Histone H2B.8 compacts flowering plant sperm through chromatin phase separation.

Sperm chromatin is typically transformed by protamines into a compact and transcriptionally inactive state1,2. Sperm cells of flowering plants lack protamines, yet they have small, transcriptionally active nuclei with chromatin condensed through an unknown mechanism3,4. Here we show that a histone variant, H2B.8, mediates sperm chromatin and nuclear condensation in Arabidopsis thaliana. Loss of H2B.8 causes enlarged sperm nuclei with dispersed chromatin, whereas ectopic expression in somatic cells produces smaller nuclei with aggregated chromatin. This result demonstrates that H2B.8 is sufficient for chromatin condensation. H2B.8 aggregates transcriptionally inactive AT-rich chromatin into phase-separated condensates, which facilitates nuclear compaction without reducing transcription. Reciprocal crosses show that mutation of h2b.8 reduces male transmission, which suggests that H2B.8-mediated sperm compaction is important for fertility. Altogether, our results reveal a new mechanism of nuclear compaction through global aggregation of unexpressed chromatin. We propose that H2B.8 is an evolutionary innovation of flowering plants that achieves nuclear condensation compatible with active transcription.

GRAS transcription factor PINNATE-LIKE PENTAFOLIATA2 controls compound leaf morphogenesis in Medicago truncatula.

The milestone of compound leaf development is the generation of separate leaflet primordia during the early stages, which involves two linked but distinct morphogenetic events: leaflet initiation and boundary establishment for leaflet separation. Although some progress in understanding the regulatory pathways for each event have been made, it is unclear how they are intrinsically coordinated. Here, we identify the PINNATE-LIKE PENTAFOLIATA2 (PINNA2) gene encoding a newly identified GRAS transcription factor in Medicago truncatula. PINNA2 transcripts are preferentially detected at organ boundaries. Its loss-of-function mutations convert trifoliate leaves into a pinnate pentafoliate pattern. PINNA2 directly binds to the promoter region of the LEAFY orthologue SINGLE LEAFLET1 (SGL1), which encodes a key positive regulator of leaflet initiation, and downregulates its expression. Further analysis revealed that PINNA2 synergizes with two other repressors of SGL1 expression, the BEL1-like homeodomain protein PINNA1 and the C2H2 zinc finger protein PALMATE-LIKE PENTAFOLIATA1 (PALM1), to precisely define the spatiotemporal expression of SGL1 in compound leaf primordia, thereby maintaining a proper pattern of leaflet initiation. Moreover, we showed that the enriched expression of PINNA2 at the leaflet-to-leaflet boundaries is positively regulated by the boundary-specific gene MtNAM, which is essential for leaflet boundary formation. Together, these results unveil a pivotal role of the boundary-expressed transcription factor PINNA2 in regulating leaflet initiation, providing molecular insights into the coordination of intricate developmental processes underlying compound leaf pattern formation.

COOLAIR and PRC2 function in parallel to silence FLC during vernalization.

Noncoding transcription induces chromatin changes that can mediate environmental responsiveness, but the causes and consequences of these mechanisms are still unclear. Here, we investigate how antisense transcription (termed COOLAIR) interfaces with Polycomb Repressive Complex 2 (PRC2) silencing during winter-induced epigenetic regulation of Arabidopsis FLOWERING LOCUS C (FLC). We use genetic and chromatin analyses on lines ineffective or hyperactive for the antisense pathway in combination with computational modeling to define the mechanisms underlying FLC repression. Our results show that FLC is silenced through pathways that function with different dynamics: a COOLAIR transcription-mediated pathway capable of fast response and in parallel a slow PRC2 switching mechanism that maintains each allele in an epigenetically silenced state. Components of both the COOLAIR and PRC2 pathways are regulated by a common transcriptional regulator (NTL8), which accumulates by reduced dilution due to slow growth at low temperature. The parallel activities of the regulatory steps, and their control by temperature-dependent growth dynamics, create a flexible system for registering widely fluctuating natural temperature conditions that change year on year, and yet ensure robust epigenetic silencing of FLC.

The MIO1-MtKIX8 module regulates the organ size in Medicago truncatula.

Plant organ size is an important agronomic trait tightly related to crop yield. However, the molecular mechanisms underlying organ size regulation remain largely unexplored in legumes. We previously characterized a key regulator F-box protein MINI ORGAN1 (MIO1)/SMALL LEAF AND BUSHY1 (SLB1), which controls plant organ size in the model legume Medicago truncatula. In order to further dissect the molecular mechanism, MIO1 was used as the bait to screen its interacting proteins from a yeast library. Subsequently, a KIX protein, designated MtKIX8, was identified from the candidate list. The interaction between MIO1 and MtKIX8 was confirmed further by Y2H, BiFC, split-luciferase complementation and pull-down assays. Phylogenetic analyses indicated that MtKIX8 is highly homologous to Arabidopsis KIX8, which negatively regulates organ size. Moreover, loss-of-function of MtKIX8 led to enlarged leaves and seeds, while ectopic expression of MtKIX8 in Arabidopsis resulted in decreased cotyledon area and seed weight. Quantitative reverse-transcription PCR and in situ hybridization showed that MtKIX8 is expressed in most developing organs. We also found that MtKIX8 serves as a crucial molecular adaptor, facilitating interactions with BIG SEEDS1 (BS1) and MtTOPLESS (MtTPL) proteins in M. truncatula. Overall, our results suggest that the MIO1-MtKIX8 module plays a significant and conserved role in the regulation of plant organ size. This module could be a good target for molecular breeding in legume crops and forages.

Fosaprepitant for postoperative nausea and vomiting in patients undergoing laparoscopic gastrointestinal surgery: a randomised trial.

BACKGROUND: Postoperative nausea and vomiting (PONV) is a major problem after surgery. Even with double prophylactic therapy including dexamethasone and a 5-hydroxytryptamine-3 receptor antagonist, the incidence is still high in many at-risk patients. Fosaprepitant, a neurokinin-1 receptor antagonist, is an effective antiemetic, but its efficacy and safety in combination antiemetic therapy for preventing PONV remain unclear. METHODS: In this randomised, controlled, double-blind trial, 1154 participants at high risk of PONV and undergoing laparoscopic gastrointestinal surgery were randomly assigned to either a fosaprepitant group (n=577) receiving fosaprepitant 150 mg i.v. dissolved in 0.9% saline 150 ml, or a placebo group (n=577) receiving 0.9% saline 150 ml before anaesthesia induction. Dexamethasone 5 mg i.v. and palonosetron 0.075 i.v. mg were each administered in both groups. The primary outcome was the incidence of PONV (defined as nausea, retching, or vomiting) during the first 24 postoperative hours. RESULTS: The incidence of PONV during the first 24 postoperative hours was lower in the fosaprepitant group (32.4% vs 48.7%; adjusted risk difference -16.9% [95% confidence interval: -22.4 to -11.4%]; adjusted risk ratio 0.65 [95% CI: 0.57 to 0.76]; P<0.001). There were no differences in severe adverse events between groups, but the incidence of intraoperative hypotension was higher (38.0% vs 31.7%, P=0.026) and intraoperative hypertension (40.6% vs 49.2%, P=0.003) was lower in the fosaprepitant group. CONCLUSIONS: Fosaprepitant added to dexamethasone and palonosetron reduced the incidence of PONV in patients at high risk of PONV undergoing laparoscopic gastrointestinal surgery. Notably, it increased the incidence of intraoperative hypotension. CLINICAL TRIAL REGISTRATION: NCT04853147.

Preoperative hs-CRP/HDL ratio is associated with increased risk for postoperative SIRS in elderly patients: a retrospective cohort study.

BACKGROUND: Systemic inflammatory response syndrome (SIRS) greatly affects postoperative lives of afflicted aged patients. This study aimed to determine whether preoperative high hs-CRP/HDL ratio (CHR) was associated with an increased risk of postoperative SIRS in the elderly population. METHODS: This retrospective cohort study included data on patients aged ≥ 65 years who underwent general anesthesia surgery at two clinical centers between January 2015 and September 2020. The primary exposure was preoperative CHR which was divided into two groups (≤ 12.82 and > 12.82) based on its normal range in our hospital, and the primary outcome was the incidence of postoperative SIRS. Targeted maximum likelihood estimation analyses were used to model the exposure-outcome relationship. RESULTS: The analysis included 5595 elderly patients, of whom 1410 (25.20%) developed SIRS within three postoperative days. Targeted maximum likelihood estimation analysis revealed that elderly patients with CHR > 12.82 vs. CHR ≤ 12.82 was associated with increased risk of postoperative SIRS (aOR = 1.40, 95% CI [1.33, 1.48], P < 0.001). Those results were consistent both in subgroup analyses and sensitivity analyses. Compared with patients with CHR ≤ 12.82, patients with CHR > 12.82 had a higher prevalence of postoperative SIRS (49.06% vs. 22.70%), postoperative in-hospital mortality (3.40% vs. 0.65%), a longer hospital stay after surgery [10 (IQR, 6-16) vs. 8 (IQR, 5-11) days] and higher direct medical cost [10070 (IQR, 6878-15577) vs. 7117 (IQR, 4079-10314) euros, all P < 0.001]. CONCLUSIONS: In elderly patients, preoperative CHR > 12.82 was significantly associated with a higher risk of postoperative SIRS.

Effects of Preoperative Oral Carbohydrate Electrolyte Drinks on Preoperative Hypokalemia Incidence in Patients Scheduled for Laparoscopic Colorectal Resection: A Three-Arm Randomized Clinical Trial.

PURPOSE: In our previous study, hypokalemia incidence was high in patients scheduled for laparoscopic colorectal resection. This trial was conducted to verify the effects of preoperative carbohydrate drinks containing potassium in these patients. DESIGN: A three-arm randomized controlled design was used. METHODS: Patients were randomly assigned to control, placebo, and treatment groups. In the control group, patients fasted from midnight. In the placebo group, patients fasted from midnight and received carbohydrate drinks 2 to 3 hours before surgery. In the treatment group, patients fasted from midnight and received carbohydrate drinks containing potassium supplementation 2 to 3 hours before surgery. The primary outcome was the incidence and severity of preoperative hypokalemia. Other outcomes included postoperative gastrointestinal function, including the time to postoperative first flatus (FFL) and first feces (FFE), and other complications. FINDINGS: The final analysis included 122 participants. The incidence of preoperative hypokalemia in the treatment group was significantly lower than that in the control and placebo groups (50% vs 88.1% vs 77.5%, P < .001). The severity of hypokalemia in the control and placebo groups was greater than that in the treatment group. No regurgitation or aspiration occurred in the three groups. No significant differences were observed among the three groups regarding time to FFL and FFE. CONCLUSIONS: Preoperative carbohydrate drinks containing potassium significantly reduced the incidence of preoperative hypokalemia and improved preoperative thirst and hunger, but did not reduce the postoperative time to FFL and FFE or length of hospital stay. However, as part of the enhanced recovery after surgery protocol, preoperative carbohydrate drinks containing potassium should be considered, as early as first admittance to hospital.

Perioperative administration of methylprednisolone was associated with postoperative pulmonary complications in elderly patients undergoing hip fracture surgery.

BACKGROUND: Postoperative pulmonary complications (PPCs) seriously affect the postoperative prognosis of elderly patients underwent hip fracture surgery. Although methylprednisolone is increasingly used, the association between perioperative methylprednisolone and PPCs is still controversial. The study aims to determine whether perioperative administration of methylprednisolone is associated with PPCs in elderly patients during hip fracture surgery. PATIENTS AND METHODS: In this retrospective cohort study, records of 584 patients (≥ 65 years) who underwent hip fracture surgery between January 2013 and October 2020 were extracted. Univariate and multivariate regression analysis were performed to identify the risk factors for PPCs. To further explore the association between administration of methylprednisolone and PPCs, 53 patients received methylprednisolone and 53 patients without methylprednisolone were matched for the confounding factors using propensity score matching (PSM) analysis. The odds ratios (OR) and 95% confidence intervals (CI) for the above variables were analyzed. RESULTS: The incidence of PPCs during postoperative hospitalization was 6.83% (38/556) among the elderly patients following hip fracture surgery. Patients with PPCs had higher postoperative mortality rate, longer hospital stay, more hospitalization cost, and higher incidence of cardiac arrest (all P < 0.05). Multivariate logistic regression analysis showed that age, hypertension, hypoglycemia, hypoproteinemia and perioperative methylprednisolone were independent risk factors for PPCs. Moreover, administration of methylprednisolone was significantly correlated with PPCs both before PSM adjustment (OR = 3.25; 95% CI, 1.67 to 6.33; P = 0.001) and after PSM adjustment (OR = 6.68; 95% CI, 1.40 to 31.82; P = 0.017). CONCLUSION: Perioperative administration of methylprednisolone is a risk factor for PPCs in elderly patients undergoing hip fracture surgery.

An explainable supervised machine learning predictor of acute kidney injury after adult deceased donor liver transplantation.

BACKGROUND: Early prediction of acute kidney injury (AKI) after liver transplantation (LT) facilitates timely recognition and intervention. We aimed to build a risk predictor of post-LT AKI via supervised machine learning and visualize the mechanism driving within to assist clinical decision-making. METHODS: Data of 894 cases that underwent liver transplantation from January 2015 to September 2019 were collected, covering demographics, donor characteristics, etiology, peri-operative laboratory results, co-morbidities and medications. The primary outcome was new-onset AKI after LT according to Kidney Disease Improving Global Outcomes guidelines. Predicting performance of five classifiers including logistic regression, support vector machine, random forest, gradient boosting machine (GBM) and adaptive boosting were respectively evaluated by the area under the receiver-operating characteristic curve (AUC), accuracy, F1-score, sensitivity and specificity. Model with the best performance was validated in an independent dataset involving 195 adult LT cases from October 2019 to March 2021. SHapley Additive exPlanations (SHAP) method was applied to evaluate feature importance and explain the predictions made by ML algorithms. RESULTS: 430 AKI cases (55.1%) were diagnosed out of 780 included cases. The GBM model achieved the highest AUC (0.76, CI 0.70 to 0.82), F1-score (0.73, CI 0.66 to 0.79) and sensitivity (0.74, CI 0.66 to 0.8) in the internal validation set, and a comparable AUC (0.75, CI 0.67 to 0.81) in the external validation set. High preoperative indirect bilirubin, low intraoperative urine output, long anesthesia time, low preoperative platelets, and graft steatosis graded NASH CRN 1 and above were revealed by SHAP method the top 5 important variables contributing to the diagnosis of post-LT AKI made by GBM model. CONCLUSIONS: Our GBM-based predictor of post-LT AKI provides a highly interoperable tool across institutions to assist decision-making after LT.

A Chromodomain-Helicase-DNA-Binding Factor Functions in Chromatin Modification and Gene Regulation.

Proteins in the Chromodomain-Helicase/ATPase-DNA-binding domain (CHD) family are divided into three groups. The function of group I CHD proteins in nucleosome positioning is well established, while that of group II members (represented by CHD3/Mi2) remains unclear. Using high-throughput approaches, we investigated the function of the group II rice (Oryza sativa) CHD protein CHR729 in nucleosome positioning, gene expression, histone methylation, and binding. Our data revealed that the chr729 mutation led to increased nucleosome occupancy in the rice genome and altered the expression and histone H3K4me3 modification of many, mainly underexpressed, genes. Further analysis showed that the mutation affected both the deposition and depletion of H3K4me3 in distinct chromatin regions, with concomitant changes in H3K27me3 modification. Genetic and genomic analyses revealed that CHR729 and JMJ703, an H3K4 demethylase, had agonistic, antagonistic, and independent functions in modulating H3K4me3 and the expression of subsets of genes. In addition, CHR729 binding was enriched in H3K4me3-marked genic and H3K27me3-marked intergenic regions. The results indicate that CHR729 has distinct functions in regulating H3K4me3 and H3K27me3 modifications and gene expression at different chromatin domains and provide insight into chromatin regulation of bivalent genes marked by both H3K4me3 and H3K27me3.

The WOX family transcriptional regulator SlLAM1 controls compound leaf and floral organ development in Solanum lycopersicum.

Plant-specific WOX family transcription factors play important roles ranging from embryogenesis to lateral organ development. The WOX1 transcription factors, which belong to the modern clade of the WOX family, are known to regulate outgrowth of the leaf blade specifically in the mediolateral axis; however, the role of WOX1 in compound leaf development remains unknown. Phylogenetic analysis of the whole WOX family in tomato (Solanum lycopersicum) indicates that there are 10 members that represent the modern, intermediate, and ancient clades. Using phylogenetic analysis and a reverse genetic approach, in this study we identified SlLAM1 in the modern clade and examined its function and tissue-specific expression pattern. We found that knocking out SlLAM1 via CRISPR/Cas9-mediated genome editing led to narrow leaves and a reduced number of secondary leaflets. Overexpression of tomato SlLAM1 could rescue the defects of the tobacco lam1 mutant. Anatomical and transcriptomic analyses demonstrated that floral organ development, fruit size, secondary leaflet initiation, and leaf complexity were altered due to loss-of-function of SlLAM1. These findings demonstrate that tomato SlLAM1 plays an important role in the regulation of secondary leaflet initiation, in addition to its conserved function in blade expansion.

The F-box protein MIO1/SLB1 regulates organ size and leaf movement in Medicago truncatula.

The size of leaf and seed organs, determined by the interplay of cell proliferation and expansion, is closely related to the final yield and quality of forage and crops. Yet the cellular and molecular mechanisms underlying organ size modulation remain poorly understood, especially in legumes. Here, MINI ORGAN1 (MIO1), which encodes an F-box protein SMALL LEAF AND BUSHY1 (SLB1) recently reported to control lateral branching in Medicago truncatula, was identified as a key regulator of organ size. We show that loss-of-function of MIO1/SLB1 severely reduced organ size. Conversely, plants overexpressing MIO1/SLB1 had enlarged organs. Cellular analysis revealed that MIO1/SLB1 controlled organ size mainly by modulating primary cell proliferation during the early stages of leaf development. Biochemical analysis revealed that MIO1/SLB1 could form part of SKP1/Cullin/F-box (SCF) E3 ubiquitin ligase complex, to target BIG SEEDS1 (BS1), a repressor of primary cell division, for degradation. Interestingly, we found that MIO1/SLB1 also played a key role in pulvinus development and leaf movement by modulating cell proliferation of the pulvinus as leaves developed. Our study not only demonstrates a conserved role of MIO1/SLB1 in the control of organ size in legumes, but also sheds light on the novel function of MIO1/SLB1 in leaf movement.

Development and performance assessment of novel machine learning models to predict pneumonia after liver transplantation.

BACKGROUND: Pneumonia is the most frequently encountered postoperative pulmonary complications (PPC) after orthotopic liver transplantation (OLT), which cause high morbidity and mortality rates. We aimed to develop a model to predict postoperative pneumonia in OLT patients using machine learning (ML) methods. METHODS: Data of 786 adult patients underwent OLT at the Third Affiliated Hospital of Sun Yat-sen University from January 2015 to September 2019 was retrospectively extracted from electronic medical records and randomly subdivided into a training set and a testing set. With the training set, six ML models including logistic regression (LR), support vector machine (SVM), random forest (RF), adaptive boosting (AdaBoost), extreme gradient boosting (XGBoost) and gradient boosting machine (GBM) were developed. These models were assessed by the area under curve (AUC) of receiver operating characteristic on the testing set. The related risk factors and outcomes of pneumonia were also probed based on the chosen model. RESULTS: 591 OLT patients were eventually included and 253 (42.81%) were diagnosed with postoperative pneumonia, which was associated with increased postoperative hospitalization and mortality (P < 0.05). Among the six ML models, XGBoost model performed best. The AUC of XGBoost model on the testing set was 0.734 (sensitivity: 52.6%; specificity: 77.5%). Pneumonia was notably associated with 14 items features: INR, HCT, PLT, ALB, ALT, FIB, WBC, PT, serum Na+, TBIL, anesthesia time, preoperative length of stay, total fluid transfusion and operation time. CONCLUSION: Our study firstly demonstrated that the XGBoost model with 14 common variables might predict postoperative pneumonia in OLT patients.

Analgesia and patient comfort after enhanced recovery after surgery in uvulopalatopharyngoplasty: a randomised controlled pilot study.

BACKGROUND: Uvulopalatopharyngoplasty(UPPP) is the most prevalent surgical treatment of obstructive sleep apnea, but postoperative pharyngeal pain may affect patient comfort. The enhanced recovery after surgery pathway has been proved beneficial to many types of surgery but not to UPPP yet. The aim of this pilot study was to preliminarily standrize an enhanced recovery after surgery protocol for UPPP, to assess whether it has positive effects on reducing postoperative pharyngeal pain and improving patient comfort, and to test its feasibility for an international multicentre study. METHODS: This randomised controlled study analysed 116 patients with obstructive sleep apnoea (OSA) who were undergoing UPPP in a single tertiary care hospital. They were randomly divided according to treatment: the ERAS group (those who received ERAS treatment) and the control group (those who received traditional treatment). Ninety-five patients completed the assessment (ERAS group, 59 patients; control group, 36 patients). Pharyngeal pain and patient comfort were evaluated using a visual analogue scale (VAS) at 30 min and at 6, 12, 24 and 48 h after UPPP. Complications, hospitalisation duration, and hospital cost were recorded. RESULTS: The VAS scores for resting pain and swallowing pain were significantly lower in the ERAS group than those in the control group at 30 min and at 6, 12, 24 and 48 h after surgery. Patient comfort was improved in the ERAS group. The hospitalisation duration and cost were comparable between the groups. The incidence of complications showed an increasing trend in the ERAS group. CONCLUSION: The ERAS protocol significantly relieved pharyngeal pain after UPPP and improved comfort in patients with OSA, which showed the prospect for an larger study. Meanwhile a potential increase of post-operative complications in the ERAS group should be noticed. TRIAL REGISTRATION: Chinese Clinical Trial Registry (23/09/2018, ChiCTR1800018537 ).

Ultrasound-guided transmuscular quadratus lumborum block reduced postoperative opioids consumptions in patients after laparoscopic hepatectomy: a three-arm randomized controlled trial.

BACKGROUND: To investigate whether transmuscular quadratus lumborum block (TQLB) combined with oxycodone-based patient-controlled intravenous analgesia (PCIA) compared with sufentanil-based patient-controlled intravenous analgesia could reduce postoperative pain and opioid consumption in patients undergoing laparoscopic hepatectomy. METHODS: Eighty patients undergoing laparoscopic hepatectomy surgery were randomly divided into Group S (Sufentanil for PCIA group), Group O (Oxycodone for PCIA group) and Group QO (transmuscular quadratus lumborum block + oxycodone for PCIA group). Primary outcome was Numerical Rating Scale (NRS) pain score when coughing at 6th hour after the operation. We summarized opioid consumption and recorded complications, opioid drug adverse reaction and analgesia satisfaction. RESULTS: NRS pain scores were significantly lower in Group QO while patients coughing at 6th hour after the operation compared with Group S and Group O (median (interquartile range [IQR]):Group S vs. Group O vs. Group QO 4.0 [3.0, 5.0] vs. 4.0[3.0,5.0]vs.3.0 [2.0, 3.0], p < 0.05). Within 24 h after surgery, the bolus times of PCIA (patient controlled intravenous analgesia) in the QO group was reduced which was compared with the Group S and Group O (median (interquartile range [IQR]):Group S vs. Group O vs. Group QO 13.0 [10.3, 19.5] vs. 11.5 [7.8, 18.3]vs.6.5[3.5,12.0], p < 0.05). The proportion of patients in the three groups who required additional analgesia was ranked as Group QO < Group O < Group S(p < 0.05). The analgesic satisfaction of patients in Group QO was higher than the Group S (p = 0.001) and Group O (p = 0.012). CONCLUSIONS: TQLB combined with oxycodone-based PCIA provided satisfactory postoperative analgesia and reduced oxycodone consumption in patients following laparoscopic hepatectomy. TRIAL REGISTRATION: ChiCTR1900028467 (22/12/2019).

Arabidopsis histone deacetylase HDA15 directly represses plant response to elevated ambient temperature.

Elevated ambient temperatures affect plant growth and substantially impact biomass and crop yield. Recent results have indicated that chromatin remodelling is critical in plant thermal responses but how histone modification dynamics affects plant thermal response has not been clearly demonstarted. Here we show that Arabidopsis histone deacetylase genes HDA9, HDA15 and HDA19 play distinct roles in plant response to elevated ambient temperature. hda9 and hda19 mutants showed a warm-temperature-insensitive phenotype at 27°C, whereas hda15 plants displayed a constitutive warm-temperature-induced phenotype at 20°C and an enhanced thermal response at 27°C. The hda19 mutation led to upregulation of genes mostly related to stress response at both 20 and 27°C. The hda15 mutation resulted in upregulation of many warm temperature-responsive as well as metabolic genes at 20 and 27°C, while hda9 led to differential expression of a large number of genes at 20°C and impaired induction of warm-temperature-responsive genes at 27°C. HDA15 is associated with thermosensory mark genes at 20°C and that the association is decreased after shifting to 27°C, indicating that HDA15 is a direct repressor of plant thermal-responsive genes at normal temperature. In addition, as hda9, the hda15 mutation also led to upregulation of many metabolic genes and accumulation of primary metabolites. Furthermore, we show that HDA15 interacts with the transcription factor HFR1 (long Hypocotyl in Far Red1) to cooperatively repress warm-temperature response. Our study demonstrates that the histone deacetylases target to different sets of genes and play distinct roles in plant response to elevated ambient temperature.

MERISTEM ACTIVITYLESS (MAL) is involved in root development through maintenance of meristem size in rice.

KEY MESSAGE: Rice MERISTEM ACTIVITYLESS (MAL), a RING-H2 finger domain (RFD)-containing gene, regulates meristem cell viability after the initiation of root primordia mediated by cytokinin signaling. Genes in the RING-H2 finger domain (RFD) family play various roles during plant development and in biotic/abiotic stress responses. Rice gene MERISTEM ACTIVITYLESS (MAL), being contained in the RING-H2 finger domain (RFD), is characterized by a transmembrane domain at the N-terminal and a C3H2C3 zinc finger domain at the C-terminal. To elucidate the physiological and molecular functions of MAL, we generated MAL knockdown transgenic plants by RNA interference. MAL RNA-interfered (MRi) transgenic plants exhibited a phenotype with shorter crown root length and lower crown root number, accompanied by a lower cell division rate. The low division rate was observed in the root meristem exactly where MAL was expressed. Furthermore, transcriptome data revealed that cell wall macromolecule metabolism-related genes and redox-related genes were enriched in MAL RNAi lines. Most of these differentially expressed genes (DEGs) were induced by exogenous cytokinin. Hence, we conclude that MAL, as a novel regulatory factor, plays a major role in maintaining cell viability in the meristem after the initiation of root primordial formation, mediated by cytokinin signaling and reactive oxygen species (ROS).

Correction to: Connexin32 plays a crucial role in ROS-mediated endoplasmic reticulum stress apoptosis signaling pathway in ischemia reperfusion-induced acute kidney injury.

An amendment to this paper has been published and can be accessed via the original article.

Lateral Leaflet Suppression 1 (LLS1), encoding the MtYUCCA1 protein, regulates lateral leaflet development in Medicago truncatula.

In species with compound leaves, the positions of leaflet primordium initiation are associated with local peaks of auxin accumulation. However, the role of auxin during the late developmental stages and outgrowth of compound leaves remains largely unknown. Using genome resequencing approaches, we identified insertion sites at four alleles of the LATERAL LEAFLET SUPPRESSION1 (LLS1) gene, encoding the auxin biosynthetic enzyme YUCCA1 in Medicago truncatula. Linkage analysis and complementation tests showed that the lls1 mutant phenotypes were caused by the Tnt1 insertions that disrupted the LLS1 gene. The transcripts of LLS1 can be detected in primordia at early stages of leaf initiation and later in the basal regions of leaflets, and finally in vein tissues at late leaf developmental stages. Vein numbers and auxin content are reduced in the lls1-1 mutant. Analysis of the lls1 sgl1 and lls1 palm1 double mutants revealed that SGL1 is epistatic to LLS1, and LLS1 works with PALM1 in an independent pathway to regulate the growth of lateral leaflets. Our work demonstrates that the YUCCA1/YUCCA4 subgroup plays very important roles in the outgrowth of lateral leaflets during compound leaf development of M. truncatula, in addition to leaf venation.

Dwarf and Increased Branching 1 controls plant height and axillary bud outgrowth in Medicago truncatula.

Optimizing plant architecture is an efficient approach for breeders to increase crop yields, and phytohormones such as gibberellins (GAs) play an important role in controlling growth. Medicago truncatula is a model legume species, but the molecular mechanisms underlying its architecture are largely unknown. In this study, we examined a tobacco retrotransposon Tnt1-tagged mutant collection of M. truncatula and identified dwarf and increased branching 1 (dib1), which exhibited extreme dwarfism and increased numbers of lateral branches. By analysis of the flanking sequences of Tnt1 insertions in different alleles of the tagged lines, we were able to clone DIB1. Linkage analysis and reverse screening of the flanking-sequence tags identified Medtr2g102570 as the gene corresponding to the DIB1 locus in the dib1 loss-of-function mutants. Phylogenetic analysis indicated that DIB1 was the ortholog of PsGA3ox1/Le in Pisum sativum. Expression analysis using a GUS-staining reporter line showed that DIB1 was expressed in the root apex, pods, and immature seeds. Endogenous GA4 concentrations were markedly decreased whilst some of representative GA biosynthetic enzymes were up-regulated in the dib1 mutant. In addition, exogenous application of GA3 rescued the dib1 mutant phenotypes. Overall, our results suggest that DIB1 controls plant height and axillary bud outgrowth via an influence on the biosynthesis of bioactive GAs. DIB1 could therefore be a good candidate gene for breeders to optimize plant architecture for crop improvement.