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Phytohormones, epigenetic regulation and environmental factors regulate fruit ripening but their interplay during strawberry fruit ripening remains to be determined. In this study, bagged strawberry fruit exhibited delayed ripening compared with fruit grown in normal light, correlating with reduced abscisic acid (ABA) accumulation. Transcription of the key ABA catabolism gene, ABA 8′‐hydroxylase FaCYP707A4, was induced in bagged fruit. With light exclusion whole genome DNA methylation levels were up‐regulated, corresponding to a delayed ripening process, while DNA methylation levels in the promoter of FaCYP707A4 were suppressed, correlating with increases in transcript and decreased ABA content. Experiments indicated FaCRY1, a blue light receptor repressed in bagged fruit and FaAGO4, a key protein involved in RNA‐directed DNA methylation, could bind to the promoter of FaCYP707A4. The interaction between FaCRY1 and FaAGO4, and an increased enrichment of FaAGO4 directed to the FaCYP707A4 promoter in fruit grown under light suggests FaCRY1 may influence FaAGO4 to modulate the DNA methylation status of the FaCYP707A4 promoter. Furthermore, transient overexpression of FaCRY1, or an increase in FaCRY1 transcription by blue light treatment, increases the methylation level of the FaCYP707A4 promoter, while transient RNA interference of FaCRY1 displayed opposite phenotypes. These findings reveal a mechanism by which DNA methylation influences ABA catabolism, and participates in light‐mediated strawberry ripening. [ABSTRACT FROM AUTHOR]

The preparation of active packaging loaded with antimicrobial, antioxidant, and other functional agents has become a hot topic for food preservation in recent years. In this field, active fiber films based on spinning methods have attracted the interest of researchers owing to their high specific surface area, high porosity, high loading capacity, and good controlled release capacity. In the present work, neatly arranged ethyl cellulose (EC)/polyvinyl-pyrrolidone (PVP) fibrous films loaded with natamycin as an antimicrobial agent were prepared by microfluidic spinning. The encapsulation efficiency of natamycin was more than 90% in each group and the loading increased with increasing natamycin content. According to the characterization results of the natamycin-loaded EC/PVP fibrous films, hydrogen bonding was formed between natamycin and EC and PVP in the fibrous films. Meanwhile, the water contact angle of the fibrous films was increased, suggesting the improved hydrophobicity of the films. In the in vitro bacterial inhibition experiments, the active fiber films loaded with natamycin showed good antimicrobial activity, which could significantly inhibit the growth of gray mold. In conclusion, N-EC/PVP fibrous films with antimicrobial activity prepared by microfluidic spinning showed good potential in the field of active packaging. [ABSTRACT FROM AUTHOR]

SUMMARY: Flavonols are health‐promoting bioactive compounds important for human nutrition, health, and plant defense. The transcriptional regulation of kaempferol and quercetin biosynthesis has been studied extensively, while little is known about the regulatory mechanisms underlying myricetin biosynthesis, which has strong antioxidant, anticancer, antidiabetic, and anti‐inflammatory activities. In this study, the flavonol‐specific MrMYB12 in Morella rubra preferred activating the promoter of flavonol synthase 2 (MrFLS2) (6.4‐fold) rather than MrFLS1 (1.4‐fold) and upregulated quercetin biosynthesis. Furthermore, two SG44 R2R3‐MYB members, MrMYB5 and MrMYB5L, were identified by yeast one‐hybrid library screening using the promoter of flavonoid 3′,5′‐hydroxylase (MrF3′5′H), and transcript levels of these R2R3‐MYBs were correlated with accumulation of myricetin derivatives during leaf development. Dual‐luciferase and electrophoretic mobility shift assays demonstrated that both MrMYB5 and MrMYB5L could bind directly to MYB recognition sequence elements in promoters of MrF3′5′H or MrFLS1 and activate their expression. Protein–protein interactions of MrMYB5 or MrMYB5L with MrbHLH2 were confirmed by yeast two‐hybrid and bimolecular fluorescence complementation assays. MrMYB5L‐MrbHLH2 showed much higher synergistic activation of MrF3′5′H or MrFLS1 promoters than MrMYB5‐MrbHLH2. Studies with Arabidopsis thaliana homologs AtMYB5 and AtTT8 indicated that similar synergistic regulatory effects occur with promoters of MrF3′5′H or MrFLS1. Transient overexpression of MrMYB5L‐MrbHLH2 in Nicotiana benthamiana induced a higher accumulation of myricetin derivatives (57.70 μg g−1 FW) than MrMYB5‐MrbHLH2 (7.43 μg g−1 FW) when MrMYB12 was coexpressed with them. This study reveals a novel transcriptional mechanism regulating myricetin biosynthesis with the potential use for future metabolic engineering of health‐promoting flavonols. [ABSTRACT FROM AUTHOR]