SMXL5 attenuates strigolactone signaling in Arabidopsis thaliana by inhibiting SMXL7 degradation.

Hormone-activated proteolysis is a recurring theme of plant hormone signaling mechanisms. In strigolactone signaling, the enzyme receptor DWARF14 (D14) and an F-box protein, MORE AXILLARY GROWTH2 (MAX2), mark SUPPRESSOR OF MAX2 1-LIKE (SMXL) family proteins SMXL6, SMXL7, and SMXL8 for rapid degradation. Removal of these transcriptional corepressors initiates downstream growth responses. The homologous proteins SMXL3, SMXL4, and SMXL5, however, are resistant to MAX2-mediated degradation. We discovered that the smxl4 smxl5 mutant has enhanced responses to strigolactone. SMXL5 attenuates strigolactone signaling by interfering with AtD14-SMXL7 interactions. SMXL5 interacts with AtD14 and SMXL7, providing two possible ways to inhibit SMXL7 degradation. SMXL5 function is partially dependent on an ethylene-responsive-element binding-factor-associated amphiphilic repression (EAR) motif, which typically mediates interactions with the TOPLESS family of transcriptional corepressors. However, we found that loss of the EAR motif reduces SMXL5-SMXL7 interactions and the attenuation of strigolactone signaling by SMXL5. We hypothesize that integration of SMXL5 into heteromeric SMXL complexes reduces the susceptibility of SMXL6/7/8 proteins to strigolactone-activated degradation and that the EAR motif promotes the formation or stability of these complexes. This mechanism may provide a way to spatially or temporally fine-tune strigolactone signaling through the regulation of SMXL5 expression or translation.

Assessment of the Genetic Relationship and Population Structure in Oil-Tea Camellia Species Using Simple Sequence Repeat (SSR) Markers.

Oil-tea camellia trees, the collective term for a class of economically valuable woody oil crops in China, have attracted extensive attention because of their rich nutritional and pharmaceutical value. This study aimed to analyze the genetic relationship and genetic diversity of oil-tea camellia species using polymorphic SSR markers. One-hundred and forty samples of five species were tested for genetic diversity using twenty-four SSR markers. In this study, a total of 385 alleles were identified using 24 SSR markers, and the average number of alleles per locus was 16.0417. The average Shannon's information index (I) was 0.1890, and the percentages of polymorphic loci (P) of oil-tea camellia trees were 7.79-79.48%, indicating that oil-tea camellia trees have low diversity. Analysis of molecular variance (AMOVA) showed that the majority of genetic variation (77%) was within populations, and a small fraction (23%) occurred among populations. Principal coordinate analysis (PCoA) results indicated that the first two principal axes explained 7.30% (PC1) and 6.68% (PC2) of the total variance, respectively. Both UPGMA and PCoA divided the 140 accessions into three groups. Camellia oleifera clustered into one class, Camellia vietnamensis and Camellia gauchowensis clustered into one class, and Camellia crapnelliana and Camellia chekiangoleosa clustered into another class. It could be speculated that the genetic relationship of C. vietnamensis and C. gauchowensis is quite close. SSR markers could reflect the genetic relationship among oil-tea camellia germplasm resources, and the results of this study could provide comprehensive information on the conservation, collection, and breeding of oil-tea camellia germplasms.

Comparison of the Main Metabolites in Different Maturation Stages of Camelliavietnamensis Huang Seeds.

Camellia vietnamensis Huang is an important woody oil crop in China, which has attracted much attention because of its abundant nutritional components and pharmaceutical value. Its seeds undergo a complex series of physiological and biochemical changes during maturation, with consequent alterations in metabolites. In order to investigate the endogenous metabolism of C. vietnamensis on Hainan Island during seed development, in this study, ultra-high-performance liquid tandem chromatography coupled with quadrupole time-of-flight mass spectrometry (UHPLC/Q-TOF-MS) and multivariate statistical analysis (MSA) were used to analyze the differences in the chemical compounds of C. vietnamensis seeds among the four maturation stages. A total of 293 metabolites were identified from the methanol extract of the seeds of C. vietnamensis. Five metabolites, belonging to benzene and substituted derivatives, 5'-deoxyribonucleosides and linear 1,3-diarylpropanoids, were found in all three comparison groups, with consistently down-regulated trends. The Kyoto Encyclopedia of Genes and Genomes (KEGG) results showed that phloretin and 5'-methylthioadenosine were the differentially expressed metabolites when seeds were in the growth periods of S2 and S3, and indole and L-tryptophan were the differentially expressed metabolites when seeds were in the growth periods of S3 and S4. In addition, 34 flavonoid metabolites were detected, of which 4 were differentially expressed. It was indicated that flavonoids dynamically change during all the oil-tea camellia seed development stages. The findings provide data for the better understanding of endogenous metabolic pathways during C. vietnamensis seed development.

Integrative Metabolome and Transcriptome Analysis Reveals the Regulatory Network of Flavonoid Biosynthesis in Response to MeJA in Camelliavietnamensis Huang.

Flavonoids are secondary metabolites widely found in plants, which perform various biological activities, such as antiinflammation, antioxidation, antitumor, and so on. Camellia vietnamensis Huang, a species of oil-tea Camellia tree, is an important woody oil crop species widely planted on Hainan Island, which provides health benefits with its high antioxidant activity and abundant flavonoid content. However, very little is known about the overall molecular mechanism of flavonoid biosynthesis in C. vietnamensis Huang. In this study, methyl jasmonate (MeJA) is used as an inducer to change the content of secondary metabolites in C. vietnamensis. Then, the potential mechanisms of flavonoid biosynthesis in C. vietnamensis leaves in response to MeJA were analyzed by metabolomics and transcriptomics (RNA sequencing). The results showed that metabolome analysis detected 104 flavonoids and 74 fatty acyls which showed different expression patterns (increased or decreased expression). It was discovered by KEGG analysis that three differentially accumulated metabolites (cinnamaldehyde, kaempferol and quercitrin) were annotated in the phenylpropanoid biosynthesis (ko00940), flavonoid biosynthesis (ko00941), and flavone and flavonol biosynthesis (ko00944) pathways. In the transcriptome analysis, 35 different genes involved in the synthesis of flavonoids were identified by MapMan analysis. The key genes (PAL, 4CL, CCR, CHI, CHS, C4H, FLS) that might be involved in the formation of flavonoid were highly expressed after 2 h of MeJA treatment. This study provides new insights and data supporting the molecular mechanism underlying the metabolism and synthesis of flavonoids in C. vietnamensis under MeJA treatment.

Quality Evaluation of the Oil of Camellia spp.

The oil of Camellia spp. has become a well-known high-quality edible oil because of its rich nutrition. It is of great significance to breed fine varieties of Camellia spp. for the sustainable growth of the Camellia spp. industry. This study mainly evaluated the quality and antioxidant capacity of the camellia seed from several sources. The fatty acid composition and main active components of 40 kinds of C. oleifera, C. vietnamensis, C. osmantha, and C. gigantocarpa seeds, and so on, from different regions, were tested using GC-MS and HPLC. The quality of different Camellia spp. germplasm resources was comprehensively evaluated using multiple indices. The unsaturated fatty acid content and the antioxidant capacity of C. vietnamensis from Hainan were higher than those of C. oleifera Abel. In addition, there were a few differences in the fatty acid compositions of Camellia spp. oil from different species. Correlation analysis confirmed that rutin, total saponin, total flavonoids, squalene, and vitamin E were strongly correlated to the antioxidant capacity of Camellia spp. In the comprehensive evaluation, the best quality and strongest antioxidant activity were found for Chengmai Dafeng (C. vietnamensis). These methods in the study were applied for the first time for the quality evaluation of the Camellia spp. species. This study provided new insights into the quality evaluation of the Camellia spp. species, thus facilitating further development of variety breeding along with quality evaluation.

cDNA cloning, prokaryotic expression, and functional analysis of squalene synthase (SQS) in Camellia vietnamensis Huang.

Camellia vietnamensis Huang, which belongs to Camellia oleifera, is a traditional Chinese medicinal plant widely planted on Hainan Island. Tea saponin is an important functional component of C. vietnamensis, and squalene is the precursor substance that controls its formation. Squalene synthase (SQS: EC 2.5.1.21) synthesizes squalene from 2 molecules of farnesyl pyrophosphate (FPP). In this study, 1683 bp of the C. vietnamensis SQS gene, designated as CvSQS, was cloned and encoded 414 amino acids. Bioinformatics and phylogenetic tree analysis revealed the high homology of CvSQS with squalene synthases from other plants. For soluble proteins, the carboxy-terminal deleted CvSQS was obtained for expression in Escherichia coli Transetta (DE3), and the recombinant protein with a weight of 42.5 kDa was detected using SDS-PAGE and Western blot. After an enzymatic reaction, the presence of squalene in the product was analyzed using GC-MS detection, which indicated that CvSQS had catalytic activity. The tissue specificity of CvSQS and its presence in seeds at various ripening stages was detected by q-RT PCR. CvSQS had the highest transcriptional level in leaves, followed by seeds, roots, and flowers; the amount of CvSQS in the seeds was highest in September. The identification and functional characterization of CvSQS is essential for further studies on the regulation mechanism of tea saponin in C. vietnamensis.

A cross-cultural test of the trauma model of dissociation.

In order to test the trauma model of dissociation, the authors compared two samples with similar rates of reported childhood physical and sexual abuse: 502 members of the general population in Winnipeg, Canada, and 304 psychiatric outpatients at Shanghai Mental Health Center in Shanghai, China. There is virtually no popular or professional knowledge of dissociative identity disorder in China, and therefore professional and popular contamination cannot be operating. According to the trauma model, samples from different cultures with similar levels of trauma should report similar levels of dissociation. According to the sociocognitive model, in contrast, pathological dissociation is not related to trauma and should be absent in samples free of cultural and professional contamination. Of the 304 Chinese respondents, 14.5% reported childhood physical and/or sexual abuse compared to 12.5% of the Canadian sample. Both samples reported similar levels of dissociation on the Dissociative Experiences Scale and the Dissociative Disorders Interview Schedule. The findings support a specific prediction of the trauma model of dissociation not tested in previous research, and are not consistent with the sociocognitive, contamination or iatrogenic models of dissociative identity disorder.

Trauma and dissociation in China.

OBJECTIVE: In order to determine whether pathological dissociation occurs in China, the authors conducted a survey among psychiatric inpatients, outpatients, and the general population in Shanghai, China. There is virtually no popular or professional knowledge of dissociative identity disorder in China, and therefore professional and popular contamination cannot exist. METHOD: Chinese versions of the Dissociative Experiences Scale and the Dissociative Disorders Interview Schedule were administered to 423 inpatients, 304 outpatients, and 618 factory workers in Shanghai by Chinese psychiatrists working at the Shanghai Mental Health Center. RESULTS: Dissociative disorders were diagnosed in 24 respondents by structured interview, and 15 respondents fell into the dissociative taxon on the Dissociative Experiences Scale. The outpatients reported the highest rates of childhood physical and/or sexual abuse and of pathological dissociation. CONCLUSIONS: Pathological dissociation can be detected readily among psychiatric outpatients in China but is much less common in the general population. Pathological dissociation is more frequent in more traumatized subsamples of the Chinese population. The findings are not consistent with the sociocognitive, contamination, or iatrogenic models of dissociative identity disorder.

Childhood physical and sexual abuse in China.

In order to determine the prevalence and characteristics of childhood physical and sexual abuse in China, the authors conducted a survey in Shanghai. The Dissociative Disorders Interview Schedule was administered to 423 inpatients and 304 outpatients at Shanghai Mental Health Center, and to a non-clinical sample of 618 workers at a clothing factory. The results were compared to a previous sample of 502 respondents in the general population in Winnipeg, Canada. The identities of the perpetrators of physical and sexual abuse, and the types of sexual abuse reported were similar in the two countries; however, the rates of reported abuse were lower in China. Childhood sexual abuse appears to be far less common in the general population in Canada than in China.