing a dynamic borate bond exhibits 100% cure in strength and elongation after healing for 10 s in air, and this hydrogel shows an excellent self-healing property underwater as well. In addition, the agarose/PVA DN hydrogel exhibits a smart self-healing property for an in situ priority recovery, ensuring that the shape and the function are the same as those of the original one. With the combination of self-healing properties, such a hydrogel could be applied to a board range of areas.

A Novel F3' 5' H Allele with 14 bp Deletion Is Associated with High Catechin Index Trait of Wild Tea Plants and Has Potential Use in Enhancing Tea Quality.

Catechins are important chemical components determining the quality of tea. The catechin index (CI, ratio of dihydroxylated catechin (DIC)/trihydroxylated catechin (TRIC)) in the green leaf has a major influence on the amounts of theaflavins in black tea. In this work, the major catechin profiles of wild tea plants originating from Guizhou Province with high CI trait were investigated. We identified a novel flavonoid 3',5' hydroxylase gene ( F3' 5' H) allele with a 14 bp deletion in the upstream regulation region and developed an insertion/deletion (InDel) marker accordingly. The 14 bp deletion in the novel  F3' 5' H allele was associated with low F3' 5' H mRNA expression, thereby resulting in low TRIC content and high CI value. The allelic variant in the novel F3' 5' H allele associated with high CI values and DIC contents was confirmed by the introgression lines derived from a distant cross population. The novel F3' 5' H allele in wild tea plants is a valuable gene resource, which could be applied to breeding improvement on tea quality.

Quantitative Trait Loci Mapping for Theobromine and Caffeine Contents in Tea Plant ( Camellia sinensis).

Understanding the genetic basis of theobromine and caffeine accumulation in the tea plant is important due to their contribution to tea flavor. Quantitative trait loci (QTL) analyses were carried out to identify genetic variants associated with theobromine and caffeine contents and ratio using a pseudo-testcross population derived from an intervarietal cross between two varieties of Camellia sinensis. A total of 10 QTL controlling caffeine content (CAF), theobromine content (TBR), sum of caffeine and theobromine (SCT), and caffeine-to-theobromine ratio (CTR) were identified over four measurement years. The major QTL controlling CAF, qCAF1, was mapped onto LG01 and validated across years, explaining an average of 20.1% of the phenotypic variance. The other QTL were detected in 1 or 2 years, and of them there were four, two, and three for TBR, SCT, and CTR, respectively. The present results provide valuable information for further fine mapping and cloning functional genes and for genetic improvement in tea plant.

Identification and expression profiling of the auxin response factors (ARFs) in the tea plant (Camellia sinensis (L.) O. Kuntze) under various abiotic stresses.

Auxin response factor (ARF) proteins are a multigene family of regulators involved in various physiological and developmental processes in plants. However, their modes of action in the tea plant (Camellia sinensis) remain largely unknown. In this study, we identified 15 members of the tea ARF gene family, using the public information about C. sinensis, both in our laboratory, as well as in other laboratories, and analyzed their phylogenetic relationships, conserved domains and the compositions of the amino acids in the middle region. A comprehensive expression analysis in different tissues and organs revealed that many ARF genes were expressed in a tissue-specific manner, suggesting they have different functions in the growth and development processes of the tea plant. The expression analysis under three forms of auxin (indole-3-acetic acid, 2,4-dichlorophenoxyacetic acid, naphthylacetic acid) treatment showed that the majority of the ARF genes were down-regulated in the shoots and up-regulated in the roots, suggesting opposite action mechanisms of the ARF genes in the shoots and roots. The expression levels of most ARF genes were changed under various phytohormone and abiotic stresses, indicating the ARF gene family plays important roles in various phytohormone and abiotic stress signals and may mediate the crosstalk between phytohormones and abiotic stresses. The current study provides basic information for the ARF genes of the tea plant and will pave the way for deciphering the precise role of ARFs in tea developmental processes and breeding stress-tolerant tea varieties.

Seed structure characteristics to form ultrahigh oil content in rapeseed.

BACKGROUND: Rapeseed (Brassica napus L.) is an important oil crop in the world, and increasing its oil content is a major breeding goal. The studies on seed structure and characteristics of different oil content rapeseed could help us to understand the biological mechanism of lipid accumulation, and be helpful for rapeseed breeding. METHODOLOGY/PRINCIPAL FINDINGS: Here we report on the seed ultrastructure of an ultrahigh oil content rapeseed line YN171, whose oil content is 64.8%, and compared with other high and low oil content rapeseed lines. The results indicated that the cytoplasms of cotyledon, radicle, and aleuronic cells were completely filled with oil and protein bodies, and YN171 had a high oil body organelle to cell area ratio for all cell types. In the cotyledon cells, oil body organelles comprised 81% of the total cell area in YN171, but only 53 to 58% in three high oil content lines and 33 to 38% in three low oil content lines. The high oil body organelle to cotyledon cell area ratio and the cotyledon ratio in seed were the main reasons for the ultrahigh oil content of YN171. The correlation analysis indicated that oil content is significantly negatively correlated with protein content, but is not correlated with fatty acid composition. CONCLUSIONS/SIGNIFICANCE: Our results indicate that the oil content of YN171 could be enhanced by increasing the oil body organelle to cell ratio for some cell types. The oil body organelle to seed ratio significantly highly positively correlates with oil content, and could be used to predict seed oil content. Based on the structural analysis of different oil content rapeseed lines, we estimate the maximum of rapeseed oil content could reach 75%. Our results will help us to screen and identify high oil content lines in rapeseed breeding.