Xiaofang Zhu

Cuticle is the major transpiration barrier that restricts non-stomatal water loss and is closely associated with plant drought tolerance. Although multiple efforts have been made, it remains controversial what factors shape up the cuticular transpiration barrier. Previously, we found that the cuticle from the tender tea leaf was mainly constituted by very-long-chain-fatty-acids and their derivatives while alicyclic compounds dominate the mature tea leaf cuticle. The presence of two contrasting cuticle within same branch offered a unique system to investigate this question. In this study, tea seedlings were subjected to water deprivation treatment, cuticle structures and wax compositions from the tender leaf and the mature leaf were extensively measured and compared. We found that cuticle wax coverage, thickness, and osmiophilicity were commonly increased from both leaves. New waxes species were specifically induced by drought; the composition of existing waxes was remodeled; the chain length distributions of alkanes, esters, glycols, and terpenoids were altered in complex manners. Drought treatment significantly reduced leaf water loss rates. Wax biosynthesis-related gene expression analysis revealed dynamic expression patterns dependent on leaf maturity and the severity of drought. These data suggested that drought stress-induced structural and compositional cuticular modifications improve cuticle water barrier property. In addition, we demonstrated that cuticle from the tender leaf and the mature leaf were modified through both common and distinct modes.

Abstract The goal of the present study was to compare the structural and compositional differences of cuticle between tender leaf and fully-expanded leaf in Camellia sinensis , and provide metabolic base for the further characterization of wax biosynthesis in this economically important crop species. The tender second leaf and the fully-expanded fifth leaf from new twig were demonstrated to represent two different developmental stages, their cuticle thickness were measured by transmission electron microscopy. The thickness of the adaxial cuticle on the second and fifth leaf was 1.15 µm and 2.48 µm, respectively; the thickness of the abaxial cuticle on the second and fifth leaf was 0.47 µm and 1.05 µm, respectively. The thickness of the epicuticular wax layer from different leaf position or different sides of same leaf were similar. However, the intracuticular wax layer of the fifth leaf was much thicker than that of the second leaf. Total wax lipids were isolated from the second leaf and the fifth leaf, respectively. Gas chromatography-mass spectrometry analysis identified 51 wax constituents belonging to 13 chemical classes, including esters, glycols, terpenoids, fatty acids and their derivatives. Wax coverage on the second and fifth leaf was 4.76 µg/cm 2 and 15.38 µg/cm 2 , respectively. Primary alcohols dominated in the tender second leaf. However, triterpenoids were the major components from the fully-expanded fifth leaf. The predominant carbon chains varied depending on chemical class. These data showed that the wax profiles of Camellia sinensis leaves are development stage dependent, suggesting distinct developmental dependent metabolic pathways and regulatory mechanisms.

Camellia seed oil is a top-end quality of cooking oil in China. The oil quality and quantity are formed during seed maturation and desiccation. So far, it remains largely unresolved whether lipid degradation occurs and contributes to Camellia oil traits. In this study, three different Camellia germplasms, C. oleifera cv. Min 43 (M43), C. meiocarpa var. Qingguo (QG), and C. meiocarpa cv Hongguo (HG) were selected, their seed oil contents and compositions were quantified across different stages of seed desiccation. We found that at the late stage of desiccation, M43 and QG lost a significant portion of seed oil, while such an event was not observed in HG. To explore the molecular bases for the oil loss In M43, the transcriptomic profiling of M43 and HG was performed at the early and the late seed desiccation, respectively, and differentially expressed genes (DEGs) from the lipid metabolic pathway were identified and analyzed. Our data demonstrated that different Camellia species have diverse mechanisms to regulate seed oil accumulation and degradation, and that triacylglycerol-to-terpenoid conversion could account for the oil loss in M43 during late seed desiccation.

Introduction Primary Sjögren’s syndrome (pSS) is a common autoimmune disease, with the minor salivary gland (MSG) being the main affected tissue; however, its pathogenesis remains unclear. Although changes in long noncoding RNA (lncRNA) expression have been reported in pSS, their biological functions are uncertain, despite the regulatory roles suggested. Therefore, it would be meaningful to systematically investigate the gene expression of lncRNAs in pSS for their regulatory roles and possible contribution to the disease development. Methods Deep stranded total transcriptome sequencing was performed on MSG samples from 92 patients with pSS and 34 non-Sjögren’s syndrome (non-SS) controls. Differentially expressed genes between pSS and non-SS were identified, and a genome-wide competing endogenous RNA (ceRNA) network was constructed based on shared miRNA binding sites and gene–expression correlations. The regulatory roles of lncRNAs in dysregulated pathways in pSS were assessed by examining expression changes of interacting lncRNAs and coding genes. In vitro overexpression experiments in a salivary gland cell line were performed to evaluate the regulatory roles of three selected lncRNAs as ceRNAs. Results Genome-wide coding and noncoding gene expression correlation analysis suggests the regulatory function of lncRNAs in pSS. LncRNA could regulate coding gene expression via ceRNA mechanisms. The genome-wide ceRNA network comprising 3,035 lncRNAs and 10,838 coding genes was constructed. Eight lncRNAs were predicted to play essential roles on coding gene expression changes in pSS. The regulatory effect for three of the eight key lncRNAs—BISPR, LINC00926, and HCP5—were validated by in vitro experiment and their expression was correlated with clinical features of pSS. Discussion Systematic analysis of coding and lncRNA expression in MSG samples suggests a genome-wide regulatory role for lncRNAs in pSS. We constructed, for the first time, a genome-wide ceRNA network. This ceRNA network can be used to infer lncRNA functions based on their interacting coding genes. The gene regulatory roles of three lncRNAs were validated. Our study suggests that lncRNAs contribute significantly to coding gene expression changes in pSS via ceRNA mechanisms, and the identified regulatory lncRNA candidates could be useful for diagnosis, sub-classification, and treatment.