Novel therapeutic targets, including IGFBP3, of umbilical cord mesenchymal stem-cell-conditioned medium in intrauterine adhesion.

Mesenchymal stem cells play important roles in repairing injured endometrium. However, the molecular targets and potential mechanism of the endometrial recipient cells for stem cell therapy in intrauterine adhesion (IUA) are poorly understood. In this study, umbilical cord mesenchymal stem-cell-conditioned medium (UCMSCs-CM) produced positive effects on a Transforming growth factor beta (TGF-ß) induced IUA cell model. RNA-sequencing was performed on clinical IUA tissues, and the top 40 upregulated and top 20 downregulated mRNAs were selected and verified using high-throughput (HT) qPCR in both tissues and cell models. Based on a bioinformatic analysis of RNA-sequencing and HT-qPCR results, 11 mRNAs were uncovered to be the intervention targets of UCMSCs-CM on IUA endometrium cell models. Among them, IGFBP3 was striking as a key pathogenic gene and a potential diagnostic marker of IUA, which exhibited the area under the curve (AUC), sensitivity, specificity were 0.924, 93.1% and 80.6%, respectively in 60 endometrial tissues. The silencing of IGFBP3 exerted positive effects on the IUA cell model through partially upregulating MMP1 and KLF2. In conclusion, RNA-sequencing combined with HT qPCR based on clinical tissues and IUA cell models were used in IUA research and our results may provide some scientific ideas for the diagnosis and treatment of IUA.

Effect of prior female SARS-CoV-2 infection on IVF outcomes: a prospective cohort study.

Introduction: The clinical impact of SARS-CoV-2 infection on human reproduction remains controversial. This prospective cohort study aimed to assess the effect of prior female SARS-CoV-2 infection on subsequent in vitro fertilization (IVF) outcomes. Materials and methods: A total of 451 women who underwent fresh IVF treatment between December 1, 2022 and April 30, 2023 were included from an academic fertility center. Participants were divided into the infected group if they had a prior COVID-19 history before cycle initiation (n = 252), while the control group were those uninfected (n = 199). The primary outcomes were the number of oocytes retrieved and clinical pregnancy rate after fresh embryo transfer. Multivariate linear and logistic regression analyses were conducted to control for potential confounders. Results: The number of oocytes retrieved (11.4 ± 8.3 vs. 11.6 ± 7.7; P = 0.457) and clinical pregnancy rate (70.3% vs. 73.7%; P = 0.590) were similar between infected and uninfected groups, with a fully adjusted ß coefficient of 0 (95% confidence interval [CI]: -0.14-0.13) and odds ratio of 0.64 (95% CI: 0.20-2.07), respectively. Consistently, the two groups were comparable in cycle characteristics as well as other laboratory and pregnancy parameters. In both subgroup analyses and restricted cubic splines, different post-infection time intervals to IVF cycle initiation showed no significant associations with treatment outcomes. Conclusion: Prior SARS-CoV-2 infection in females had no adverse influence on subsequent IVF treatment, regardless of the time interval following infection. Our findings provide reassurance for infected women planning for assisted reproduction. Additional prospective cohort studies with larger datasets and longer follow-up are required to confirm the conclusion.

Effects of biochar additions on the mechanical stability of soil aggregates and their role in the dynamic renewal of aggregates in slope ecological restoration.

Mechanical stability of soil aggregates is important for resisting external disturbances in slope soils. Biochar (BC) is widely used in slope remediation. However, biochar application may not be conducive to the formation of mechanical-stable soil aggregates, and the effects of biochar additions on the mechanical stability of soil aggregates in slope restoration remain largely unclear. In this context, an incubation experiment was conducted in this study with four biochar levels added to artificial soil, namely 0 % (BC0), 1.5 % (BC1), 3 % (BC2), and 4.5 % (BC3), corresponding approximately to 0, 0.77, 1.53 and 2.30 M ha-1, respectively. The contributions of different soil aggregate fractions to maintaining the mechanical stability of aggregates, as well as the main influencing factors and pathways of biochar additions on soil aggregate stability in a dynamic renewal process of aggregates, were investigated in this study. The results showed a decreasing trend in the mean weight diameter (MWD) with increasing biochar levels and BC1 has no significant difference with BC0, showing MWD values of 2.74 and 2.75, respectively. In contrast, BC3 is significantly lower MWD value of 2.18. The BC3 exhibited negative impact on the mechanical stability of the aggregates. Redundancy analysis (RDA) showed that large macroaggregates (>5 mm) exhibited a stronger contribution on the aggregate mechanical stability between all soil aggregate fractions. The random forest (RF) algorithm and structural equation modeling (SEM) indicated that microaggregate-associated soil organic carbon (SOC) contents and soil pH values were the main factors driving the changes in the aggregate mechanical stability caused by biochar applications. Indeed, the biochar level of 1.5 % maintained the stability of macroaggregates and increased the microaggregate-associated SOC content by 35.7 %, which was conducive to the formation of microaggregates within macroaggregates. Our study suggests that the application of biochar at a level of 1.5 % is more beneficial for maintaining the mechanical stability of artificial soil aggregates.

Effect of female coronavirus disease 2019 vaccination on assisted reproductive outcomes: a systematic review and meta-analysis.

IMPORTANCE: The effect of coronavirus disease 2019 (COVID-19) vaccination on fertility warrants clarification in women undergoing assisted reproductive treatment. OBJECTIVE: To study the association between female COVID-19 vaccination and outcomes of assisted reproductive treatment. DATA SOURCES: PubMed, Embase, the Web of Science, Cochrane Library, and medRxiv and bioRxiv were searched for eligible studies from December 1, 2019, to November 30, 2022, with no language restrictions. STUDY SELECTION AND SYNTHESIS: Observational studies comparing assisted reproductive outcomes between women with and without COVID-19 vaccination were included. The pooled estimates were calculated using the random-effects models as mean differences (MDs), standardized MDs, or odds ratios with 95% confidence intervals (CIs). Heterogeneity was evaluated using the I2 statistic. MAIN OUTCOMES: The number of oocytes retrieved and clinical pregnancy rate. RESULTS: Twenty-one cohort studies involving a total of 19,687 treatment cycles were included. In a comparison of the vaccinated vs. unvaccinated groups, the pooled MD for oocyte number was -0.06 (95% CI, -0.51 to 0.39; I2 = 0), and the pooled odds ratio for clinical pregnancy was 0.95 (95% CI, 0.85-1.05; I2 = 0). Similarly, there were no statistically significant adverse effects identified in other outcomes determined a priori, including 4 cycle characteristics, 6 laboratory parameters, and 3 pregnancy indicators. Most results were consistently unchanged in subgroup and sensitivity analyses, with no evidence of publication bias according to Egger's test. CONCLUSION AND RELEVANCE: Our work did not find significant differences in assisted reproductive outcomes between vaccinated and unvaccinated women. However, more data are warranted to confirm the safety of COVID-19 vaccination for assisted reproductive treatment and in female fertility in general.

A simulated ecological restoration of bare cut slope reveals the dosage and temporal effects of cement on ecosystem multifunctionality in a mountain ecosystem.

Cement is a critical building material used in the restorations of bare cut slopes. Yet, how cement affects ecosystem's functions and their undertakers remains elusive. Here, we revealed the dosage and temporal effects of cement on plant and soil traits, extracellular enzymes, greenhouse gas fluxes and microbiome using simulation experiments. The results showed that soil pH increased with the cement content at 1st day but relatively constant values around 7 to 7.5 were detected in the flowing days. The ß-1,4-glucosidase, phenol oxidase, leucine aminopeptidase and acid phosphatase showed high activities under high cement content, and they generally increased with the cultivations except for acid phosphatase. CH4 fluxes at 16th day were less than zero, and they increased to peak around at 37th to 44th days followed by decreasing until reaching to relatively stable fluctuations around 0. Despite of decrease patterns, N2O fluxes stayed around zero across the temporal gradient except for the maximum around at 30th day in 2%, 5% and 8% cement treatment. Microbial diversity decreased with the cement content, in which there were a recovery trend for bacteria. By integrating above- and belowground ecosystem traits into a multifunctionality index, we identified a potential optimum cement content (11%). PLSPM showed that multifunctionality was affected by the shifts in soil bacterial community, enzyme activity and greenhouse gases while these components were effected by other environmental changes resulted from cement. Our results demonstrate that cement determines multifunctionality through mediating microbial community and activity, providing new insights for designing in situ experiments and ecological restoration strategies for bare cut slopes.

Drought and low temperature-induced NF-YA1 activates FT expression to promote citrus flowering.

Flower induction in adult citrus is mainly regulated by drought and low temperatures. However, the mechanism of FLOWERING LOCUS T regulation of citrus flowering (CiFT) under two flower-inductive stimuli remains largely unclear. In this study, a citrus transcription factor, nuclear factor YA (CiNF-YA1), was found to specifically bind to the CiFT promoter by forming a complex with CiNF-YB2 and CiNF-YC2 to activate CiFT expression. CiNF-YA1 was induced in juvenile citrus by low temperature and drought treatments. Overexpression of CiNF-YA1 increased drought susceptibility in transgenic citrus, whereas suppression of CiNF-YA1 enhanced drought tolerance in silenced citrus plants. Furthermore, a GOLDEN2 - LIKE protein (CiFE) that interacts with CiFT protein was also isolated. Further experimental evidence showed that CiFE binds to the citrus LEAFY (CiLFY) promoter and activates its expression. In addition, the expressions of CiNF-YA1 and CiFE showed a seasonal increase during the floral induction period and were induced by artificial drought and low-temperature treatments at which floral induction occurred. These results indicate that CiNF-YA1 may activate CiFT expression in response to drought and low temperatures by binding to the CiFT promoter. CiFT then forms a complex with CiFE to activate CiLFY, thereby promoting the flowering of adult citrus.

Impact of inactivated SARS-CoV-2 vaccination on embryo ploidy: a retrospective cohort study of 133 PGT-A cycles in China.

BACKGROUND: Unsubstantiated concerns have been raised on the potential correlation between severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination and infertility, leading to vaccine hesitancy in reproductive-aged population. Herein, we aim to evaluate the impact of inactivated SARS-CoV-2 vaccination on embryo ploidy, which is a critical indicator for embryo quality and pregnancy chance. METHODS: This was a retrospective cohort study of 133 patients who underwent preimplantation genetic testing for aneuploidy (PGT-A) cycles with next-generation sequencing technology from June 1st 2021 to March 17th 2022 at a tertiary-care medical center in China. Women fully vaccinated with two doses of Sinopharm or Sinovac inactivated vaccines (n = 66) were compared with unvaccinated women (n = 67). The primary outcome was the euploidy rate per cycle. Multivariate linear and logistic regression analyses were performed to adjust for potential confounders. RESULTS: The euploidy rate was similar between vaccinated and unvaccinated groups (23.2 ± 24.6% vs. 22.6 ± 25.9%, P = 0.768), with an adjusted ß of 0.01 (95% confidence interval [CI]: -0.08-0.10). After frozen-thawed single euploid blastocyst transfer, the two groups were also comparable in clinical pregnancy rate (75.0% vs. 60.0%, P = 0.289), with an adjusted odds ratio of 6.21 (95% CI: 0.76-50.88). No significant associations were observed between vaccination and cycle characteristics or other laboratory and pregnancy outcomes. CONCLUSIONS: Inactivated SARS-CoV-2 vaccination had no detrimental impact on embryo ploidy during in vitro fertilization treatment. Our finding provides further reassurance for vaccinated women who are planning to conceive. Future prospective cohort studies with larger datasets and longer follow-up are needed to confirm the conclusion.

Functional analysis of a PISTILLATA-like gene CcMADS20 involved in floral organs specification in citrus.

PISTILLATA (PI), as a member of MADS-box transcription factor, plays an important role in petal and stamen specification in Arabidopsis. However, little is known about PI-like genes in citrus. To understand the molecular mechanism of PI during the developmental process of citrus flower, a PI-like gene CcMADS20 was isolated from Citrus Clemantina. Sequence alignment and phylogenetic analysis revealed that CcMADS20 had relatively high similarity with PI-like homolog and was classified in the core dicotyledonous group. The temporal and spatial expression analyses showed that CcMADS20 was specifically expressed in petal and stamen of citrus flower, which was consistent with PI expression pattern in Arabidopsis. Protein interaction revealed that CcMADS20 could form heterodimer with AP3-like proteins. Furthermore, ectopic overexpression of CcMADS20 in Arabidopsis resulted in transformation of sepals into petal-like structure, as observed in other plants overexpressing a functional PI-like homolog. Additionally, promoter fragments of CcMADS20 were also cloned in the representative 21 citrus varieties. Interestingly, four types of promoters were discovered in these citrus varieties, resulting from two stable insert/deletion fragments (Locus1 and Locus2). The homo/hetero-zygosity of promoter alleles in each variety was strongly related to the evolutionary origin of citrus. Four promoters activity analysis indicated that Locus1 presence inhibited CcMADS20 transcriptional activity and Locus2 presence promoted its transcriptional activity. These findings suggested that CcMADS20 determines petal and stamen development during the evolutionary process of citrus and four promoters discovered, as effective genetic markers, are valuable for citrus breeding practices.

No Effect of Inactivated SARS-CoV-2 Vaccination on in vitro Fertilization Outcomes: A Propensity Score-Matched Study.

PURPOSE: To investigate the impact of inactivated SARS-CoV-2 vaccination on in vitro fertilization (IVF) outcomes. PATIENTS AND METHODS: This retrospective cohort study included 2185 patients undergoing fresh IVF cycles from June 1st to September 13th 2021 in a single university-affiliated hospital. Vaccine administration information was collected and ascertained via immunization records. Patients with two dosages of inactivated SARS-CoV-2 vaccines (Sinopharm or Sinovac) were categorized into the vaccinated group (n = 150), while those unvaccinated were classified as control (n = 2035). Propensity score matching was performed to balance the baseline characteristics (14 covariates) between the two groups at a ratio of 1:4. The main outcome measures were the number of oocytes retrieved, good-quality embryo rate and clinical pregnancy rate. RESULTS: There were 146 women in the vaccinated group and 584 in the control group after matching. The number of oocytes retrieved (9.9 ± 7.1 vs 9.9 ± 6.7; P = 0.893), good-quality embryo rate (33.5 ± 29.8% vs 29.9 ± 28.6%; P = 0.184) and clinical pregnancy rate (59.1% vs 63.6%; P = 0.507) were all similar between the two groups. In addition, no significant differences were observed regarding other cycle characteristics, laboratory parameters and pregnancy outcomes. The results were also comparable when vaccinated patients were subdivided into three categories based on the time interval from complete vaccination to cycle initiation: ≤1 month, >1-2 months, and >2 months. CONCLUSION: Our study provided the first-time evidence that inactivated SARS-CoV-2 vaccination in females did not result in any measurable detrimental effects on IVF treatment. Owing to the present limitations, further prospective studies with larger cohort size and longer follow-up are warranted to validate our conclusion.

The impact of air pollution on COVID-19 pandemic varied within different cities in South America using different models.

There is a rising concern that air pollution plays an important role in the COVID-19 pandemic. However, the results were not consistent on the association between air pollution and the spread of COVID-19. In the study, air pollution data and the confirmed cases of COVID-19 were both gathered from five severe cities across three countries in South America. Daily real-time population regeneration (Rt) was calculated to assess the spread of COVID-19. Two frequently used models, generalized additive models (GAM) and multiple linear regression, were both used to explore the impact of environmental pollutants on the epidemic. Wide ranges of all six air pollutants were detected across the five cities. Spearman's correlation analysis confirmed the positive correlation within six pollutants. Rt value showed a gradual decline in all the five cities. Further analysis showed that the association between air pollution and COVID-19 varied across five cities. According to our research results, even for the same region, varied models gave inconsistent results. For example, in Sao Paulo, both models show SO2 and O3 are significant independent variables, however, the GAM model shows that PM10 has a nonlinear negative correlation with Rt, while PM10 has no significant correlation in the multiple linear model. Moreover, in the case of multiple regions, currently used models should be selected according to local conditions. Our results indicate that there is a significant relationship between air pollution and COVID-19 infection, which will help states, health practitioners, and policy makers in combating the COVID-19 pandemic in South America.

Impact of inactivated SARS-CoV-2 vaccination on embryo ploidy: a retrospective cohort study of 133 PGT-A cycles in China

BACKGROUND: Unsubstantiated concerns have been raised on the potential correlation between severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination and infertility, leading to vaccine hesitancy in reproductive-aged population. Herein, we aim to evaluate the impact of inactivated SARS-CoV-2 vaccination on embryo ploidy, which is a critical indicator for embryo quality and pregnancy chance. METHODS: This was a retrospective cohort study of 133 patients who underwent preimplantation genetic testing for aneuploidy (PGT-A) cycles with next-generation sequencing technology from June 1st 2021 to March 17th 2022 at a tertiary-care medical center in China. Women fully vaccinated with two doses of Sinopharm or Sinovac inactivated vaccines (n = 66) were compared with unvaccinated women (n = 67). The primary outcome was the euploidy rate per cycle. Multivariate linear and logistic regression analyses were performed to adjust for potential confounders. RESULTS: The euploidy rate was similar between vaccinated and unvaccinated groups (23.2 ± 24.6% vs. 22.6 ± 25.9%, P = 0.768), with an adjusted ß of 0.01 (95% confidence interval [CI]: -0.08-0.10). After frozen-thawed single euploid blastocyst transfer, the two groups were also comparable in clinical pregnancy rate (75.0% vs. 60.0%, P = 0.289), with an adjusted odds ratio of 6.21 (95% CI: 0.76-50.88). No significant associations were observed between vaccination and cycle characteristics or other laboratory and pregnancy outcomes. CONCLUSIONS: Inactivated SARS-CoV-2 vaccination had no detrimental impact on embryo ploidy during in vitro fertilization treatment. Our finding provides further reassurance for vaccinated women who are planning to conceive. Future prospective cohort studies with larger datasets and longer follow-up are needed to confirm the conclusion.

Two citrus KNAT-like genes, CsKN1 and CsKN2, are involved in the regulation of spring shoot development in sweet orange.

Shoot-tip abortion is a very common phenomenon in some perennial woody plants and it affects the height, architecture, and branch orientation of trees; however, little is currently known about the underlying mechanisms. In this study, we identified a gene in sweet orange (Citrus sinensis) encoding a KNAT-like protein (CsKN1) and found high expression in the shoot apical meristem (SAM). Overexpression of CsKN1 in transgenic plants prolonged the vegetative growth of SAMs, whilst silencing resulted in either the loss or inhibition of SAMs. Yeast two-hybrid analysis revealed that CsKN1 interacted with another citrus KNAT-like protein (CsKN2), and overexpression of CsKN2 in lemon and tobacco caused an extreme multiple-meristem phenotype. Overexpression of CsKN1 and CsKN2 in transgenic plants resulted in the differential expression of numerous genes related to hormone biosynthesis and signaling. Yeast one-hybrid analysis revealed that the CsKN1-CsKN2 complex can bind to the promoter of citrus floral meristem gene LEAFY (CsLFY) and inhibit its expression. These results indicated that CsKN1 might prolong the vegetative growth period of SAMs by delaying flowering. In addition, an ethylene-responsive factor (CsERF) was found to bind to the CsKN1 promoter and suppresses its transcription. Overexpression of CsERF in Arabidopsis increased the contents of ethylene and reactive oxygen species, which might induce the occurrence of shoot-tip abscission. On the basis of our results, we conclude that CsKN1 and CsKN2 might work cooperatively to regulate the shoot-tip abscission process in spring shoots of sweet orange.

Reannotation of the cultivated strawberry genome and establishment of a strawberry genome database.

Cultivated strawberry (Fragaria × ananassa) is an important fruit crop species whose fruits are enjoyed by many worldwide. An octoploid of hybrid origin, the complex genome of this species was recently sequenced, serving as a key reference genome for cultivated strawberry and related species of the Rosaceae family. The current annotation of the F. ananassa genome mainly relies on ab initio predictions and, to a lesser extent, transcriptome data. Here, we present the structure and functional reannotation of the F. ananassa genome based on one PacBio full-length RNA library and ninety-two Illumina RNA-Seq libraries. This improved annotation of the F. ananassa genome, v1.0.a2, comprises a total of 108,447 gene models, with 97.85% complete BUSCOs. The models of 19,174 genes were modified, 360 new genes were identified, and 11,044 genes were found to have alternatively spliced isoforms. Additionally, we constructed a strawberry genome database (SGD) for strawberry gene homolog searching and annotation downloading. Finally, the transcriptome of the receptacles and achenes of F. ananassa at four developmental stages were reanalyzed and qualified, and the expression profiles of all the genes in this annotation are also provided. Together, this study provides an updated annotation of the F. ananassa genome, which will facilitate genomic analyses across the Rosaceae family and gene functional studies in cultivated strawberry.

Soil N availability drives the shifts of enzyme activity and microbial phosphorus limitation in the artificial soil on cut slope in southwestern China.

The construction of highways in the subalpine mountains generates many cut slopes. Currently, the restoration of cut slope mainly focuses on the aboveground landscapes and slope stability. Yet, it remains elusive about the belowground ecosystem functions at the early stage of restoration. In this study, we evaluated the belowground ecosystem functions of cut slopes that had been restored approximately 3 years using soil enzymatic activities, microbial biomass, and stoichiometry as the proxies. The results indicated that the phenol oxidase activity was higher in cut slopes, while the activities of ß-1,4-glucosidase, ß-1,4-N-acetylglucosaminidase, leucine aminopeptidase, and acid phosphatase were lower in cut slope soils compared with natural soils. Soil nitrogen availabilities (total and/or ammonium nitrogen) showed high negative correlations with the phenol oxidase activity and positive correlations with the activities of almost all other enzymes. These results suggested that soil nitrogen was the key factor in driving the shifts of enzymatic activities across two types of soils. Moreover, we found the imbalance of soil nutrients in cut slope soils, especially the carbon vs. nitrogen and the nitrogen vs. phosphorus. By applying the vector analysis, we found that the vector A values were more than 45° in all samples, suggesting that microbial phosphorus limitation occurred in both cut slope and natural soils. These findings suggested that maintaining the balance of soil nutrient supplies is important to the recovery of the below-ground ecosystem functions at the early restoration stage of cut slopes. This study provided new insights into designing the ecological restoration strategies for cut slopes by considering the belowground ecosystem functions.

Metabolomics Insights into Oleate-Induced Disorders of Phospholipid Metabolism in Macrophages.

BACKGROUND: Diet-induced disordered phospholipid metabolism and disturbed macrophage metabolism contribute to the pathogenesis of metabolic diseases. However, the effects of oleate, a main dietary fatty acid, on macrophage phospholipid metabolism are unclear. OBJECTIVES: We aimed to discover oleate-induced disorders of macrophage phospholipid metabolism and potential therapeutic targets for treating diet-related metabolic diseases. METHODS: RAW 264.7 cells were exposed to 65 µg oleate/mL, within the blood concentration range of humans and mice, to trigger disorders of phospholipid metabolism. Meanwhile, WY-14643 and pioglitazone, 2 drugs widely used for treating metabolic diseases, were employed to prevent oleate-induced disorders of macrophage phospholipid metabolism. Subsequently, an untargeted metabolomics approach based on liquid chromatography-mass spectrometry was used to discover relevant metabolic disorders and potential therapeutic targets. RESULTS: We showed that 196 metabolites involved in phospholipid metabolism were altered upon oleate treatment and interventions of WY-14643 and pioglitazone (P < 0.05, 2-tailed Mann-Whitney U test). Notably, most lysophospholipids were decreased, whereas most phospholipids were increased in oleate-treated macrophages. Phosphatidylethanolamines accumulated most among phospholipids, and their acyl chain polyunsaturation increased in oleate-treated macrophages. Additionally, saturated fatty acids were decreased, whereas polyunsaturated fatty acids were increased in oleate-treated macrophages. Furthermore, changes in phosphatidylglycerols, phosphatidylinositols, cardiolipins, phosphatidates, lysophosphatidylglycerols, and acylcarnitines in oleate-treated macrophages could be attenuated or even abolished by WY-14643 and/or pioglitazone treatment. CONCLUSIONS: Oleate induced accumulation of various phospholipids, increased acyl chain polyunsaturation of phosphatidylethanolamines, and decreased lysophospholipids in RAW 264.7 macrophages. This study suggests macrophage phospholipid and fatty acid metabolism as potential therapeutic targets for intervening diet-related metabolic diseases.

Comparative analysis of the transcriptome, methylome, and metabolome during pollen abortion of a seedless citrus mutant.

KEY MESSAGE: Pollen abortion could be mainly attributed to abnormal meiosis in the mutant. Multiomics analysis uncovered significant epigenetic variations between the mutant and its wild type during the pollen abortion process. Male sterility caused by aborted pollen can result in seedless fruit. A seedless Ponkan mandarin mutant (bud sport) was used to compare the transcriptome, methylome, and metabolome with its progenitor to understand the mechanism of citrus pollen abortion. Cytological observations showed that the anther of the mutant could form microspore mother cells, although the microspores failed to develop fertile pollen at the anther dehiscence stage. Based on pollen phenotypic analysis, pollen abortion could be mainly attributed to abnormal meiosis in the mutant. A transcriptome analysis uncovered the molecular mechanisms underlying pollen abortion between the mutant and its wild type. A total of 5421 differentially expressed genes were identified, and some of these genes were involved in the meiosis, hormone biosynthesis and signaling, carbohydrate, and flavonoid pathways. A total of 50,845 differentially methylated regions corresponding to 15,426 differentially methylated genes in the genic region were found between the mutant and its wild type by the methylome analysis. The expression level of these genes was negatively correlated with their methylation level, especially in the promoter regions. In addition, 197 differential metabolites were identified between the mutant and its wild type based on the metabolome analysis. The transcription and metabolome analysis further indicated that the expression of genes in the flavonoid, carbohydrate, and hormone metabolic pathways was significantly modulated in the pollen of the mutant. These results indicated that demethylation may alleviate the silencing of carbohydrate genes in the mutant, resulting in excessive starch and sugar hydrolysis and thereby causing pollen abortion in the mutant.

HD-ZIP I Transcription Factor (PtHB13) Negatively Regulates Citrus Flowering through Binding to FLOWERING LOCUS C Promoter.

For floral induction in adult citrus, low temperature is one of the most important environmental factors. FLOWERING LOCUS C (FLC) plays a very important role in low-temperature-induced Arabidopsis flowering by repressed FLC expression under exposure to prolonged low-temperature conditions. However, little is known about the FLC regulation mechanism in perennial woody plants such as citrus. In this study, the functions of citrus FLC homolog (PtFLC) were investigated by ectopic expression in Arabidopsis. Transcription factor of homeodomain leucine zipper I (HD-ZIP I) as an upstream regulator of PtFLC was identified by yeast one-hybrid screen to regulate its transcription. The HD-ZIP I transcription factor was highly homologous to Arabidopsis ATHB13 and thus was named PtHB13. Ectopically expressed PtHB13 inhibited flowering in transgenic Arabidopsis. Furthermore, the expression of PtFLC and PtHB13 showed a seasonal change during the floral induction period and was also affected by low temperature. Thus, we propose that PtHB13 binds to PtFLC promoter to regulate its activity during the citrus floral induction process.

Artificial soil nutrient, aggregate stability and soil quality index of restored cut slopes along altitude gradient in southwest China.

In the subalpine mountainous region of southwest China, the artificial soil properties of restored cut slopes along the altitude gradient were studied, including available nitrogen (AN), available phosphorus (AP), available potassium (AK), urease (UR), sucrase (SC), protease (PR), catalase (CAT), texture, and aggregate stability of soil. Soil aggregatet stability by mean weight diameter (MWD), geometric mean diameter (GMD), structure failure rate (P), index of unstable aggregates (IUA) and area difference of dry and wet sieve cumulative distribution curve (ΔS) were measured and analyzed. It was found that available soil nutrients, UR, and CAT activities increased initially and then decreased, but the texture of soil was finer, and aggregate structure tended to be more stable along with an increase in the altitude gradient. The soil aggregate stability index that MWD, GMD, P, IUA, and ΔS indicated that the higher the altitude, the stability of soil aggregates was better. Principal component analysis (PCA) was used to determine the soil quality index (SQI). The obtained results from this study showed that the artificial soil quality of the cut slopes was better at a higher altitude compared to a lower altitude. These results provide a reference for the improvement of artificial soil properties of cut slopes and their quality in the future. It is necessary to pay attention to the soil quality management at a low-altitude area and reform the soil nutrients, enzyme activities, and soil structure for the restored cut slopes in the mountainous subalpine highway of southwest China.

The life span and influencing factors of metal mesh in artificial soil on railway rock-cut slopes in humid areas.

The stability of slope is strengthened by the metal mesh. The studies of the life span and influencing factors of metal mesh in the artificial soil in humid areas will guide ecological restoration of rock-cut slopes in Southwest China. Due to metal corrosion, the fixation function of the metal mesh could last for 10 years. The factors of soil contents, soil electrochemical properties and soil bacteria not only changed with the vegetation succession but also weakened the effect of the metal mesh on soil fixation for slope protection. The potential gradient, chloride ion content, sulfate ion content and water content were the main influencing factors for metal mesh corrosion during the vegetation restoration stage from 0 to 5 years, while the corrosion potential, potential gradient, chloride ion content, and water content were the main influential factors for metal mesh corrosion during the vegetation restoration stage after 11 years. At different vegetation restoration stages, the soil bacteria contained different dominant species, which had spatial heterogeneity, and the heterogeneity of the soil bacteria was another factor influencing the corrosion of the buried metal mesh. Meanwhile, the plant root as a soil fixation function strengthened with time, and 8 years later, the local woody plants gradually migrated to form a community dominated by multiple woody species. It is the first time that the life span of a metal mesh under the artificial soil of rock-cut slopes and factors affecting the different corrosion stages of the metal mesh in a humid area have been judged. The fixation function of plant root gradually replaces metal mesh, and main factors affecting the process include soil contents, soil electrochemical properties and soil bacteria. The research on corrosion factors of metal mesh under artificial soil for rock-cut slopes will contribute towards reducing the environmental risk of ecological restoration.