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Summary: Tree peony (Paeonia suffruticosa) undergoes bud endodormancy, and gibberellin (GA) pathway plays a crucial role in dormancy regulation. Recently, a key DELLA protein PsRGL1 has been identified as a negative regulator of bud dormancy release. However, the mechanism of GA signal to break bud dormancy remains unknown.In this study, yeast two‐hybrid screened PsSOC1 interacting with PsRGL1 through its MADS domain, and interaction was identified using pull‐down and luciferase complementation imaging assays Transformation in tree peony and hybrid poplar confirmed that PsSOC1 facilitated bud dormancy release. Transcriptome analysis of PsSOC1‐overexpressed buds indicated PsCYCD3.3 and PsEBB3 were its potential downstream targets combining with promoter survey, and they also accelerated bud dormancy release verified by genetic analysis.Yeast one‐hybrid, electrophoretic mobility shifts assays, chromatin immunoprecipitation quantitative PCR, and dual luciferase assays confirmed that PsSOC1 could directly bind to the CArG motif of PsCYCD3.3 and PsEBB3 promoters via its MADS domain. PsRGL1–PsSOC1 interaction inhibited the DNA‐binding activity of PsSOC1. Additionally, PsCYCD3.3 promoted bud dormancy release by rebooting cell proliferation.These findings elucidated a novel GA pathway, GA‐PsRGL1‐PsSOC1‐PsCYCDs, which expanded our understanding of the GA pathway in bud dormancy release. [ABSTRACT FROM AUTHOR]

Abstract Background Sufficient low temperature accumulation is the key strategy to break bud dormancy and promote subsequent flowering in tree peony anti-season culturing production. Exogenous gibberellins (GAs) could partially replace chilling to accelerate dormancy release, and different kinds of GAs showed inconsistent effects in various plants. To understand the effects of exogenous GA3 and GA4 on dormancy release and subsequent growth, the morphological changes were observed after exogenous GAs applications, the differentially expressed genes (DEGs) were identified, and the contents of endogenous phytohormones, starch and sugar were measured, respectively. Results Morphological observation and photosynthesis measurements indicated that both GA3 and GA4 applications accelerated bud dormancy release, but GA3 feeding induced faster bud burst, higher shoot and more flowers per plant. Full-length transcriptome of dormant bud was used as the reference genome. Totally 124 110 459, 124 015 148 and 126 239 836 reads by illumina transcriptome sequencing were obtained in mock, GA3 and GA4 groups, respectively. Compared with the mock, there were 879 DEGs and 2 595 DEGs in GA3 and GA4 group, 1 179 DEGs in GA3 vs GA4, and 849 DEGs were common in these comparison groups. The significant enrichment KEGG pathways of 849 DEGs highlighted plant hormone signal transduction, starch and sucrose metabolism, cell cycle, DNA replication, etc. Interestingly, the contents of endogenous GA1, GA3, GA4, GA7 and IAA significantly increased, ABA decreased after GA3 and GA4 treatments by LC–MS/MS. Additionally, the soluble glucose, fructose and trehalose increased after exogenous GAs applications. Compared to GA4 treatment, GA3 induced higher GA1, GA3 and IAA level, more starch degradation to generate more monosaccharide for use, and promoted cell cycle and photosynthesis. Higher expression levels of dormancy-related genes, TFL, FT, EBB1, EBB3 and CYCD, and lower of SVP by GA3 treatment implied more efficiency of GA3. Conclusions Exogenous GA3 and GA4 significantly accelerated bud dormancy release and subsequent growth by increasing the contents of endogenous bioactive GAs, IAA, and soluble glucose such as fructose and trehalose, and accelerated cell cycle process, accompanied by decreasing ABA contents. GA3 was superior to GA4 in tree peony forcing culture, which might because tree peony was more sensitive to GA3 than GA4, and GA3 had a more effective ability to induce cell division and starch hydrolysis. These results provided the value data for understanding the mechanism of dormancy release in tree peony.

Polyamide 6 (PA6) is a widely used thermoplastic engineering polymer, and the toughening modification for PA6 is always a main research topic. Meanwhile, the rigidity and heat resistance of PA6 usually deteriorate. To address this conflict, an epoxy compound (EGDE‐GA) was designed and synthesized and used to modify PA6 by dynamic vulcanization in twin‐screw extruder. EGDE‐GA is a linear molecule with a flexible molecular structure, which is favorable to toughening of PA6, and epoxy groups of EGDE‐GA can form local cross‐linked structure to improve the rigidity and retain the heat resistance of PA6. At the loading of 20 wt% of EGDE‐GA, the modified PA6 (PA6/EGDE‐GA 20) exhibited very high elongation at break and notched impact strength, which were increased by 413% and 520%, respectively, compared to those of PA6. The tensile strength was 61.4 MPa, which was higher than that of PA6. The heat deflection temperature remained almost unchanged. The results showed that the modified polymers may possess the high toughness without sacrificing the original rigidity by building the local crosslinked structure using dynamic vulcanization. The findings provide a feasible method for reusing and upcycling PA6 and other polymers with higher value and wider use in the industry. Highlights: The polyamide 6 (PA6) is toughened via dynamic vulcanization.The toughness of modified PA6 is increased by 520% compared with pure PA6.The toughened PA6 exhibits higher tensile strength than that of pure PA6.The toughened PA6 maintains its rigidity and heat resistance. [ABSTRACT FROM AUTHOR]

The chain extension of polyamide 6 (PA6) via a chemical reaction between a chain extender and the amino and carboxyl groups of the polymer increases the molecular weight and improves the mechanical properties, while typically deteriorates PA6 processability owing to cross‐linking. To resolve this issue, a dynamic covalent chain extender containing two anhydride groups is synthesized, which reacts only with amino groups, and employed to connect the PA6 molecular chains via the reaction between anhydride groups and terminal amino groups of PA6. On adding 3 wt% of the chain extender, the content of amino end groups is decreased from 30.6 to 5.8 μmol g−1 and the yield strength and elastic modulus of chain‐extended PA6 exceed those of original PA6 by 15.8% and 23.4%, respectively; meanwhile, the melt torque of chain‐extended PA6 is lower by 35.0% approximately, and the complex viscosity is also decreased. As far as we know, the dynamic covalent chain extender is used for the first time in the chain extension of PA6. This study provides a prospective approach to recycle PA6 for simultaneously improving mechanical properties and processability. [ABSTRACT FROM AUTHOR]