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Summary: Flower color, which is determined by various chemical pigments, is a vital trait for ornamental plants, in which anthocyanin is a major component. However, the epigenetic regulation of anthocyanin biosynthesis remains poorly understood.During chrysanthemum cultivation, we found a heterochromatic chrysanthemum accession (YP) whose progeny generated by asexual reproduction contained both yellow‐flowered (YP‐Y) and pink‐flowered (YP‐P) plants. In this study, we aimed to elucidate the epigenetic mechanisms of different flower colors in the YP plant progeny.Metabolome and transcriptome analyses revealed that the difference in flower color between YP‐Y and YP‐P was caused by expression variation of the anthocyanin biosynthesis gene CmMYB6. Bisulfite sequencing revealed that methylation at the CmMYB6 promoter, especially in the CHH context, was higher in YP‐Y than YP‐P. After demethylation of the CmMYB6 promoter using the dCas9‐TET1cd system, the flower color returned from yellow to pink.Furthermore, the methylation status of the CmMYB6 promoter was higher in YP‐Y over three consecutive generations, indicating that this methylation status was heritable mitotically. Finally, investigation of other chrysanthemum cultivars showed that the methylation of CmMYB6 decreased gradually with the increase in anthocyanin content. These results lay an epigenetic foundation for the improvement of flower color in horticultural plants. [ABSTRACT FROM AUTHOR]

Continued research in fields such as materials science and biomedicine requires the development of a super‐resolution imaging technique with a large field of view (FOV) and deep subwavelength resolution that is compatible with both fluorescent and nonfluorescent samples. Existing on‐chip super‐resolution methods exclusively focus on either fluorescent or nonfluorescent imaging, and, as such, there is an urgent requirement for a more general technique that is capable of both modes of imaging. In this study, to realize labeled and label‐free super‐resolution imaging on a single scalable photonic chip, a universal super‐resolution imaging method based on the tunable virtual‐wavevector spatial frequency shift (TVSFS) principle is introduced. Using this principle, imaging resolution can be improved more than threefold over the diffraction limit of a linear optical system. Here, diffractive units are fabricated on the chip's surface to provide wavevector‐variable evanescent wave illumination, enabling tunable spatial frequency shifts in the Fourier space. A large FOV and resolutions of λ/4.7 and λ/7.1 were achieved for label‐free and fluorescently labeled samples using a gallium phosphide (GaP) chip. With its large FOV, compatibility with different imaging modes, and monolithic integration, the proposed TVSFS chip may advance fields such as cell engineering, precision industry inspection, and chemical research. [ABSTRACT FROM AUTHOR]

The diffraction limit substantially impedes the resolution of the conventional optical microscope. Under traditional illumination, the high‐spatial‐frequency light corresponding to the subwavelength information of objects is located in the near‐field in the form of evanescent waves, and thus not detectable by conventional far‐field objectives. Recent advances in nanomaterials and metamaterials provide new approaches to break this limitation by utilizing large‐wavevector evanescent waves. Here, a comprehensive review of this emerging and fast‐growing field is presented. The current superresolution imaging techniques based on evanescent‐wave‐assisted spatial frequency modulation, including hyperlens, microsphere lens, and evanescent field‐illuminated spatial frequency shift microscopy, are illustrated. They are promising in investigating unobserved details and processes in fields such as medicine, biology, and material research. Some current challenges and future possibilities of these superresolution methods are also discussed. [ABSTRACT FROM AUTHOR]

Highlights from the article: Keywords: frequency shifting and stitching; polygon planar waveguides; polymer fluorescent films; super-resolution imaging In article number 1900126, Xu Liu, Qing Yang, and co-workers present a waveguide chip design that permits label-free superresolution imaging. Frequency shifting and stitching, polygon planar waveguides, polymer fluorescent films, super-resolution imaging.

Wide field‐of‐view (FOV), label‐free, super‐resolution imaging is demonstrated using a specially designed waveguide chip that can illuminate a sample with multicolor evanescent waves travelling along different directions. The method is enabled by a polymer fluorescent film that emits over a broad wavelength range. Its polygonal geometry ensures coverage over all illumination directions, enabling high‐fidelity image reconstruction while minimizing distortion and image blurring. By frequency shifting and iterative stitching of different spatial frequencies in Fourier space, the reconstruction of 2D samples is achieved without distortion over wide FOVs. The fabrication process is facile and compatible with conventional semiconductor‐fabrication methods. The super‐resolution chip (SRC) can thus be produced with high yield, offering opportunities for potential conjunction of super‐resolution techniques integrated optical circuits or for the development of single‐use diagnostic kits. [ABSTRACT FROM AUTHOR]