Identification and validation of stable reference genes for RT-qPCR analyses of Kobresia littledalei seedlings.

BACKGROUND: Kobreisa littledalei, belonging to the Cyperaceae family is the first Kobresia species with a reference genome and the most dominant species in Qinghai-Tibet Plateau alpine meadows. It has several resistance genes which could be used to breed improved crop varieties. Reverse Transcription Quantitative Real-Time Polymerase Chain Reaction (RT-qPCR) is a popular and accurate gene expression analysis method. Its reliability depends on the expression levels of reference genes, which vary by species, tissues and environments. However, K.littledalei lacks a stable and normalized reference gene for RT-qPCR analysis. RESULTS: The stability of 13 potential reference genes was tested and the stable reference genes were selected for RT-qPCR normalization for the expression analysis in the different tissues of K. littledalei under two abiotic stresses (salt and drought) and two hormonal treatments (abscisic acid (ABA) and gibberellin (GA)). Five algorithms were used to assess the stability of putative reference genes. The results showed a variation amongst the methods, and the same reference genes showed tissue expression differences under the same conditions. The stability of combining two reference genes was better than a single one. The expression levels of ACTIN were stable in leaves and stems under normal conditions, in leaves under drought stress and in roots under ABA treatment. The expression of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) expression was stable in the roots under the control conditions and salt stress and in stems exposed to drought stress. Expression levels of superoxide dismutase (SOD) were stable in stems of ABA-treated plants and in the roots under drought stress. Moreover, RPL6 expression was stable in the leaves and stems under salt stress and in the stems of the GA-treated plants. EF1-alpha expression was stable in leaves under ABA and GA treatments. The expression levels of 28 S were stable in the roots under GA treatment. In general, ACTIN and GAPDH could be employed as housekeeping genes for K. littledalei under different treatments. CONCLUSION: This study identified the best RT-qPCR reference genes for different K. littledalei tissues under five experimental conditions. ACTIN and GAPDH genes can be employed as the ideal housekeeping genes for expression analysis under different conditions. This is the first study to investigate the stable reference genes for normalized gene expression analysis of K. littledalei under different conditions. The results could aid molecular biology and gene function research on Kobresia and other related species.

Green nanopriming: responses of alfalfa (Medicago sativa L.) seedlings to alfalfa extracts capped and light-induced silver nanoparticles.

The application of nanotechnology in agriculture can remarkably improve the cultivation and growth of crop plants. Many studies showed that nanoparticles (NPs) made plants grow more vigorously. Light can make NPs aggregated, leading to the reduction of the NPs toxicity. In addition, treatment with NPs had a "hormesis effect" on plants. In this study, light-induced silver nanoparticles (AgNPs) were synthesized by using the alfalfa (Medicago sativa L.) extracts, and then the optimal synthetic condition was determined. Light-induced AgNPs were aggregated, spherical and pink, and they were coated with esters, phenols, acids, terpenes, amino acids and sugars, which were the compositions of alfalfa extracts. The concentration of free Ag+ was less than 2 % of the AgNPs concentration. Through nanopriming, Ag+ got into the seedlings and caused the impact of AgNPs on alfalfa. Compared with the control group, low concentration of light-induced AgNPs had a positive effect on the photosynthesis. It was also harmless to the leaf cells, and there was no elongation effect on shoots. Although high concentration of AgNPs was especially beneficial to root elongation, it had a slight toxic effect on seedlings due to the accumulation of silver. With the increase of AgNPs concentration, the content of silver in the seedlings increased and the silver enriched in plants was at the mg/kg level. Just as available research reported the toxicity of NPs can be reduced by using suitable synthesis and application methods, the present light induction, active material encapsulation and nanopriming minimized the toxicity of AgNPs to plants, enhancing the antioxidant enzyme system.

Analysis of risk factors for early death in patients with acute promyelocytic leukaemia treated with arsenic trioxide.

To date, no specific studies have evaluated early death (ED) in patients with acute promyelocytic leukaemia (APL) homogeneously treated with arsenic trioxide induction therapy and investigated according to the white blood cell (WBC) count at onset. Such patients were retrospectively analysed in this study, including 314 patients with a WBC count ≤ 10 × 109/L (standard-risk (SR) group) and 144 with a WBC count > 10 × 109/L (high-risk (HR) group). The baseline clinical characteristics and risk factors for ED were compared between the two groups. The incidence of fibrinogen < 1.0 g/L and elevated serum uric acid, aspartate aminotransferase and creatinine levels were higher in the HR group than in the SR group (P = 0.001; P < 0.001; P < 0.001; P = 0.044, respectively). The ED rate was significantly higher in the HR group than in the SR group (29.17% vs. 10.83%, P < 0.001). The main cause of ED was bleeding, followed by infection and differentiation syndrome (DS) in the HR group, while it was bleeding, followed by DS and infection in the SR group. Male sex, age > 50 years old, and fibrinogen < 1.0 g/L were independent risk factors for ED in the SR group. Increased serum creatinine levels, decreased albumin levels, and fibrinogen < 1.0 g/L were independent risk factors for ED in the HR group. Overall, the incidence of ED was higher in the HR group, and the baseline clinical characteristics, causes, times, and predictors of ED in the HR group differed from those in the SR group.

Effects of MiR-214-3p Regulation of SERCA2a Expression on Contractility of Cardiomyocytes in Heart Failure Model.

This study aimed to explore the targeted regulation of microRNA-214-3p (miR-214-3p) on sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPase 2a (SERCA2a) and its mechanism on heart failure (HF). In this study, a rat model of HF was established by injecting isoproterenol to detect the changes in heart function. Then the primary rat cardiomyocytes were extracted and cultured. The cells were divided into the normal group, HF model group, miR-214-3p mimic group, and inhibitor group according to treatment methods. The expression differences of SERCA2a in each group were detected. The binding sites of miR-214-3p and SERCA2a were predicted, wild-type or mutant SERCA2a was prepared and co-transfected into cardiomyocytes with mimic, and the targeting effect was detected by the dual-luciferase reporter gene. Finally, the systolic function of each group was detected by a single-cell systolic dynamic edge detection system. The results showed that cardiac output and left ventricular ejection fraction of HF rats were significantly lower than those of normal rats (P<0.05). The results of the cell test showed that messenger ribonucleic acid (mRNA) and protein expression levels of SERCA2a in the model group and the mimic group were significantly lower than those in the mimic group (P<0.05), but there were no differences between normal group and inhibitor group (P>0.05). Target prediction revealed that miR-214-3p had a complementary pairing of 6 bases with the SERCA2a 3'non-coding region. After co-transfection with miR-214-3p mimic and wild-type SERCA2a expression vector, the dual-luciferase activity was significantly decreased (P<0.05). The percentage of maximal contraction amplitude, peak contraction time, and 50% diastolic time of cells in the model group and mimic group decreased significantly. The mimic group was significantly smaller (P<0.05), but there were no differences between the normal group and the inhibitor group (P>0.05). These results indicated that SERCA2a expression was significantly reduced in HF cells, and miR-214-3p could inhibit SERCA2a expression by targeting the SERCA2a 3'UTR region. Inhibition of miR-214-3p could promote the expression of SERCA2a, which in turn promoted the contractile function of HF rat cardiomyocytes.

Identification of Competing Endogenous RNAs (ceRNAs) Network Associated with Drought Tolerance in Medicago truncatula with Rhizobium Symbiosis.

Drought, bringing the risks of agricultural production losses, is becoming a globally environmental stress. Previous results suggested that legumes with nodules exhibited superior drought tolerance compared with the non-nodule group. To investigate the molecular mechanism of rhizobium symbiosis impacting drought tolerance, transcriptome and sRNAome sequencing were performed to identify the potential mRNA-miRNA-ncRNA dynamic network. Our results revealed that seedlings with active nodules exhibited enhanced drought tolerance by reserving energy, synthesizing N-glycans, and medicating systemic acquired resistance due to the early effects of symbiotic nitrogen fixation (SNF) triggered in contrast to the drought susceptible with inactive nodules. The improved drought tolerance might be involved in the decreased expression levels of miRNA such as mtr_miR169l-5p, mtr_miR398b, and mtr_miR398c and its target genes in seedlings with active nodules. Based on the negative expression pattern between miRNA and its target genes, we constructed an mRNA-miR169l-ncRNA ceRNA network. During severe drought stress, the lncRNA alternative splicings TCONS_00049507 and TCONS_00049510 competitively interacted with mtr_miR169l-5p, which upregulated the expression of NUCLEAR FACTOR-Y (NF-Y) transcription factor subfamily NF-YA genes MtNF-YA2 and MtNF-YA3 to regulate their downstream drought-response genes. Our results emphasized the importance of SNF plants affecting drought tolerance. In conclusion, our work provides insight into ceRNA involvement in rhizobium symbiosis contributing to drought tolerance and provides molecular evidence for future study.

MDP25 mediates the fine-tuning of microtubule organization in response to salt stress.

Microtubules are dynamic cytoskeleton structures playing fundamental roles in plant responses to salt stress. The precise mechanisms by which microtubule organization is regulated under salt stress are largely unknown. Here, we report that Arabidopsis thaliana MICROTUBULE-DESTABILIZING PROTEIN 25 (MDP25; also known as PLASMA MEMBRANE-ASSOCIATED CATION-BINDING PROTEIN 1 (PCaP1)) helps regulate microtubule organization. Under salt treatment, elevated cytosolic Ca2+ concentration caused MDP25 to partially dissociate from the plasma membrane, promoting microtubule depolymerization. When Ca2+ signaling was blocked by BAPTA-AM or LaCl3 , microtubule depolymerization in wild-type and MDP25-overexpressing cells was slower, while there was no obvious change in mdp25 cells. Knockout of MDP25 improved microtubule reassembly and was conducive to microtubule integrity under long-term salt treatment and microtubule recovery after salt stress. Moreover, mdp25 seedlings exhibited a higher survival rate under salt stress. The presence microtubule-disrupting reagent oryzalin or microtubule-stabilizing reagent paclitaxel differentially affected the survival rates of different genotypes under salt stress. MDP25 promoted microtubule instability by affecting the catastrophe and rescue frequencies, shrinkage rate and time in pause phase at the microtubule plus-end and the depolymerization rate at the microtubule minus-end. These findings reveal a role for MDP25 in regulating microtubule organization under salt treatment by affecting microtubule dynamics.

Addressing the challenge of cold stress resilience with the synergistic effect of Rhizobium inoculation and exogenous melatonin application in Medicago truncatula.

Cold stress is an adverse environmental condition that limits the growth and yield of leguminous plants. Thus, discovering an effective way of ameliorating cold-mediated damage is important for sustainable legume production. In this study, the combined use of Rhizobium inoculation (RI) and melatonin (MT) pretreatment was investigated in Medicago truncatula plants under cold stress. Eight-week-old seedlings were divided into eight groups: (i) CK (no stress, noninoculated, no MT), (ii) RI (Rhizobium inoculated), (iii) MT (75 µM melatonin), (iv) RI+MT, (v) CS (cold stress at 4 °C without Rhizobium inoculation and melatonin), (vi) CS+RI, (vii) CS+MT, and (viii) CS+RI+MT. Plants were exposed to cold stress for 24 hrs. Cold stress decreased photosynthetic pigments and increased oxidative stress. Pretreatment with RI and MT alone or combined significantly improved root activity and plant biomass production under cold stress. Interestingly, chlorophyll contents increased by 242.81% and MDA levels dramatically decreased by 34.22% in the CS+RI+MT treatment compared to the CS treatment. Moreover, RI+MT pretreatment improved the antioxidative ability by increasing the activities of peroxidase (POD; 8.45%), superoxide dismutase (SOD; 50.36%), catalase (CAT; 140.26%), and ascorbate peroxidase (APX; 42.63%) over CS treated plants. Additionally, increased osmolyte accumulation, nutrient uptake, and nitrate reductase activity due to the combined use of RI and MT helped the plants counteract cold-mediated damage by strengthening the nonenzymatic antioxidant system. These data indicate that pretreatment with a combined application of RI and MT can attenuate cold damage by enhancing the antioxidation ability of legumes.

Drought stress and plant ecotype drive microbiome recruitment in switchgrass rhizosheath.

The rhizosheath, a layer of soil grains that adheres firmly to roots, is beneficial for plant growth and adaptation to drought environments. Switchgrass is a perennial C4 grass which can form contact rhizosheath under drought conditions. In this study, we characterized the microbiomes of four different rhizocompartments of two switchgrass ecotypes (Alamo and Kanlow) grown under drought or well-watered conditions via 16S ribosomal RNA amplicon sequencing. These four rhizocompartments, the bulk soil, rhizosheath soil, rhizoplane, and root endosphere, harbored both distinct and overlapping microbial communities. The root compartments (rhizoplane and root endosphere) displayed low-complexity communities dominated by Proteobacteria and Firmicutes. Compared to bulk soil, Cyanobacteria and Bacteroidetes were selectively enriched, while Proteobacteria and Firmicutes were selectively depleted, in rhizosheath soil. Taxa from Proteobacteria or Firmicutes were specifically selected in Alamo or Kanlow rhizosheath soil. Following drought stress, Citrobacter and Acinetobacter were further enriched in rhizosheath soil, suggesting that rhizosheath microbiome assembly is driven by drought stress. Additionally, the ecotype-specific recruitment of rhizosheath microbiome reveals their differences in drought stress responses. Collectively, these results shed light on rhizosheath microbiome recruitment in switchgrass and lay the foundation for the improvement of drought tolerance in switchgrass by regulating the rhizosheath microbiome.

Effects of shade stress on turfgrasses morphophysiology and rhizosphere soil bacterial communities.

BACKGROUND: The shade represents one of the major environmental limitations for turfgrass growth. Shade influences plant growth and alters plant metabolism, yet little is known about how shade affects the structure of rhizosphere soil microbial communities and the role of soil microorganisms in plant shade responses. In this study, a glasshouse experiment was conducted to examine the impact of shade on the growth and photosynthetic capacity of two contrasting shade-tolerant turfgrasses, shade-tolerant dwarf lilyturf (Ophiopogon japonicus, OJ) and shade-intolerant perennial turf-type ryegrass (Lolium perenne, LP). We also examined soil-plant feedback effects on shade tolerance in the two turfgrass genotypes. The composition of the soil bacterial community was assayed using high-throughput sequencing. RESULTS: OJ maintained higher photosynthetic capacity and root growth than LP under shade stress, thus OJ was found to be more shade-tolerant than LP. Shade-intolerant LP responded better to both shade and soil microbes than shade-tolerant OJ. The shade and live soil decreased LP growth, but increased biomass allocation to shoots in the live soil. The plant shade response index of LP is higher in live soil than sterile soil, driven by weakened soil-plant feedback under shade stress. In contrast, there was no difference in these values for OJ under similar shade and soil treatments. Shade stress had little impact on the diversity of the OJ and the LP bacterial communities, but instead impacted their composition. The OJ soil bacterial communities were mostly composed of Proteobacteria and Acidobacteria. Further pairwise fitting analysis showed that a positive correlation of shade-tolerance in two turfgrasses and their bacterial community compositions. Several soil properties (NO3--N, NH4+-N, AK) showed a tight coupling with several major bacterial communities under shade stress. Moreover, OJ shared core bacterial taxa known to promote plant growth and confer tolerance to shade stress, which suggests common principles underpinning OJ-microbe interactions. CONCLUSION: Soil microorganisms mediate plant responses to shade stress via plant-soil feedback and shade-induced change in the rhizosphere soil bacterial community structure for OJ and LP plants. These findings emphasize the importance of understanding plant-soil interactions and their role in the mechanisms underlying shade tolerance in shade-tolerant turfgrasses.

Fertility-related interplay between fungal guilds underlies plant richness-productivity relationships in natural grasslands.

The plant richness-productivity relationship is a central subject in ecology, yet the mechanisms behind this pattern remain debated. Soil fungi are closely associated with the dynamics of plant communities, however empirical evidence on how fungal communities integrate into the richness-productivity relationships of natural environments is lacking. We used Illumina high-throughput sequencing to identify rhizosphere fungal communities across a natural plant richness gradient at two sites with different fertility conditions, and related the subsequent information to plant richness and productivity to elucidate the role of fungal guilds in integrating the linkages of both plant components. Saprotrophs, mycorrhizal fungi and potential plant pathogens interacted differently between the sites, with saprotrophic and mycorrhizal fungal abundances being positively correlated at the high-nutrient site and abundances of mycorrhizal fungi and potential plant pathogens being negatively correlated at the low-nutrient site. The synergistic associations between these fungal guilds with plant richness and productivity operated in concert to promote positive richness-productivity relationships. Our findings provide empirical evidence for the importance of soil fungal guilds in integrating the linkages of plant richness and productivity, and suggest that future work incorporating soil fungal communities into richness-productivity relationships would advance our mechanistic understanding of their linkages.

Hydrotropism in the primary roots of maize.

Recent studies mainly in Arabidopsis have renewed interest and discussion in some of the key issues in hydrotropism of roots, such as the site of water sensing and the involvement of auxin. We examined hydrotropism in maize (Zea mays) primary roots. We determined the site of water sensing along the root using a nonintrusive method. Kinematic analysis was conducted to investigate spatial root elongation during hydrotropic response. Indole-3-acetic acid (IAA) and other hormones were quantified using LC-MS/MS. The transcriptome was analyzed using RNA sequencing. Main results: The very tip of the root is the most sensitive to the hydrostimulant. Hydrotropic bending involves coordinated adjustment of spatial cell elongation and cell flux. IAA redistribution occurred in maize roots, preceding hydrotropic bending. The redistribution is caused by a reduction of IAA content on the side facing a hydrostimulant, resulting in a higher IAA content on the dry side. Transcriptomic analysis of the elongation zone prior to bending identified IAA response and lignin synthesis/wall cross-linking as some of the key processes occurring during the early stages of hydrotropic response. We conclude that maize roots differ from Arabidopsis in the location of hydrostimulant sensing and the involvement of IAA redistribution.

Fecal microbiota of lambs fed purple prairie clover (Dalea purpurea Vent.) and alfalfa (Medicago sativa).

The present study assessed the effect of purple prairie clover (PPC) and PPC condensed tannins (CT) on the fecal microbiota of lambs using high-throughput 16S rRNA gene pyrosequencing. A total of 18 individual lambs were randomly divided into three groups and fed either green chop alfalfa (Alf), a 40:60 (DM basis; Mix) mixture of Alf and PPC, or Mix supplemented with polyethylene glycol (Mix-P) for 18 days. Fecal samples were collected on days 13 through 18 using digital rectal retrieval. The DNA of fecal samples was extracted and the microbial 16S rRNA gene amplicons were sequenced using 454 pyrosequencing. Regardless of diet, the bacterial community was dominated by Firmicutes and Bacteroidetes with many sequences unclassified at the genus level. Forage type and CT had no effect on the fecal microbial composition at the phylum level or on α-diversity. Compared to the Alf diet, the Mix diet reduced the relative abundance of Akkermansia (P = 0.03) and Asteroleplasma (P = 0.05). Fecal microbial populations in Alf and Mix-P clustered separately from each other when assessed using unweighted UniFrac (P < 0.05). These results indicate that PPC CT up to 36 g/kg DM in the diet had no major effect on fecal microbial flora at the phyla level and exerted only minor effects on the genera composition of fecal microbiota in lambs.

De novo transcriptome sequencing and gene expression profiling of Elymus nutans under cold stress.

BACKGROUND: Elymus nutans Griseb., is an important alpine perennial forage of Pooideae subfamily with strong inherited cold tolerance. To get a deeper insight into its molecular mechanisms of cold tolerance, we compared the transcriptome profiling by RNA-Seq in two genotypes of Elymus nutans Griseb. the tolerant Damxung (DX) and the sensitive Gannan (GN) under cold stress. RESULTS: The new E. nutans transcriptomes were assembled and comprised 200,520 and 181,331 transcripts in DX and GN, respectively. Among them, 5436 and 4323 genes were differentially expressed in DX and GN, with 170 genes commonly expressed over time. Early cold responses involved numerous genes encoding transcription factors and signal transduction in both genotypes. The AP2/EREBP famliy of transcription factors was predominantly expressed in both genotypes. The most significant transcriptomic changes in the later phases of cold stress are associated with oxidative stress, primary and secondary metabolism, and photosynthesis. Higher fold expressions of fructan, trehalose, and alpha-linolenic acid metabolism-related genes were detected in DX. The DX-specific dehydrins may be promising candidates to improve cold tolerance. Twenty-six hub genes played a central role in both genotypes under cold stress. qRT-PCR analysis of 26 genes confirmed the RNA-Seq results. CONCLUSIONS: The stronger transcriptional differentiation during cold stress in DX explains its better cold tolerance compared to GN. The identified fructan biosynthesis, alpha-linolenic acid metabolism, and DX-specific dehydrin-related genes may provide genetic resources for the improvement of cold-tolerant characters in DX. Our findings provide important clues for further studies of the molecular mechanisms underlying cold stress responses in plants.

MsZEP, a novel zeaxanthin epoxidase gene from alfalfa (Medicago sativa), confers drought and salt tolerance in transgenic tobacco.

KEY MESSAGE: The zeaxanthin epoxidase gene ( MsZEP ) was cloned and characterized from alfalfa and validated for its function of tolerance toward drought and salt stresses by heterologous expression in Nicotiana tabacum. Zeaxanthin epoxidase (ZEP) plays important roles in plant response to various environment stresses due to its functions in ABA biosynthetic and the xanthophyll cycle. To understand the expression characteristics and the biological functions of ZEP in alfalfa (Medicago sativa), a novel gene, designated as MsZEP (KM044311), was cloned, characterized and overexpressed in Nicotiana tabacum. The open reading frame of MsZEP contains 1992 bp nucleotides and encodes a 663-amino acid polypeptide. Amino acid sequence alignment indicated that deduced MsZEP protein was highly homologous to other plant ZEP sequences. Phylogenetic analysis showed that MsZEP was grouped into a branch with other legume plants. Real-time quantitative PCR revealed that MsZEP gene expression was clearly tissue-specific, and the expression levels were higher in green tissues (leaves and stems) than in roots. MsZEP expression decreased in shoots under drought, cold, heat and ABA treatment, while the expression levels in roots showed different trends. Besides, the results showed that nodules could up-regulate the MsZEP expression under non-stressful conditions and in the earlier stage of different abiotic stress. Heterologous expression of the MsZEP gene in N. tabacum could confer tolerance to drought and salt stress by affecting various physiological pathways, ABA levels and stress-responsive genes expression. Taken together, these results suggested that the MsZEP gene may be involved in alfalfa responses to different abiotic stresses and nodules, and could enhance drought and salt tolerance of transgenic tobacco by heterologous expression.

Piceatannol promotes apoptosis via up-regulation of microRNA-129 expression in colorectal cancer cell lines.

Piceatannol, a naturally occurring analog of resveratrol, has been confirmed as an antitumor agent by inhibiting proliferation, migration, and metastasis in diverse cancer. However, the effect and mechanisms of piceatannol on colorectal cancer (CRC) have not been well understood. This study aimed to test whether piceatannol could inhibit growth of CRC cells and reveal its underlying molecular mechanism. MTT assay was used to detect the cell viability in HCT116 and HT29 cells. Flow cytometry analysis was employed to measure apoptosis of CRC cells. Bcl-2, Bax and caspase-3 levels were analyzed by Western blot and miR-129 levels were determined by real-time RT-PCR. Our study showed that piceatannol inhibited HCT116 and HT29 cells growth in a concentration- and time-dependent manner. Piceatannol induced apoptosis by promoting expression of miR-129, and then inhibiting expression of Bcl-2, an known target for miR-129. Moreover, knock down of miR-129 could reverse the reduction of cell viability induced by piceatannol in HCT116 and HT29 cells. Taken together, our study unraveled the ability of piceatannol to suppress colorectal cancer growth and elucidated the participation of miR-129 in the anti-cancer action of piceatannol. Our findings suggest that piceatannol can be considered to be a promising anticancer agent for CRC.

Insights into the Impact of Trans-Zeatin Overproduction-Engineered Sinorhizobium meliloti on Alfalfa (Medicago sativa L.) Tolerance to Drought Stress.

Plant growth-promoting rhizobacteria have been shown to enhance plant tolerance to drought stress through various mechanisms. However, there is limited research on improving drought resistance in alfalfa by genetically modifying PGPR to produce increased levels of cytokinins. Herein, we employed synthetic biology approaches to engineer two novel strains of Sinorhizobium meliloti capable of overproducing trans-Zeatin and investigated their potential in enhancing drought tolerance in alfalfa. Our results demonstrate that alfalfa plants inoculated with these engineered S. meliloti strains exhibited reduced wilting and yellowing while maintaining higher relative water content under drought conditions. The engineered S. meliloti-induced tZ activated the activity of antioxidant enzymes and the accumulation of osmolytes. Additionally, the increased endogenous tZ content in plants alleviated the impact of drought stress on the alfalfa photosynthetic rate. However, under nondrought conditions, inoculation with the engineered S. meliloti strains had no significant effect on alfalfa biomass and nodule formation.

Genome assembly and multi-omic analyses reveal the mechanisms underlying flower color formation in Torenia fournieri.

Torenia fournieri Lind. is an ornamental plant that is popular for its numerous flowers and variety of colors. However, its genomic evolutionary history and the genetic and metabolic bases of flower color formation remain poorly understood. Here, we report the first T. fournieri reference genome, which was resolved to the chromosome scale and was 164.4 Mb in size. Phylogenetic analyses clarified relationships with other plant species, and a comparative genomic analysis indicated that the shared ancestor of T. fournieri and Antirrhinum majus underwent a whole genome duplication event. Joint transcriptomic and metabolomic analyses identified many metabolites related to pelargonidin, peonidin, and naringenin production in rose (TfR)-colored flowers. Samples with blue (TfB) and deep blue (TfD) colors contained numerous derivatives of petunidin, cyanidin, quercetin, and malvidin; differences in the abundances of these metabolites and expression levels of the associated genes were hypothesized to be responsible for variety-specific differences in flower color. Furthermore, the genes encoding flavonoid 3-hydroxylase, anthocyanin synthase, and anthocyanin reductase were differentially expressed between flowers of different colors. Overall, we successfully identified key genes and metabolites involved in T. fournieri flower color formation. The data provided by the chromosome-scale genome assembly establish a basis for understanding the differentiation of this species and will facilitate future genetic studies and genomic-assisted breeding.

Depressive disorders among children in the transforming China: an epidemiological survey of prevalence, correlates, and service use.

BACKGROUND: To date, no one-phase survey of childhood depression has been performed in China that involves both urban and rural community children. The objective of this study was to determine the prevalence, correlates, and mental health service utilization of depressive disorders (DDs) in a community-based sample of 6-14-year-old children in south-central China. METHODS: Children (3,582) were approached through multistage sampling and interviewed using a Chinese version of the Mini International Neuropsychiatric Interview for Children and Adolescents 5.0, which is a structured interview that is administered by trained psychiatrists to obtain information from children and their guardians. RESULTS: The overall prevalence of all current DDs was found to be 2.8% (95%CI: 1.5-3.9). The risk factors for depression included being 9-14-year old, not attending school, having unmarried parents, living in a non-nuclear family (single parent or parentless family), being taken care of by people other than two parents (single parent, grandparent(s), other relatives, or others) during the past year, and not being breastfed prior to 1 year of age. Only 5.8% of the depressed children had received professional help prior to the interview. CONCLUSIONS: The prevalence of DDs among children in this part of China is relatively high compared with most figures reported in other countries. Depression in this age group has been a major public health concern, but it is often underrecognized. There is an urgent need to develop efficacious interventions aimed at the prevention and early recognition of childhood depression.

Photosynthesis, Water Status and K+/Na+ Homeostasis of Buchoe dactyloides Responding to Salinity.

Soil salinization is one of the most serious abiotic stresses restricting plant growth. Buffalograss is a C4 perennial turfgrass and forage with an excellent resistance to harsh environments. To clarify the adaptative mechanisms of buffalograss in response to salinity, we investigated the effects of NaCl treatments on photosynthesis, water status and K+/Na+ homeostasis of this species, then analyzed the expression of key genes involved in these processes using the qRT-PCR method. The results showed that NaCl treatments up to 200 mM had no obvious effects on plant growth, photosynthesis and leaf hydrate status, and even substantially stimulated root activity. Furthermore, buffalograss could retain a large amount of Na+ in roots to restrict Na+ overaccumulation in shoots, and increase leaf K+ concentration to maintain a high K+/Na+ ratio under NaCl stresses. After 50 and 200 mM NaCl treatments, the expressions of several genes related to chlorophyll synthesis, photosynthetic electron transport and CO2 assimilation, as well as aquaporin genes (BdPIPs and BdTIPs) were upregulated. Notably, under NaCl treatments, the increased expression of BdSOS1, BdHKT1 and BdNHX1 in roots might have helped Na+ exclusion by root tips, retrieval from xylem sap and accumulation in root cells, respectively; the upregulation of BdHAK5 and BdSKOR in roots likely enhanced K+ uptake and long-distance transport from roots to shoots, respectively. This work finds that buffalograss possesses a strong ability to sustain high photosynthetic capacity, water balance and leaf K+/Na+ homeostasis under salt stress, and lays a foundation for elucidating the molecular mechanism underlying the salt tolerance of buffalograss.

A 3-Ketoacyl-CoA Synthase 10 (KCS10) Homologue from Alfalfa Enhances Drought Tolerance by Regulating Cuticular Wax Biosynthesis.

Cuticular wax, forming the first line of defense against adverse environmental stresses, comprises very long-chain fatty acids (VLCFAs) and their derivatives. 3-Ketoacyl-CoA synthase (KCS) is a rate-limiting enzyme for VLCFA biosynthesis. In this study, we isolated KCS10, a KCS gene from alfalfa, and analyzed the effect of gene expression on wax production and drought stress in transgenic plants. MsKCS10 overexpression increased compact platelet-like crystal deposition and promoted primary alcohol biosynthesis through acyl reduction pathways in alfalfa leaves. Overexpression of MsKCS10 induced the formation of coiled-rodlet-like crystals and increased n-alkane content through decarbonylation pathways in tobacco and tomato fruits. Overexpression of MsKCS10 enhanced drought tolerance by limiting nonstomatal water loss, improving photosynthesis, and maintaining osmotic potential under drought stress in transgenic tobacco. In summary, MsKCS10 plays an important role in wax biosynthesis, wax crystal morphology, and drought tolerance, although the mechanisms are different among the plant species. MsKCS10 can be targeted in future breeding programs to improve drought tolerance in plants.