Auxin regulates anthocyanin biosynthesis through the Aux/IAA–ARF signaling pathway in apple

Auxin signaling,which is crucial for normal plant growth and development,mainly depends on ARF–Aux/IAA interactions.However,little is known regarding the regulatory effects of auxin signaling on anthocyanin metabolism in apple(Malus domestica).We investigated the functions of MdARF13,which contains a repression domain and is localized to the nucleus.This protein was observed to interact with the Aux/IAA repressor,MdIAA121,through its C-terminal dimerization domain.Protein degradation experiments proved that MdIAA121 is an unstable protein that is degraded by the 26S proteasome.Additionally,MdIAA121 stability is affected by the application of exogenous auxin.Furthermore,the overexpression of MdIAA121 and MdARF13 in transgenic red-fleshed apple calli weakened the inhibitory effect of MdARF13 on anthocyanin biosynthesis.These results indicate that the degradation of MdIAA121 induced by auxin treatment can release MdARF13,which acts as a negative regulator of the anthocyanin metabolic pathway.Additionally,yeast two-hybrid,bimolecular fluorescence complementation,and pull-down assays confirmed that MdMYB10 interacts with MdARF13.A subsequent electrophoretic mobility shift assay and yeast one-hybrid assay demonstrated that MdARF13 directly binds to the promoter of MdDFR,which is an anthocyanin pathway structural gene.Interestingly,chromatin immunoprecipitation–quantitative real-time PCR results indicated that the overexpression of MdIAA121 clearly inhibits the recruitment of MdARF13 to the MdDFR promoter.Our findings further characterized the mechanism underlying the regulation of anthocyanin biosynthesis via Aux/IAA–ARF signaling.

Design of sextuple-mode triple-ring HTS UWB filter using two-round interpolation

A single-stage ring resonator capable of introducing six modes within the ultra-wideband(UWB)passband is presented.The sextuple-mode resonator consists of three rings and three sets of stepped-impedance open stubs.Based on this sextuple-mode resonator,a UWB filter fed by the interdigital-coupling line(ICL)is designed.And we propose a two-round interpolation method to obtain the filter's initial dimensions.The designed filter is fabricated on a double-sided YBCO/MgO/YBCO high-temperature superconducting(HTS)thin film for demonstration.The experimental results show that this UWB filter produces eight resonances in the passband eventually,which effectively improves the in-band reflection and the band-edge steepness.Moreover,the upper stopband performance is enhanced due to the transmission zeros(TZs)generated by the stepped-impedance open stubs and the ICL structure.The measured good performance verifies the practicability of the two-round interpolation approach,which can also be extended to other odd-even-mode filter designs.

Switchable and tunable triple-channel bandpass filter

A triple-channel bandpass filter with switchable and tunable functions is proposed,which is based on a triple-mode cross resonator.The varactors and switching diodes are loaded at the end of the resonator.Because of the use of switches,resonators have four working states:conventional single-mode,two dual-modes,and one triple-mode.The varactor makes the channel independently adjustable.Finally,a triple-channel bandpass filter with switchable and tunable functions is designed by using two identical triple-mode resonator coupling structures.To solve the problem of whether each channel in the multi-channel filter is independently adjustable,this paper gives a simple and rigorous judgment method,namely rank criterion,which is a necessary and sufficient condition for each channel to be independently adjustable.The method of designing an element variable coupling matrix(EVCM)is adopted,which can not only obtain the desired frequency response through adjustable elements but also help to select resonators and coupling modes in the actual circuit design.The final circuit size of the designed filter is 0.29λg×0.26λg.The measured results are in good agreement with the simulation results.