ZmERF21 directly regulates hormone signaling and stress-responsive gene expression to influence drought tolerance in maize seedlings.

Drought stress adversely impacts crop development and yield. Maize frequently encounters drought stress during its life cycle. Improvement of drought tolerance is a priority of maize breeding programs. Here, we identified a novel transcription factor encoding gene, APETALA2 (AP2)/Ethylene response factor (ERF), which is tightly associated with drought tolerance in maize seedlings. ZmERF21 is mainly expressed in the root and leaf and it can be highly induced by polyethylene glycol treatment. Genetic analysis showed that the zmerf21 mutant plants displayed a reduced drought tolerance phenotype, accompanied by phenotypical and physiological changes that are commonly observed in drought conditions. Overexpression of ZmERF21 in maize significantly increased the chlorophyll content and activities of antioxidant enzymes under drought conditions. RNA-Seq and DNA affinity purification sequencing analysis further revealed that ZmERF21 may directly regulate the expression of genes related to hormone (ethylene, abscisic acid) and Ca signaling as well as other stress-response genes through binding to the promoters of potential target genes. Our results thereby provided molecular evidence of ZmERF21 is involved in the drought stress response of maize.

A New Role for Conivaptan in Ulcerative Colitis in Mice: Inhibiting Differentiation of CD4+T Cells into Th1 Cells.

BACKGROUND: Conivaptan, a nonselective antagonist of vasopressin receptors V1a and V2, is the first drug of this class to be used for treating euvolemic and hypervolemic hyponatremia. Recently, increasing evidence supports the involvement of vasopressin in immune responses. AIMS: In this study, we investigated the effect of conivaptan on the modulation of CD4+ T cell homeostasis and the progression of experimental colitis. METHODS: The expression of the V1a receptor on CD4+ T cells was detected by immunofluorescence and western blot. The subset of isolated CD4+ T cells were examined after arginine vasopressin (AVP) incubation. CD4+ T cells were injected into DNBS-induced mice through the tail vein. The severity of colitis was evaluated according to weight, disease activity index (DAI), and morphological injury. Intracellular Ca2+ ([Ca2+]i) signaling in CD4+ T cells was measured using the Fluo-3 AM loading method. T-bet and IFN-γ mRNAs in the colon were detected by real-time polymerase chain reaction (qPCR). RESULTS: We found that CD4+ T cells expressed the V1a receptor. Activation of the V1a receptor significantly promoted the differentiation of CD4+ T cells into T helper 1 (Th1) cells. This process was blocked by conivaptan treatment. However, the activation of the V1a receptor did not evoke an increase in [Ca2+]i in CD4+ T cells. Notably, conivaptan markedly alleviated body weight loss, pathological damage, and expression of T-bet and IFN-γ in the colon of DNBS-treated mice. CONCLUSIONS: For the first time, we report that conivaptan attenuated colitis by inhibiting the differentiation of CD4+ T cells into Th1 cells. Mechanistically, the anti-inflammatory role of conivaptan is independent of [Ca2+]i.

ZmCCT regulates photoperiod-dependent flowering and response to stresses in maize.

BACKGROUND: Appropriate flowering time is very important to the success of modern agriculture. Maize (Zea mays L.) is a major cereal crop, originated in tropical areas, with photoperiod sensitivity. Which is an important obstacle to the utilization of tropical/subtropical germplasm resources in temperate regions. However, the study on the regulation mechanism of photoperiod sensitivity of maize is still in the early stage. Although it has been previously reported that ZmCCT is involved in the photoperiod response and delays maize flowering time under long-day conditions, the underlying mechanism remains unclear. RESULTS: Here, we showed that ZmCCT overexpression delays flowering time and confers maize drought tolerance under LD conditions. Implementing the Gal4-LexA/UAS system identified that ZmCCT has a transcriptional inhibitory activity, while the yeast system showed that ZmCCT has a transcriptional activation activity. DAP-Seq analysis and EMSA indicated that ZmCCT mainly binds to promoters containing the novel motifs CAAAAATC and AAATGGTC. DAP-Seq and RNA-Seq analysis showed that ZmCCT could directly repress the expression of ZmPRR5 and ZmCOL9, and promote the expression of ZmRVE6 to delay flowering under long-day conditions. Moreover, we also demonstrated that ZmCCT directly binds to the promoters of ZmHY5, ZmMPK3, ZmVOZ1 and ZmARR16 and promotes the expression of ZmHY5 and ZmMPK3, but represses ZmVOZ1 and ZmARR16 to enhance stress resistance. Additionally, ZmCCT regulates a set of genes associated with plant development. CONCLUSIONS: ZmCCT has dual functions in regulating maize flowering time and stress response under LD conditions. ZmCCT negatively regulates flowering time and enhances maize drought tolerance under LD conditions. ZmCCT represses most flowering time genes to delay flowering while promotes most stress response genes to enhance stress tolerance. Our data contribute to a comprehensive understanding of the regulatory mechanism of ZmCCT in controlling maize flowering time and stress response.

Large-scale reconstruction of chromatin structures of maize temperate and tropical inbred lines.

Maize is a model plant species often used for genetics and genomics research because of its genetic diversity. There are prominent morphological, genetic, and epigenetic variations between tropical and temperate maize lines. However, the genome-wide chromatin conformations of these two maize types remain unexplored. We applied a Hi-C approach to compare the genome-wide chromatin interactions between temperate inbred line D132 and tropical line CML288. A reconstructed maize three-dimensional genome model revealed the spatial segregation of the global A and B compartments. The A compartments contain enriched genes and active epigenome marks, whereas the B compartments are gene-poor, transcriptionally silent chromatin regions. Whole-genome analyses indicated that the global A compartment content of CML288 was 3.12% lower than that of D132. Additionally, global and A/B sub-compartments were associated with differential gene expression and epigenetic changes between two inbred lines. About 25.3% of topologically associating domains (TADs) were determined to be associated with complex domain-level modifications that induced transcriptional changes, indicative of a large-scale reorganization of chromatin structures between the inbred maize lines. Furthermore, differences in chromatin interactions between the two lines correlated with epigenetic changes. These findings provide a solid foundation for the wider plant community to further investigate the genome-wide chromatin structures in other plant species.

Identification of ZmNF-YC2 and its regulatory network for maize flowering time.

Flowering time is an important agronomic trait that determines the distribution and adaptation of plants. The accurate prediction of flowering time in elite germplasm is critical for maize breeding. However, the molecular mechanisms underlying the photoperiod response remain elusive in maize. Here we cloned the flowering time-controlling gene, ZmNF-YC2, by map-based cloning and confirmed that ZmNF-YC2 is the nuclear transcription factor Y subunit C-2 protein and a positive regulator of flowering time in maize under long-day conditions. Our results show that ZmNF-YC2 promotes the expression of ZmNF-YA3. ZmNF-YA3 negatively regulates the transcription of ZmAP2. ZmAP2 suppresses the expression of ZMM4 to delay flowering time. We then developed a gene regulatory model of flowering time in maize using ZmNF-YC2, ZmNF-YA3, ZmAP2, ZMM4, and other key genes. The cascading regulation by ZmNF-YC2 of maize flowering time has not been reported in other species.

CLA4 regulates leaf angle through multiple hormone signaling pathways in maize.

Leaf angle is an important agronomic trait in cereals and shares a close relationship with crop architecture and grain yield. Although it has been previously reported that ZmCLA4 can influence leaf angle, the underlying mechanism remains unclear. In this study, we used the Gal4-LexA/UAS system and transactivation analysis to demonstrate in maize (Zea mays) that ZmCLA4 is a transcriptional repressor that regulates leaf angle. DNA affinity purification sequencing (DAP-Seq) analysis revealed that ZmCLA4 mainly binds to promoters containing the EAR motif (CACCGGAC) as well as to two other motifs (CCGARGS and CDTCNTC) to inhibit the expression of its target genes. Further analysis of ZmCLA4 target genes indicated that ZmCLA4 functions as a hub of multiple plant hormone signaling pathways: ZmCLA4 was found to directly bind to the promoters of multiple genes including ZmARF22 and ZmIAA26 in the auxin transport pathway, ZmBZR3 in the brassinosteroid signaling pathway, two ZmWRKY genes involved in abscisic acid metabolism, ZmCYP genes (ZmCYP75B1, ZmCYP93D1) related to jasmonic acid metabolism, and ZmABI3 involved in the ethylene response pathway. Overall, our work provides deep insights into the ZmCLA4 regulatory network in controlling leaf angle in maize.

Oxytocin signalling in dendritic cells regulates immune tolerance in the intestine and alleviates DSS-induced colitis.

BACKGROUND: Ulcerative colitis (UC) is a type of inflammatory bowel disease (IBD) that is associated with immune dysfunction. Recent studies have indicated that the neurosecretory hormone oxytocin (OXT) has been proven to alleviate experimental colitis. METHODS: We investigated the role of OXT/OXT receptor (OXTR) signalling in dendritic cells (DCs) using mice with specific OXTR deletion in CD11c+ cells (OXTRflox/flox×CD11c-cre mice) and a dextran sulfate sodium (DSS)-induced colitis model. RESULTS: The level of OXT was abnormal in the serum or colon tissue of DSS-induced colitis mice or the plasma of UC patients. Both bone marrow-derived DCs (BMDCs) and lamina propria DCs (LPDCs) express OXTR. Knocking out OXTR in DCs exacerbated DSS-induced acute and chronic colitis in mice. In contrast, the injection of OXT-pretreated DCs significantly ameliorated colitis. Mechanistically, OXT prevented DC maturation through the phosphatidylinositol 4,5-bisphosphate 3-kinase (Pi3K)/AKT pathway and promoted phagocytosis, adhesion and cytokine modulation in DCs. Furthermore, OXT pre-treated DCs prevent CD4+ T cells differentiation to T helper 1 (Th1) and Th17. CONCLUSIONS: Our results suggest that OXT-induced tolerogenic DCs efficiently protect against experimental colitis via Pi3K/AKT pathway. Our work provides evidence that the nervous system participates in the immune regulation of colitis by modulating DCs. Our findings suggest that generating ex vivo DCs pretreated with OXT opens new therapeutic perspectives for the treatment of UC in humans.

MicroRNA transcriptomic analysis of the sixth leaf of maize (Zea mays L.) revealed a regulatory mechanism of jointing stage heterosis.

BACKGROUND: Zhengdan 958 (Zheng 58 × Chang 7-2), a commercial hybrid that is produced in a large area in China, is the result of the successful use of the heterotic pattern of Reid × Tang-SPT. The jointing stage of maize is the key period from vegetative to reproductive growth, which determines development at later stages and heterosis to a certain degree. MicroRNAs (miRNAs) play vital roles in the regulation of plant development, but how they function in the sixth leaf at the six-leaf (V6) stage to influence jointing stage heterosis is still unclear. RESULT: Our objective was to study miRNAs in four hybrid combinations developed in accordance with the Reid × Tang-SPT pattern, Zhengdan 958, Anyu 5 (Ye 478 × Chang 7-2), Ye 478 × Huangzaosi, Zheng 58 × Huangzaosi, and their parental inbred lines to explore the mechanism related to heterosis. A total of 234 miRNAs were identified in the sixth leaf at the V6 stage, and 85 miRNAs were differentially expressed between the hybrid combinations and their parental inbred lines. Most of the differentially expressed miRNAs were non-additively expressed, which indicates that miRNAs may participate in heterosis at the jointing stage. miR164, miR1432 and miR528 families were repressed in the four hybrid combinations, and some miRNAs, such as miR156, miR399, and miR395 families, exhibited different expression trends in different hybrid combinations, which may result in varying effects on the heterosis regulatory mechanism. CONCLUSIONS: The potential targets of the identified miRNAs are related to photosynthesis, the response to plant hormones, and nutrient use. Different hybrid combinations employ different mature miRNAs of the same miRNA family and exhibit different expression trends that may result in enhanced or repressed gene expression to regulate heterosis. Taken together, our results reveal a miRNA-mediated network that plays a key role in jointing stage heterosis via posttranscriptional regulation.

ZmIBH1-1 regulates plant architecture in maize.

Leaf angle (LA) is a critical agronomic trait in maize, with more upright leaves allowing higher planting density, leading to more efficient light capture and higher yields. A few genes responsible for variation in LA have been identified by map-based cloning. In this study, we cloned maize ZmIBH1-1, which encodes a bHLH transcription factor with both a basic binding region and a helix-loop-helix domain, and the results of qRT-PCR showed that it is a negative regulator of LA. Histological analysis indicated that changes in LA were mainly caused by differential cell wall lignification and cell elongation in the ligular region. To determine the regulatory framework of ZmIBH1-1, we conducted RNA-seq and DNA affinity purification (DAP)-seq analyses. The combined results revealed 59 ZmIBH1-1-modulated target genes with annotations, and they were mainly related to the cell wall, cell development, and hormones. Based on the data, we propose a regulatory model for the control of plant architecture by ZmIBH1-1 in maize.

MicroRNA 399 as a potential integrator of photo-response, phosphate homeostasis, and sucrose signaling under long day condition.

BACKGROUND: Photoperiod-sensitivity is a critical endogenous regulatory mechanism for plant growth and development under specific environmental conditions, while phosphate and sucrose signaling processes play key roles in cell growth and organ initiation. MicroRNA399 is phosphate-responsive, but, whether it has roles in other metabolic processes remains unknown. RESULTS: MicroRNA399 was determined to be sucrose-responsive through a microRNA array assay. High levels of sucrose inhibited the accumulation of microRNA399 family under phosphate starvation conditions in Arabidopsis thaliana. Similarly, exogenous sucrose supplementation also reduced microRNA399 expression in maize at developmental transition stages. RNA sequencing of a near-isogenic line(photoperiod-sensitive) line and its recurrent parent Huangzao4, a photoperiod-insensitive line, was conducted at various developmental stages. Members of microRNA399 family were down-regulated under long-day conditions in the photoperiod-sensitive near-isogenic line that accumulated more sucrose in vivo compared with the control line Huangzao4. CONCLUSION: MicroRNA399s may play central roles in the integration of sucrose sensing and photoperiodic responses under long day conditions in maize.

Dual functions of ZmNF-YA3 in photoperiod-dependent flowering and abiotic stress responses in maize.

Nuclear factor-Y (NF-Y) transcription factors are important regulators of several essential biological processes, including embryogenesis, drought resistance, meristem maintenance, and photoperiod-dependent flowering in Arabidopsis. However, the regulatory mechanisms of NF-Ys in maize (Zea mays) are not well understood yet. In this study, we identified an NF-Y transcription factor, ZmNF-YA3. Genome-wide analysis showed that ZmNF-YA3 bound to >6000 sites in the maize genome, 2259 of which are associated with genic sequences. ZmNF-YA3 was found to interact with CONSTANS-like (CO-like) and flowering promoting factor1 (FPF1) through yeast two-hybrid and bimolecular fluorescence complementation (BiFC) assays. Quantitative real-time reverse transcription-PCR (qRT-PCR) combined with yeast one-hybrid assay and EMSA suggested that NF-YA3 could promote early flowering by binding to the FLOWERING LOCUS T-like12 (FT-like12) promoter in maize. Morerover, we also showed that ZmNF-YA3 could improve drought and high-temperature tolerance through binding to the promoter regions of bHLH92, FAMA, and the jasmonic acid activator MYC4, respectively. These results contribute to a comprehensive understanding of the molecular mechanisms and regulatory networks of NF-Y transcription factors in regulating maize flowering time and stress response in maize.

The STAT3 HIES mutation is a gain-of-function mutation that activates genes via AGG-element carrying promoters.

Cytokine or growth factor activated STAT3 undergoes multiple post-translational modifications, dimerization and translocation into nuclei, where it binds to serum-inducible element (SIE, 'TTC(N3)GAA')-bearing promoters to activate transcription. The STAT3 DNA binding domain (DBD, 320-494) mutation in hyper immunoglobulin E syndrome (HIES), called the HIES mutation (R382Q, R382W or V463Δ), which elevates IgE synthesis, inhibits SIE binding activity and sensitizes genes such as TNF-α for expression. However, the mechanism by which the HIES mutation sensitizes STAT3 in gene induction remains elusive. Here, we report that STAT3 binds directly to the AGG-element with the consensus sequence 'AGG(N3)AGG'. Surprisingly, the helical N-terminal region (1-355), rather than the canonical STAT3 DBD, is responsible for AGG-element binding. The HIES mutation markedly enhances STAT3 AGG-element binding and AGG-promoter activation activity. Thus, STAT3 is a dual specificity transcription factor that promotes gene expression not only via SIE- but also AGG-promoter activity.

Dual functions of the ZmCCT-associated quantitative trait locus in flowering and stress responses under long-day conditions.

BACKGROUND: Photoperiodism refers to the ability of plants to measure day length to determine the season. This ability enables plants to coordinate internal biological activities with external changes to ensure normal growth. However, the influence of the photoperiod on maize flowering and stress responses under long-day (LD) conditions has not been analyzed by comparative transcriptome sequencing. The ZmCCT gene was previously identified as a homolog of the rice photoperiod response regulator Ghd7, and associated with the major quantitative trait locus (QTL) responsible for Gibberella stalk rot resistance in maize. However, its regulatory mechanism has not been characterized. RESULTS: We mapped the ZmCCT-associated QTL (ZmCCT-AQ), which is approximately 130 kb long and regulates photoperiod responses and resistance to Gibberella stalk rot and drought in maize. To investigate the effects of ZmCCT-AQ under LD conditions, the transcriptomes of the photoperiod-insensitive inbred line Huangzao4 (HZ4) and its near-isogenic line (HZ4-NIL) containing ZmCCT-AQ were sequenced. A set of genes identified by RNA-seq exhibited higher basal expression levels in HZ4-NIL than in HZ4. These genes were associated with responses to circadian rhythm changes and biotic and abiotic stresses. The differentially expressed genes in the introgressed regions of HZ4-NIL conferred higher drought and heat tolerance, and stronger disease resistance relative to HZ4. Co-expression analysis and the diurnal expression rhythms of genes related to stress responses suggested that ZmCCT and one of the circadian clock core genes, ZmCCA1, are important nodes linking the photoperiod to stress tolerance responses under LD conditions. CONCLUSION: Our study revealed that the photoperiod influences flowering and stress responses under LD conditions. Additionally, ZmCCT and ZmCCA1 are important functional links between the circadian clock and stress tolerance. The establishment of this particular molecular link has uncovered a new relationship between plant photoperiodism and stress responses.

Is Smoking Associated with the Risk of Acute Mountain Sickness? A Systematic Review and Meta-Analysis.

Background: Controversy remains in the association between smoking and the risk of acute mountain sickness (AMS). Therefore, a systematic review of the existing literature may help clarify this association. Methods: We conducted a systematic search of PubMed, Embase, and Cochrane Library from database inception up to October 19, 2021. Both unadjusted and adjusted relative risks (RRs) and 95% confidence intervals (CIs) were calculated to compare the risk of AMS in the smoking and nonsmoking groups. Meta-regression was conducted to explore the factors causing heterogeneity of the studies, and subsequent stratified analysis was performed to present the pooled RR in different subgroups. Publication bias was assessed using funnel plots. Results: A total of 28 eligible articles (31 studies) were included. The pooled unadjusted and adjusted RRs were 0.88 (95% CI: 0.78-1.01) and 0.87 (95% CI: 0.77-0.99), respectively, using random-effect models. Publication bias was observed owing to restrictions on the sample size. The ascending altitude and sex composition of the study population were likely sources of heterogeneity according to meta-regression. Studies on participants with an ascending altitude of over 3,500 m or composed of both males and females reported a slight but not significant protective effect of smoking on the risk of AMS, with high heterogeneity. Conclusions: Smoking had no significant effect on AMS risk in this meta-analysis. Current studies showed high heterogeneity and included little information on quantitative exposure to smoking (i.e., dose and frequency); thus, the results require careful explanation.

Oxytocin alleviates liver fibrosis via hepatic macrophages.

Background & Aims: Previous studies demonstrated oxytocin treatment effectiveness in reducing mortality and reversing liver fibrosis in mice. However, the underlying mechanism remains obscure, given the absence of oxytocin receptor expression in hepatic stellate cells, the primary liver fibrosis effector cells. Methods: A comprehensive map of cell populations in fibrotic liver was generated using single-cell sequencing. The map enabled our study of the target cells of oxytocin action in the liver in more dimensions. Furthermore, we elucidated the mechanism of the oxytocin signaling system in hepatic macrophages using oxytocin receptor-specific knockout mice and liver fibrosis animal models. Results: The carbon tetrachloride-induced hepatic fibrosis and bile duct ligation hepatic fibrosis mouse models demonstrated that oxytocin reversed hepatic fibrosis in mice. The mapped liver cell populations demonstrated that oxytocin promoted the phenotypic switch from Ly6high to Ly6Clow in myeloid-derived macrophages. The phenotypic control of oxytocin signaling system activation on this phenotypic switch was validated using myeloid-specific oxytocin receptor knockout mice. Subsequent studies demonstrated that the calcium inward flow induced by oxytocin receptor activation activated the key orphan nuclear receptor NR4A1, which controls macrophage phenotypic switching. Specifically, calcium ions activated CREB, a key target regulator of NR4A1 expression. Conclusions: The findings established hepatic macrophages as a hub responsible for the oxytocin-mediated alleviation of liver fibrosis. This study revealed a novel pathway where oxytocin regulates macrophage phenotype. Impact and implications: Previous studies revealed for the first time the expression of oxytocin receptors in the liver. The present study shows that oxytocin reverses hepatic fibrosis and that hepatic macrophages are the central hub of oxytocin-mediated alleviation of hepatic fibrosis by promoting a phenotypic switch in hepatic macrophages, transitioning from Ly6high to Ly6Clow expression. The present study reveals a novel pathway by which oxytocin regulates macrophage phenotype. In addition, the potential applications of oxytocin and its analogues, as traditional drugs for clinical application, in the treatment of liver fibrosis deserve to be further explored.

Food processing industry changes across China regions: The case of flour, rice, oil, and other cereal derivative food.

Faced with the pressure of slowing industrial growth and industrial transformation requirements, it is crucial to analyze the changes and the corresponding driving factors of the food processing industry in China. An analysis using traditional and spatial shift-share models was conducted to decompose the changes in the food processing industry in each region of China from 2009 to 2019 into five effects: national growth effect (NG), industrial mix effect (IM), competitive effect (CE), neighbor-nation competitive effect (NNC), and region-neighbor competitive effect (RNC). Among the five effects from 2009 to 2019, the NG contributed the most to the growth in most regions, indicating that the development of the food processing industry in China was greatly influenced by the industrial base and that China's food processing industry has entered a "growth bottleneck period." During the period 2009-2014 to period 2014-2019, compared to the IM and CE, the influence of spatial spillover effects was stronger and significantly enhanced. Moreover, the IM, CE, NNC, and RNC in most southern regions were stronger than those in most northern regions. Therefore, China's food processing industry needs and is transforming into high-quality development. It is necessary to innovate the mode of development of food processing industry and strengthen interregional exchanges and cooperation.

Graphdiyne oxide elicits a minor foreign-body response and generates quantum dots due to fast degradation.

Graphdiyne (GDY) is a novel two-dimensional (2D) carbon allotrope that has attracted much attention in materials, physics, chemistry, and microelectronics for its excellent properties. Much effort has been devoted to exploring the biomedical applications of GDY in 2D carbon nanomaterials, especially for smart drugs and gene delivery. However, few studies have focused on the biocompatibility and potential environmental hazards of GDY and its derivatives. In this study, graphdiyne oxide (GDYO) and graphene oxide (GO) were obtained using different oxidation methods. Their cytotoxicity and hemolysis in vitro and biocompatibility in subcutaneous and peritoneal locations in vivo were compared. GDYO had very low biotoxicity in vitro and was moderately biocompatible in the muscle and abdominal cavity in vivo. Highly oxidized products and graphdiyne quantum dots (GDQDs) were observed in peritoneal cells. GDYO had better biocompatibility and its sheet size was easily diminished through oxidative degradation. Therefore, GDYO is a good candidate for use in 2D carbon nanomaterials in biomedicine.

Degradation behavior of 2D auxetic structure with biodegradable polymer under mechanical stress.

Coronary heart disease is serious harm to human health. Vascular scaffold implantation is the main treatment. Biodegradable polymers are widely used in vascular scaffolds for good biodegradability and biocompatibility. However, whether the mechanical properties and radial expansion ability can successfully implant the scaffold without acute elastic retraction remains to be further studied. Because of the unique deformation mechanism, shear resistance, and resilience, auxetic structures can effectively avoid the restenosis of degraded vascular scaffolds. Firstly, the plane isotropic and plane anisotropic auxetic structural scaffolds were designed. The control structures (traditional structures) scaffolds were taken as the contrast. PCL was used to prepare the vascular auxetic by 3D printing. The printing parameters of fused deposition 3D printing, such as printing temperature, printing speed, and printing pressure, were studied to determine the optimal printing parameters of PCL. A self-assembled cyclic tensile stress loading device was used to investigate the degradation behavior of different scaffolds under different sizes of cyclic tensile stress, such as surface morphology, pH changes, mass loss rate, and mechanical properties. The increase of stress, surface roughness, and mass loss rate of the scaffolds all showed an increasing trend. pH gradually decreased from the fifth week, and the decrease was proportional to the stress. A large level of stress loading intensifies the decline of elastic modulus and the ultimate strength of the scaffold. In conclusion, the increase of periodic tensile stress will accelerate the degradation of scaffolds, and the degradation behavior of scaffolds with different configurations is different. The degradation rate of dilatant scaffolds was higher than that of control scaffolds, and the degradation rate of anisotropic auxetic scaffolds was higher than that of isotropic auxetic scaffolds, which provides a theoretical reference for the application of auxetic structure in the degradation of vascular scaffolds.

Molecular mechanism analysis of ZmRL6 positively regulating drought stress tolerance in maize.

MYB-related genes, a subclass of MYB transcription factor family, have been documented to play important roles in biological processes such as secondary metabolism and stress responses that affect plant growth and development. However, the regulatory roles of MYB-related genes in drought stress response remain unclear in maize. In this study, we discovered that a 1R-MYB gene, ZmRL6, encodes a 96-amino acid protein and is highly drought-inducible. We also found that it is conserved in both barley (Hordeum vulgare L.) and Aegilops tauschii. Furthermore, we observed that overexpression of ZmRL6 can enhance drought tolerance while knock-out of ZmRL6 by CRISPR-Cas9 results in drought hypersensitivity. DAP-seq analyses additionally revealed the ZmRL6 target genes mainly contain ACCGTT, TTACCAAAC and AGCCCGAG motifs in their promoters. By combining RNA-seq and DAP-seq results together, we subsequently identified eight novel target genes of ZmRL6 that are involved in maize's hormone signal transduction, sugar metabolism, lignin synthesis, and redox signaling/oxidative stress. Collectively, our data provided insights into the roles of ZmRL6 in maize's drought response.