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Shoot branching affects plant architecture. In strawberry (Fragaria L.), short branches (crowns) develop from dormant axillary buds to form inflorescences and flowers. While this developmental transition contributes greatly to perenniality and yield in strawberry, its regulatory mechanism remains unclear and understudied. In the woodland strawberry (Fragaria vesca), we identified and characterized 2 independent mutants showing more crowns. Both mutant alleles reside in FveMYB117a, a R2R3-MYB transcription factor gene highly expressed in shoot apical meristems, axillary buds, and young leaves. Transcriptome analysis revealed that the expression of several cytokinin pathway genes was altered in the fvemyb117a mutant. Consistently, active cytokinins were significantly increased in the axillary buds of the fvemyb117a mutant. Exogenous application of cytokinin enhanced crown outgrowth in the wild type, whereas the cytokinin inhibitors suppressed crown outgrowth in the fvemyb117a mutant. FveMYB117a binds directly to the promoters of the cytokinin homeostasis genes FveIPT2 encoding an isopentenyltransferase and FveCKX1 encoding a cytokinin oxidase to regulate their expression. Conversely, the type-B Arabidopsis response regulators FveARR1 and FveARR2b can directly inhibit the expression of FveMYB117a, indicative of a negative feedback regulation. In conclusion, we identified FveMYB117a as a key repressor of crown outgrowth by inhibiting cytokinin accumulation and provide a mechanistic basis for bud fate transition in an herbaceous perennial plant. An MYB transcription factor directly regulates cytokinin homeostasis to repress axillary bud growth and consequently affect crown formation in woodland strawberry. [ABSTRACT FROM AUTHOR]

Congenital long QT syndrome is a type of inherited cardiovascular disorder characterized by prolonged QT interval. Patient often suffer from syncopal episodes, electrocardiographic abnormalities and life-threatening arrhythmia. Given the complexity of the root cause of the disease, a combination of clinical diagnosis and drug screening using patient-derived cardiomyocytes represents a more effective way to identify potential cures. We identified a long QT syndrome patient carrying a heterozygous KCNQ1 c.656G>A mutation and a heterozygous TRPM4 c.479C>T mutation. Implantation of implantable cardioverter defibrillator in combination with conventional medication demonstrated limited success in ameliorating long-QT-syndrome-related symptoms. Frequent defibrillator discharge also caused deterioration of patient quality of life. Aiming to identify better therapeutic agents and treatment strategy, we established a patient-specific iPSC line carrying the dual mutations and differentiated these patient-specific iPSCs into cardiomyocytes. We discovered that both verapamil and lidocaine substantially shortened the QT interval of the long QT syndrome patient-specific cardiomyocytes. Verapamil treatment was successful in reducing defibrillator discharge frequency of the KCNQ1/TRPM4 dual mutation patient. These results suggested that verapamil and lidocaine could be alternative therapeutic agents for long QT syndrome patients that do not respond well to conventional treatments. In conclusion, our approach indicated the usefulness of the in vitro disease model based on patient-specific iPSCs in identifying pharmacological mechanisms and drug screening. The long QT patient-specific iPSC line carrying KCNQ1/TRPM4 dual mutations also represents a tool for further understanding long QT syndrome pathogenesis. [ABSTRACT FROM AUTHOR]

The trithorax group (TrxG) factors play a critical role in the regulation of gene transcription by modulating histone methylation. However, the biological functions of the TrxG components are poorly characterized in different plant species. In this work, we identified three allelic ethyl methane-sulfonate-induced mutants P7, R67 and M3 in the woodland strawberry Fragaria vesca. These mutants show an increased number of floral organs, a lower pollination rate, raised achenes on the surface of the receptacle and increased leaf complexity. The causative gene is FvH4_6g44900, which contains severe mutations leading to premature stop codons or alternative splicing in each mutant. This gene encodes a protein with high similarity to ULTRAPETALA1, a component of the TrxG complex, and is therefore named as FveULT1. Yeast-two-hybrid and split-luciferase assays revealed that FveULT1 can physically interact with the TrxG factor FveATX1 and the PcG repressive complex 2 (PRC2) accessory protein FveEMF1. Transcriptome analysis revealed that several MADS-box genes, FveLFY and FveUFO were significantly up-regulated in fveult1 flower buds. The leaf development genes FveKNOXs , FveLFYa and SIMPLE LEAF1 were strongly induced in fveult1 leaves, and their promoter regions showed increased H3K4me3 levels and decreased H3K27me3 levels in fveult1 compared to WT. Taken together, our results demonstrate that FveULT1 is important for flower, fruit and leaf development and highlight the potential regulatory functions of histone methylation in strawberry. • Disruption of the trithorax group (TrxG) gene FveULT1 causes various defects in flowers, fruits, and leaves in woodland strawberry. • FveULT1 directly interacts with the TrxG component FveATX1 and the PcG protein FveEMF1. • Several MADS-box and class I KNOX transcription factors are negatively regulated by FveULT1 during flower development. • Disrupted FveULT1 causes altered H3K4me3 and H3K27me3 levels in the promoters of up-regulated genes in young leaves. [ABSTRACT FROM AUTHOR]

To assess pacing and electrophysiological parameters, as well as mid-term outcomes, among patients undergoing His bundle pacing (HBP) guided by KODEX-EPD (a novel mapping system). Consecutive patients undergoing conduction system pacing (CSP) for bradycardia indications were evaluated. Procedural and fluoroscopic times and pacing characteristics were compared between conventional fluoroscopy (the standard group, N = 20 cases) and KODEX-EPD mapping system guided group (the KODEX group, N = 20cases) at CSP implantation and all patients were followed at 6-month. HBP was achieved in all patients (the standard group 20/20 and the KODEX group 20/20). There was no difference in the mean procedure time between the two groups (63.7 ± 9.3 vs. 78.2 ± 25.1 min, p = 0.33). Compared with the standard group, the KODEX group significantly reduced the intraoperative X-ray exposure time (3.8 ± 0.5 vs. 19.3 ± 5.1 min, p < 0.05) and X-ray dose (23.6 ± 5.4 vs. 120.2 ± 38.3 mGy, p < 0.05). There were no significant differences in atrial impedance (643.0 ± 98.8 vs. 591.5 ± 92.1 Ω, p = 0.09), atrial sensing (2.9 ± 0.8 vs. 2.5 ± 0.8 mV, p = 0.08), ventricular sensing (12.8 ± 2.4 vs. 13.3 ± 3.3 mV, p = 0.63),atrial pacing threshold (1.0 ± 0.2 vs. 1.0 ± 0.1 V/0.4 ms, p = 0.81) and ventricular pacing threshold (1.0 ± 0.2 vs. 0.9 ± 0.1 V/0.4 ms, p = 0.63) between two groups, There were statistical differences in ventricular impedance (640.0 ± 80.3 vs. 702.0 ± 86.1 Ω, p < 0.05). There was no statistical significance in pacing parameters between the two groups at 6 months after procedure (p > 0.05). During the 6-months follow-up period, no adverse events occurred in the two groups. It can be concluded that KODEX-EPD can safely guide His bundle branch pacing lead implantation with reduced fluoroscopic time and dose without lengthening the procedure time. [ABSTRACT FROM AUTHOR]

The critical role of auxin in strawberry fruit set and receptacle enlargement was demonstrated previously. While fertilization is known to trigger auxin biosynthesis, the specific tissue source of fertilization-induced auxin is not well understood. Here, the auxin reporter DR5ver2::GUS was introduced into wild strawberry (Fragaria vesca) to reveal auxin distribution in the seed and fruit receptacle pre- and post-fertilization as well as in the root. In addition, the expression of TAR and YUCCA genes coding for enzymes catalysing the two-step auxin biosynthesis pathway was investigated using their respective promoters fused to the β-glucuronidase (GUS) reporter. Two FveTARs and four FveYUCs were shown to be expressed primarily in the endosperm and embryo inside the achenes as well as in root tips and lateral root primordia. Expression of these reporters in dissected tissues provided more detailed and precise spatial (cell and tissue) and temporal (pre- and post-fertilization) information on where auxin is synthesized and accumulates than previous studies in strawberry. Moreover, we generated CRISPR-mediated knock-out mutants of FveYUC10, the most abundant YUC in seeds; the mutants had a lower free auxin level in young fruit, but displayed no obvious morphological phenotypes. However, overexpression of FveYUC10 resulted in elongated hypocotyls in Arabidopsis caused by elevated auxin level. Overall, the study revealed auxin accumulation in the chalazal seed coat, embryo, receptacle vasculature, root tip, and lateral root primordia and highlighted the endosperm as the main auxin biosynthesis site for fruit set. [ABSTRACT FROM AUTHOR]