Integrated transcriptomic and metabolomic analyses reveal the effects of callose deposition and multihormone signal transduction pathways on the tea plant-Colletotrichum camelliae interaction

Colletotrichum infects diverse hosts, including tea plants, and can lead to crop failure. Numerous studies have reported that biological processes are involved in the resistance of tea plants to Colletotrichum spp. However, the molecular and biochemical responses in the host during this interaction are unclear. Cuttings of the tea cultivar Longjing 43 (LJ43) were inoculated with a conidial suspension of Colletotrichum camelliae, and water-sprayed cuttings were used as controls. In total, 10,592 differentially expressed genes (DEGs) were identified from the transcriptomic data of the tea plants and were significantly enriched in callose deposition and the biosynthesis of various phytohormones. Subsequently, 3,555 mass spectra peaks were obtained by LC-MS detection in the negative ion mode, and 27, 18 and 81 differentially expressed metabolites (DEMs) were identified in the tea leaves at 12 hpi, 24 hpi and 72 hpi, respectively. The metabolomic analysis also revealed that the levels of the precursors and intermediate products of jasmonic acid (JA) and indole-3-acetate (IAA) biosynthesis were significantly increased during the interaction, especially when the symptoms became apparent. In conclusion, we suggest that callose deposition and various phytohormone signaling systems play important roles in the tea plant-C. camelliae interaction.

CsSWEET1a and CsSWEET17 Mediate Growth and Freezing Tolerance by Promoting Sugar Transport across the Plasma Membrane

Sugars Will Eventually be Exported Transporters (SWEETs) are important in plant biological processes. Expression levels of CsSWEET1a and CsSWEET17 are induced by cold acclimation (CA) and cold stress in Camellia sinensis. Here, we found that CsSWEET17 was alternatively spliced, and its exclusion (Ex) transcript was associated with the CA process. Both plasma membrane-localized CsSWEET1a and CsSWEET17 transport hexoses, but cytoplasm-localized CsSWEET17-Ex does not. These results indicate that alternative splicing may be involved in regulating the function of SWEET transporters in response to low temperature in plants. The extra C-terminal of CsSWEET17, which is not found in the tonoplast fructose transporter AtSWEET17, did not affect its plasma membrane localization but promoted its sugar transport activities. The overexpression (OE) of CsSWEET1a and CsSWEET17 genes resulted in an increased sugar uptake in Arabidopsis, affecting plant germination and growth. The leaf and seed sizes of the CsSWEET17-OE lines were significantly larger than those of the wild type. Moreover, the OE of CsSWEET1a and CsSWEET17 significantly reduced the relative electrolyte leakage levels under freezing stress. Compared with the wild type, the expression of AtCWINV genes was suppressed in both CsSWEET1a-OE and CsSWEET17-OE lines, indicating the alteration in sugar contents in the cell walls of the OE lines. Furthermore, the interaction between CsSWEET1a and CsSWEET17 was confirmed using yeast two-hybrid and bimolecular fluorescence complementation assays. We showed that CsSWEET1a and CsSWEET17 form homo-/heterodimers in the plasma membrane and mediate the partitioning of sugars between the cytoplasm and the apoplast, thereby regulating plant growth and freezing tolerance.

Mitochondrial ribosomal protein S9M is involved in male gametogenesis and seed development in Arabidopsis

Mitochondrial function is critical for cell vitality in all eukaryotes including plants. Although plant mitochondria contain many proteins, few have been studied in the context of plant development and physiology. We used knock-down mutant RPS9M to study its important role in male gametogenesis and seed development in Arabidopsis thaliana. Knock-down of RPS9M in the rps9m-3 mutant led to abnormal pollen development and impaired pollen tube growth. In addition, both embryo and endosperm development were affected. Phenotype analysis revealed that the rps9m-3 mutant contained a lower amount of endosperm and nuclear proteins, and both embryo cell division and embryo pattern were affected, resulting in an abnormal and defective embryo. Lowering the level of RPS9M in rps9m-3 affects mitochondrial ribosome biogenesis, energy metabolism and production of ROS. Our data revealed that RPS9M plays important roles in normal gametophyte development and seed formation, possibly by sustaining mitochondrial function.

Lifestyle Characteristics and Gene Expression Analysis of Colletotrichum camelliae Isolated from Tea Plant [Camellia sinensis (L.) O. Kuntze] Based on Transcriptome

Colletotrichum camelliae is one of the most serious pathogens causing anthracnose in tea plants, but the interactive relationship between C. camelliae and tea plants has not been fully elucidated. This study investigated the gene expression changes in five different growth stages of C. camelliae based on transcriptome analysis to explain the lifestyle characteristics during the infection. On the basis of gene ontology (GO) enrichment analyses of differentially expressed genes (DEGs) in comparisons of germ tube (GT)/conidium (Con), appressoria (App)/Con, and cellophane infectious hyphae (CIH)/Con groups, the cellular process in the biological process category and intracellular, intracellular part, cell, and cell part in the cellular component category were significantly enriched. Hydrolase activity, catalytic activity, and molecular_function in the molecular function category were particularly enriched in the infection leaves (IL)/Con group. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis indicated that the DEGs were enriched in the genetic information processing pathway (ribosome) at the GT stage and the metabolism pathway (metabolic pathways and biosynthesis of secondary metabolism) in the rest of the stages. Interestingly, the genes associated with melanin biosynthesis and carbohydrate-active enzymes (CAZys), which are vital for penetration and cell wall degradation, were significantly upregulated at the App, CIH and IL stages. Subcellular localization results further showed that the selected non-annotated secreted proteins based on transcriptome data were majorly located in the cytoplasm and nucleus, predicted as new candidate effectors. The results of this study may establish a foundation and provide innovative ideas for subsequent research on C. camelliae.

ABA-dependent bZIP transcription factor, CsbZIP18, from Camellia sinensis negatively regulates freezing tolerance in Arabidopsis

Overexpression of the tea plant gene CsbZIP18 in Arabidopsis impaired freezing tolerance, and CsbZIP18 is a negative regulator of ABA signaling and cold stress. Basic region/leucine zipper (bZIP) transcription factors play important roles in the abscisic acid (ABA) signaling pathway and abiotic stress response in plants. However, few bZIP transcription factors have been functionally characterized in tea plants (Camellia sinensis). In this study, a bZIP transcription factor, CsbZIP18, was found to be strongly induced by natural cold acclimation, and the expression level of CsbZIP18 was lower in cold-resistant cultivars than in cold-susceptible cultivars. Compared with wild-type (WT) plants, Arabidopsis plants constitutively overexpressing CsbZIP18 exhibited decreased sensitivity to ABA, increased levels of relative electrolyte leakage (REL) and reduced values of maximal quantum efficiency of photosystem II (F_v/F_m) under freezing conditions. The expression of ABA homeostasis- and signal transduction-related genes and abiotic stress-inducible genes, such as RD22, RD26 and RAB18, was suppressed in overexpression lines under freezing conditions. However, there was no significant change in the expression of genes involved in the C-repeat binding factor (CBF)-mediated ABA-independent pathway between WT and CsbZIP18 overexpression plants. These results indicate that CsbZIP18 is a negative regulator of freezing tolerance via an ABA-dependent pathway.

Identification of antimicrobial metabolites produced by a potential biocontrol Actinomycete strain A217

AIMS

To extract and identify the metabolites of strain A217 as well as its antifungal spectrum and control effect on various plant pathogens.

METHODS AND RESULTS

Strain A217 was identified as a Streptomyces sp. which was most similar to Streptomyces lienomycini. An antimicrobial spectrum test indicated that strain A217 inhibited several plant pathogenic fungi and strong antibacterial effect such as Phytophthora capsici, Botrytis cinerea, Sclerotinia sclerotiorum, Fusarium oxysporum, Pseudomonas syringae and Xanthomonas campestris. An in vivo tissue test demonstrated that the fermentation broth of strain A217 exerted therapeutic and protective effects of 49·47 and 61·60% respectively, on S. sclerotiorum. Additionally, the fermentation broth of A217 exerted control effects on walnut black spot disease in walnut leaves and branches amounting to 79·33 and 81·52% respectively. In a pot experiment, the fermentation broth exhibited a stronger protective and control effect (68·29%), as well as better bacteriostatic and disease control effects on Phytophthora blight of pepper, compared with Metalaxyl. Compounds possessing antifungal and antibacterial activities were obtained from the fermentation broth of strain A217, using column chromatography and HPLC. Chemical and structural analyses conducted using MS and nuclear magnetic resonance confirmed that these compounds were 1H-pyrrole-2-carboxylic acid and 1H-pyrrole-2-carboxamide. The EC₅₀ values of compound 1H-pyrrole-2-carboxylic acid1 for S. sclerotiorum and P. capsici were 20·13 and 50·36 μg ml^-1 respectively. Compound 1H-pyrrole-2-carboxamide2 showed significant antibacterial activity against different plant pathogenic bacteria. The MIC values of P. syringae, X. campestris and X. campestris pv. jugiandis were 7·5, 30 and 15·0 μg ml^-1 respectively.

CONCLUSIONS

Actinomyces A217 fermentation products have a broad spectrum of bacteriostasis, and have good bacteriostasis activity to many plant pathogenic fungi and bacteria.

SIGNIFICANCE AND IMPACT OF THE STUDY

The present study revealed a new antimicrobial producing strain of Streptomyces and its potential application as a biological control agent for plant diseases.

Genome-wide identification and expression analysis of flowering-related genes reveal putative floral induction and differentiation mechanisms in tea plant (Camellia sinensis)

The tea leaf is economically important, while reproductive growth reduce tea output. However, little is known about flowering mechanisms in tea plants. Here, we determined the approximate times of floral induction, floral transition and floral organ differentiation by morphological observation. We identified 401 and 356 flowering-related genes from the genomes of Camellia sinensis var. sinensis and Camellia sinensis var. assamica, respectively. Then, we compared the expression profiles of flowering-related genes in floriferous and oliganthous cultivars, the result showed that PRR7, GI, GID1B and GID1C expression is correlated with the floral induction; LFY, PNF and PNY expression was correlated with floral bud formation. Transcriptome analysis also showed that GI, PRR7 and GID1 were correlated with stress-induced flowering. Thus, we proposed putative mechanisms of flowering in tea plants. This study provides new insights into flowering and a theoretical basis for balancing vegetative and reproductive growth in tea plants and other economical plants.

Pale green mutant analyses reveal the importance of CsGLKs in chloroplast developmental regulation and their effects on flavonoid biosynthesis in tea plant

Tea cultivars with leaf color variation have attracted increasing attention in tea production and research due to their unusual appearances and appealing flavors. However, the molecular mechanism underlying this variation is little known due to the unavailability of genetic transformation and a highly complex genome. Here, a natural tea plant mutant producing pale green branches (pgb) was discovered and characterized. Ultrastructural and biochemical analyses showed that the leaves of the pgb mutant had defective chloroplast structure and significantly lower pigment content than the normal control. Comprehensive expression detection of chloroplast-development-related genes further indicated that a significant downregulation of CsGLKs in the pgb mutant likely caused the chloroplast defect. Transcriptome analyses and polyphenolic compound determination highlighted a tight correlation between photosynthesis and secondary metabolite biosynthesis in tea plant. These results provide useful information illuminating the mechanism of chloroplast development and leaf color variation in tea plant.

[Effect of resection of adenoids and/or tonsil on the immune indexes in children with obstructive sleep apnea hypopnea syndrome]

Objective: To study the effect on immune indexes in children with obstructive sleep apnea hypopnea syndrome (OSAHS) before and after resection of adenoid and/or tonsil. Methods: A total of 100 children with OSAHS due to adenoid hypertrophy were enrolled in Department of Otorhinolaryngology Head and Neck Surgery, the Second Hospital of Dalian Medical University from December 2016 to December 2018. Some cases were complicated with tonsil hypertrophy or chronic tonsillitis. 6 ml of fasting peripheral venous blood were collected from all subjects at the 1st day before surgery, 4th day, 1 month, 3 months and 6 months after surgery to detect lymphoid subsets percentage (CD3(+), CD4(+),CD8(+), CD4/CD8, CD19, NK) and level of immunoglobulin (IgG, IgA, IgM). Grouping: group A was a total of 51 cases with adenoid hypertrophy after Adenoid plasma ablation; group B was a total of 27 cases with adenoid hypertrophy and chronic tonsillitis after plasma ablation of adenoid and tonsil; and group C was a total of 22 cases hypertrophy of adenoid and tonsil after plasma ablation of adenoid and tonsil.In the baseline data, age, gender and other variables were analyzed by anova and chi-square test, repeated measurement anova was used for intra-group and inter-group comparison of observation indicators at different time points after operation, and independent sample t-test was used for comparison between the two groups at observation points 3 months after operation. Results: (1) In group A, the percentage of CD19 lymphocytes before surgery was higher than that at 4th day after surgery, and the difference was statistically significant (21.85±6.20 vs.19.18±5.91, P<0.05). The other immune indexes were not statistically different before and after surgery (P>0.05). (2) In group B, the percentage of CD19 lymphocytes, CD3(+)T lymphocytes, CD8(+)T lymphocytes and the level of IgG at 4th day after surgery were significantly different between those before surgery (all P<0.05). At the 1st month after surgery, the percentage of CD3(+)T lymphocytes, CD8(+)T lymphocytes, CD19 lymphocytes and the level of IgG were significantly different between those before surgery (all P<0.05). The other immune indexes were not statistically different before and after operation (P>0.05). (3) In group C, the percentage of CD19 lymphocytes and the CD3(+)T lymphocytes at 4th day after surgery were significantly different between those before surgery (all P<0.05).In the 1st month after surgery, the percentage of CD8(+)T lymphocytes and CD19 lymphocytes were significantly different between those before surgery (all P<0.05). The other immune indexes were not statistically different before and after operation (P>0.05). (4) Among three groups, the percentage of CD4(+)T lymphocytes, the levels of IgG and IgA before surgery between group A and Group B were statistically significant (all P<0.05). At 4th day after surgery, the percentage of CD4(+)T lymphocytes in group B and C were lower than those in group A, and the differences were statistically significant (32.22±6.14, 32.36±6.87 vs. 36.36±5.19, all P<0.05); the other immune indexes were not statistically different among each group before and after surgery (P>0.05). Conclusions: Resection of adenoid has no significant effect on the immune indexes in children with OSAHS. The children with OSAHS complicated with tonsil problems have immune index disorder before surgery. Surgery has a certain effect on the immune indexes of children with OSAHS in a short period of time, and tends to normal level after one month.

Diversity of Pestalotiopsis-Like Species Causing Gray Blight Disease of Tea Plants (Camellia sinensis) in China, Including two Novel Pestalotiopsis Species, and Analysis of Their Pathogenicity

Several Pestalotiopsis-like species cause gray blight disease in tea plants, resulting in severe tea production losses. However, systematic and comprehensive research on the diversity, geographical distribution, and pathogenicity of pathogenic species associated with tea plants in China is limited. In this study, 168 Pestalotiopsis-like isolates were obtained from diseased tea plant leaves from 13 primary tea-producing provinces and cities in China. Based on a multilocus (internal transcribed spacer, translation elongation factor 1-α, and β-tubulin gene region) phylogenetic analysis coupled with an assessment of conidial characteristics, 20 Neopestalotiopsis unclassified isolates, seven Pestalotiopsis species, including two novel (Pestalotiopsis menhaiensis and Pestalotiopsis sichuanensis), four known (Pestalotiopsis camelliae, Pestalotiopsis chamaeropis, Pestalotiopsis kenyana, and Pestalotiopsis rhodomyrtus) and one indistinguishable species, and three Pseudopestalotiopsis species, including two known (Pseudopestalotiopsis camelliae-sinensis and Pseudopestalotiopsis chinensis) and one indistinguishable species, were identified. This study is the first to evaluate Pestalotiopsis chamaeropis on tea plants in China. The geographical distribution and pathogenicity tests showed Pseudopestalotiopsis camelliae-sinensis to be the dominant cause of gray blight of tea plants in China. In vitro antifungal assays demonstrated that theobromine not only derepressed mycelial growth of the 29 representative isolates but also increased their growth. Correlation analysis revealed a linear positive relationship between the mycelial growth rate and pathogenicity (P = 0.0148).

The involvements of calcium-dependent protein kinases and catechins in tea plant [Camellia sinensis (L.) O. Kuntze] cold responses

Temperature is one of the most important environmental factors limiting tea plant growth and tea production. Previously we reported that both Ca²⁺ and ROS signals play important roles in tea plant cold acclimation. Here, we identified 26 CsCPK transcripts, analyzed their phylogenetic and sequence characters, and detected their transcriptions to monitor Ca²⁺ signaling status. Tissue-specific expression profiles indicated that most CsCPK genes were constitutively expressed in tested tissues, suggesting their possible roles in development. Cold along with calcium inhibitor assays suggested that CsCPKs are important cold regulators and CsCPK30/5/4/9 maybe the key members. Moreover, LaCl₃ or EGTA pre-treatment could result in impaired Ca²⁺ signaling and compromised cold-responding network, but higher catechins accumulation revealed their potential positive roles in cold responses. Those findings indicated that catechins and other secondary metabolites in tea plant may form an alternative cold-responding network that closely correlated with Ca²⁺ signaling status.

Fetal cardiac tumor: echocardiography, clinical outcome and genetic analysis in 53 cases

OBJECTIVE

To analyze the imaging and clinical features of fetal cardiac tumors, and to explore the relationship between tuberous sclerosis complex (TSC) and cardiac rhabdomyoma in the fetus.

METHODS

Fifty-three women pregnant with a fetus affected by cardiac tumor(s) were examined by standardized fetal echocardiography (FE), and fetuses, mothers and fathers, including other relevant family members if necessary, underwent familial TSC genetic testing. Relevant pathological features, including pathological findings at clinical examination of liveborn infants and autopsy findings in terminated cases, were noted.

RESULTS

Of the 53 fetuses, 37 had multiple cardiac tumors and 16 had a single cardiac tumor detected by FE. In all 53 fetuses and their families, TSC genetic testing was successful, showing that 37 of the fetuses had a TSC1 (n = 6) or TSC2 (n = 31) pathogenic or suspected pathogenic mutation, of which 25 were spontaneous and 12 were familial mutations. The proportion of single and multiple cardiac tumors at FE was significantly different between the group of fetuses with positive genetic test results and that with negative results for TSC (31% and 86%, respectively), although the presence of multiple or single tumors was not associated with the type of TSC mutation. The decision to terminate the pregnancy was made by 45 women and their families, and eight fetuses were liveborn. Autopsy was performed in 38 fetuses, which revealed 36 cases with pathologically confirmed cardiac rhabdomyoma, one case of hemangioma and one case of fibroma. 93% of fetuses with multiple rhabdomyomas at autopsy and 71% of those with a single cardiac rhabdomyoma harbored a TSC1 or TSC2 mutation.

CONCLUSION

Cardiac rhabdomyoma is the most common cardiac tumor in the fetus. The correlation between cardiac rhabdomyoma and TSC is strong regardless of the presence of single or multiple tumors. For fetuses with suspected cardiac rhabdomyoma identified by FE, prenatal genetic testing for TSC of both fetus and family members is recommended. A positive genetic diagnosis can help in counseling and planning for neonatal treatment. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Expression patterns of alpha-amylase and beta-amylase genes provide insights into the molecular mechanisms underlying the responses of tea plants (Camellia sinensis) to stress and postharvest processing treatments

The alpha-amylase and beta-amylase genes have been identified from tea plants, and their bioinformatic characteristics and expression patterns provide a foundation for further studies to elucidate their biological functions. Alpha-amylase (AMY)- and beta-amylase (BAM)-mediated starch degradation plays central roles in carbohydrate metabolism and participates extensively in the regulation of a wide range of biological processes, including growth, development and stress response. However, the AMY and BAM genes in tea plants (Camellia sinensis) are poorly understood, and the biological functions of these genes remain to be elucidated. In this study, three CsAMY and nine CsBAM genes from tea plants were identified based on genomic and transcriptomic database analyses, and the genes were subjected to comprehensive bioinformatic characterization. Phylogenetic analysis showed that the CsAMY proteins could be clustered into three different subfamilies, and nine CsBAM proteins could be classified into four groups. Putative catalytically active proteins were identified based on multiple sequence alignments, and the tertiary structures of these proteins were analyzed. Cis-element analysis indicated that CsAMY and CsBAM were extensively involved in tea plant growth, development and stress response. In addition, the CsAMY and CsBAM genes were differentially expressed in various tissues and were regulated by stress treatments (e.g., ABA, cold, drought and salt stress), and the expression patterns of these genes were associated with the postharvest withering and rotation processes. Taken together, our results will enhance the understanding of the roles of the CsAMY and CsBAM gene families in the growth, development and stress response of tea plants and of the potential functions of these genes in determining tea quality during the postharvest processing of tea leaves.

Experimental Observation of Single Skyrmion Signatures in a Magnetic Tunnel Junction

We have deterministically created a stable topological spin texture in magnetic tunnel junctions (MTJ) by using pulsed or microwave currents. The spin texture is characterized by a field-dependent intermediate resistance state and a new magnetic resonance. Micromagnetic simulations show that the observations are consistent with the nucleation of a single skyrmion, facilitated by a spatially nonuniform stray field. The unique resonance spectrum is identified as the skyrmion breathing mode and a skyrmion diameter of 75 nm is estimated. This work shows the possibility to create skyrmions in MTJs without the Dzyaloshinskii-Moriya interaction and could lead to noninvasive, on-chip skyrmion measurement.

Evaluation of Diffusional Kurtosis Imaging in Sub-acute Ischemic Stroke: Comparison with Rehabilitation Treatment Effect

Stroke is a serious worldwide medical condition that causes neurological function disability. Diffusional kurtosis imaging, which measures the non-Gaussianity of water diffusion, has been demonstrated to be a sensitive biomarker in many neuro-pathologies. This study explores the relationship between neural function recovery and transformation of the ischemic lesion and/or corticospinal tract during the sub-acute phase after stroke by using diffusional kurtosis imaging. We performed a prospective study of function recovery and K metrics of 43 patients with sub-acute ischemic stroke in the middle cerebral artery territory. The effect of rehabilitation treatment was evaluated using both the Fugl-Meyer motor function score and modified Barthel index score at post-treatment compared with admission, and patients were allocated to two groups: good and poor rehabilitation effect (GRE and PRE). Metrics of diffusional kurtosis imaging within ischemic lesion and along the corticospinal tract were acquired, respectively. All three relative axial diffusional kurtoses (rKas) along the corticospinal tract in the GRE group ( n = 21) were significantly larger than those of the PRE group ( n = 22), including rKa in the posterior limb of internal capsule, rKa in the cerebral peduncle, and rKa in the basal part of the pons ( p = 0.014, 0.005, and 0.021, respectively). This multi-parametric magnetic resonance imaging study showed that diffusional kurtosis imaging has the potential to complement existing stroke imaging techniques and revealed its own advantages in elucidating the possible biophysical mechanism of functional restoration underlying ischemic stroke.

Long non-coding RNA in osteogenesis: A new world to be explored

Long non-coding RNAs (lncRNAs) are transcripts longer than 200 nucleotides with limited coding potential, which have emerged as novel regulators in many biological and pathological processes, including growth, development, and oncogenesis. Accumulating evidence suggests that lncRNAs have a special role in the osteogenic differentiation of various types of cell, including stem cells from different sources such as embryo, bone marrow, adipose tissue and periodontal ligaments, and induced pluripotent stem cells. Involved in complex mechanisms, lncRNAs regulate osteogenic markers and key regulators and pathways in osteogenic differentiation. In this review, we provide insights into the functions and molecular mechanisms of lncRNAs in osteogenesis and highlight their emerging roles and clinical value in regenerative medicine and osteogenesis-related diseases.

Cite this article: J. Zhang, X. Hao, M. Yin, T. Xu, F. Guo. Long non-coding RNA in osteogenesis: A new world to be explored. Bone Joint Res 2019;8:73–80. DOI: 10.1302/2046-3758.82.BJR-2018-0074.R1.