The TaWAK2-TaNAL1-TaDST pathway regulates leaf width via cytokinin signaling in wheat.

Leaves play a crucial role in photosynthesis and respiration, ultimately affecting the final grain yield of crops, including wheat (Triticum aestivum L.); however, the molecular mechanisms underlying wheat leaf development remain largely unknown. Here, we isolated a narrow-leaf gene, TaWAK2-A, through a map-based cloning strategy. TaWAK2-A encodes a wall-associated kinase (WAK), for which a single Ala-to-Val amino acid substitution reduces the protein stability, leading to a narrow-leaf phenotype in wheat. Further investigation suggests that TaWAK2 directly interacts with and phosphorylates TaNAL1, a trypsin-like serine/cysteine protease. The phosphorylated TaNAL1 is then involved in the degradation of the zinc finger transcription factor TaDST, which acts as a repressor of leaf expansion by activating the expression of the cytokinin oxidase gene TaCKX9 and triggering in vivo cytokinin degradation. Therefore, our findings elucidate a signaling cascade involving TaWAK2-TaNAL1-TaDST that sheds light on the regulation of wheat leaf development.

TaACTIN7-D regulates plant height and grain shape in bread wheat.

Exploitation of new gene resources and genetic networks contributing to the control of crop yield-related traits, such as plant height, grain size, and shape, may enable us to breed modern high-yielding wheat varieties through molecular methods. In this study, via ethylmethanesulfonate mutagenesis, we identify a wheat mutant plant, mu-597, that shows semi-dwarf plant architecture and round grain shape. Through bulked segregant RNA-seq and map-based cloning, the causal gene for the semi-dwarf phenotype of mu-597 is located. We find that a single-base mutation in the coding region of TaACTIN7-D (TaACT7-D), leading to a Gly-to-Ser (G65S) amino acid mutation at the 65th residue of the deduced TaACT7-D protein, can explain the semi-dwarfism and round grain shape of mu-597. Further evidence shows that the G65S mutation in TaACT7-D hinders the polymerization of actin from monomeric (G-actin) to filamentous (F-actin) status while attenuates wheat responses to multiple phytohormones, including brassinosteroids, auxin, and gibberellin. Together, these findings not only define a new semi-dwarfing gene resource that can be potentially used to design plant height and grain shape of bread wheat but also establish a direct link between actin structure modulation and phytohormone signal transduction.

FRIZZY PANICLE defines a regulatory hub for simultaneously controlling spikelet formation and awn elongation in bread wheat.

Grain yield in bread wheat (Triticum aestivum L.) is largely determined by inflorescence architecture. Zang734 is an endemic Tibetan wheat variety that exhibits a rare triple spikelet (TRS) phenotype with significantly increased spikelet/floret number per spike. However, the molecular basis underlying this specific spike morphology is completely unknown. Through map-based cloning, the causal genes for TRS trait in Zang734 were isolated. Furthermore, using CRISPR/Cas9-based gene mutation, transcriptome sequencing and protein-protein interaction, the downstream signalling networks related to spikelet formation and awn elongation were defined. Results showed that the null mutation in WFZP-A together with deletion of WFZP-D led to the TRS trait in Zang734. More interestingly, WFZP plays a dual role in simultaneously repressing spikelet formation gene TaBA1 and activating awn development genes, basically through the recruitments of chromatin remodelling elements and the Mediator complex. Our findings provide insights into the molecular bases by which WFZP suppresses spikelet formation but promotes awn elongation and, more importantly, define WFZP-D as a favourable gene for high-yield crop breeding.

Ultrasound-assisted closed reduction and percutaneous pinning for displaced and rotated lateral condylar humeral fractures in children.

BACKGROUND: It is difficult for surgeons to successfully perform closed reduction and percutaneous pinning on displaced and rotated lateral condylar humeral fractures in children. This study aimed to introduce an ultrasound-assisted closed reduction and percutaneous pinning technique and determine its usefulness in the treatment of displaced and rotated lateral condylar humeral fractures in children. METHODS: Between 2013 and 2018, 42 of 44 displaced and rotated pediatric lateral humeral condylar fractures were successfully treated with ultrasound-assisted closed reduction and percutaneous pinning. All surgical procedures were performed by 1 senior surgeon. Demographic and clinical data including age, sex, affected side, time from injury to reduction, operative time, and number of intraoperative radiographs (without fluoroscopy) were analyzed. Postoperative data were evaluated in terms of Kirschner wire in situ duration, follow-up duration, range of motion, carrying angle, cosmetic result, and complications. RESULTS: The average operative time was 67 minutes from 2013 to 2015 and 51 minutes from 2016 to 2018. All 42 patients who successfully underwent ultrasound-assisted closed reduction were followed up for >3 months, and 31 of 42 patients were followed up for >1 year. Among these 31 patients, the range-of-motion outcomes were excellent in 25 and good in 6. The carrying angle outcomes were excellent in 28 patients and good in 3. Two instances of wire infection, 9 instances of granulation tissue hyperplasia, and 23 instances of lateral spur formation occurred. No nonunion, avascular necrosis, or postoperative nerve issues were identified. CONCLUSIONS: The surgical technique of ultrasound-assisted closed reduction and percutaneous pinning presented in this study can effectively help surgeons reduce displaced and rotated lateral condylar humeral fractures in children to avoid some open reductions and achieve satisfactory outcomes.

Determining the stability of minimally displaced lateral humeral condyle fractures in children: ultrasound is better than arthrography.

BACKGROUND: Evaluating of the articular cartilage status of the distal humeral epiphysis is difficult. Ultrasound imaging of the elbow is increasingly being used to confirm the integrity of the articular cartilage of minimally displaced lateral humeral condyle fractures in children with minimally displaced fractures. The aims of this study were to assess the correlations between ultrasound and arthrography findings for predicting the integrity of the cartilage hinge and to describe the utility of ultrasound in determining the need for pre-treatment. METHODS: Thirty-nine patients with minimally displaced lateral humeral condyle fractures who underwent ultrasound and arthrography examinations before surgery from May 2018 to December 2019 were included in this study. Ultrasound and arthrography predictors of the cartilage hinge status were independently measured. The ultrasound and arthrography results were compared. RESULTS: The mean displacement of the fractures was 3.1 mm (range, 2.0~5.0 mm). Arthrography showed incomplete fractures in 24 patients (61.5%) and complete fractures in 15 patients (38.5%). Ultrasound showed incomplete fractures in 25 patients (64.1%) and complete fractures in 14 patients (35.9%). The ultrasound and arthrography results of the integrity of the articular surface were consistent in 92.3% of the cases, including 23 that were predicted to have an intact articular surface and 13 that were predicted to have an incongruity articular surface. There was no correlation between the displacement and the fracture appearing complete on the ultrasound scan. The Pearson coefficient between ultrasound and arthrography for assessing the integrity of the articular surface was 0.837. CONCLUSIONS: Ultrasound and arthrography assessments of the integrity of the cartilage hinge status appear to be highly consistent. Ultrasound can be used as a complementary tool with arthrography to predict the integrity of the cartilage hinge status in children with minimally displaced lateral humeral condyle fractures. LEVEL OF EVIDENCE: Prospective study; level II.

The routine cutoff displacement of 2 mm may not reliably reflect the stability of paediatric lateral humeral condyle fractures.

INTRODUCTION: Lateral humeral condyle fracture is one of the most common fractures in children. However, the prediction of the stability of the fracture with a cutoff displacement of 2 mm remains controversial. The aim of this study was to evaluate the reliability of the routine cutoff displacement of 2 mm in predicting the stability of paediatric lateral humeral condyle fractures. METHODS: A cohort of 79 children with imaging results for lateral humeral condyle fractures from 2013 to 2019 was evaluated. The displacement on the radiographs was measured by three surgeons at different levels, and ultrasound images were obtained by two senior surgeons. The interobserver and intraobserver reliability was assessed by the intraclass correlation coefficient (ICC). A binary logistic regression model and receiver operating characteristic (ROC) curves were used to evaluate the association between the measurement and the integrity of cartilage hinges. RESULTS: The ICC for the interobserver reliability was 0.85, and the intraobserver reliability was 0.93. For each additional millimetre of displacement, the odds of cartilage hinge disruption increased by 70%. The ROC curve determined that the Youden index was only 0.07 (sensitivity, 97.8%; specificity, 8.8%) with a cutoff displacement of 2 mm. CONCLUSIONS: The routine cutoff displacement of 2 mm may not reliably reflect the stability of paediatric lateral humeral condyle fractures. The cutoff value is sensitive but not specific for predicting whether the cartilage hinge is intact.

Impact of Transverse Ultrasound Images on the Classification and Treatment of Pediatric Lateral Humeral Condyle Fractures.

BACKGROUND: Pediatric lateral humeral condyle fractures (LHCFs) are sometimes misdiagnosed and inappropriately treated on the basis of x-ray radiographs because cartilage cannot be seen on radiographs. However, as a useful technique, transverse ultrasonography can accurately and readily determine the integrity of the cartilage hinge in pediatric LHCFs. The purpose of this study was to assess the reliability of the Jakob classification, the treatment plan, and the necessity for further examination of pediatric LHCFs with the use of x-ray with and without transverse ultrasound images. METHODS: Five pediatric orthopaedic surgeons with different levels of experience evaluated 62 cases on the basis of the use of x-ray alone and x-ray combined with transverse ultrasound images. These 2 types of evaluations were repeated after an interval of 4 to 6 weeks. At the time of each evaluation, all observers were asked to classify the fractures according to the Jakob classification, to formulate treatment plans, and to determine whether further examinations were required. RESULTS: After the training of transverse ultrasound image interpretation, the interobserver reliability of the Jakob classification significantly improved from fair (a kappa of 0.54) to moderate (a kappa of 0.71) with the addition of transverse ultrasound images. The treatment plan was changed from conservative treatment to surgical treatment in 7% of the ratings but from surgical treatment to conservative treatment in 15% of the ratings after reviewing the ultrasound images, and the difference was statistically significant (P=0.003). CONCLUSIONS: The use of the Jakob classification and a treatment plan for pediatric LHCFs can be optimized by the addition of transverse ultrasound images, especially after training for transverse ultrasound image interpretation. LEVEL OF EVIDENCE: Level III-diagnostic study.

A novel transverse ultrasonography technique for minimally displaced lateral humeral condyle fractures in children.

INTRODUCTION: Management of minimally displaced lateral humeral condyle fractures in pediatric patients is controversial. This is primarily because with current imaging modalities it is difficult to accurately and conveniently determine the stability of the fractures by detecting the integrity of the cartilage hinge. Nevertheless, transverse ultrasonography has not been intensively reported in previous studies. HYPOTHESIS: Transverse ultrasonography can determine the integrity of the cartilage hinge in minimally displaced lateral condyle fractures. MATERIALS AND METHODS: We retrospectively reviewed the medical records of 39 pediatric patients with minimally displaced fractures of the lateral humeral condyle who underwent transverse ultrasonography between 2014 and 2017. Conservative treatment was given to pediatric patients with intact cartilage hinges that had been confirmed by transverse ultrasound images. Surgical treatment was recommended for pediatric patients with disrupted cartilage hinges. Data regarding healing of the lateral humeral condyle fractures were recorded and analyzed. RESULTS: According to transverse ultrasonography, there were 14 children with intact cartilage hinges and 25 children with disrupted cartilage hinges. Fourteen children with intact cartilage hinges of the fracture were treated conservatively, and none of them showed secondary displacement. There were 16 children in whom there was surgical intervention, and 9 other children decided to have conservative treatment among the 25 children with disruption of the cartilage hinge. Five of these 9 children who underwent conservative treatment were found to have further displacement during an average of 12.6 days after the fracture event, and no other patient was found to have further displacement. CONCLUSION: Transverse ultrasonography can simply and accurately determine the stability of minimally displaced lateral condyle fractures without sedation, ionizing radiation or invasive techniques. We recommend routine use of transverse ultrasonography to detect stability of the fractures, which can effectively avoid inadequate treatment and unnecessary surgery in pediatric patients with minimally displaced fractures of the lateral humeral condyle. LEVEL OF EVIDENCE: IV, retrospective cohort study.