The root stem cell niche, which is composed of four mitotically inactive quiescent center (QC) cells and the surrounding actively divided stem cells in Arabidopsis, is critical for growth and root development. Here, we demonstrate that the Arabidopsis prohibitin protein PHB3 is required for the maintenance of root stem cell niche identity by both inhibiting proliferative processes in the QC and stimulating cell division in the proximal meristem (PM). PHB3 coordinates cell division and differentiation in the root apical meristem by restricting the spatial expression of ethylene response factor (ERF) transcription factors 115, 114, and 109. ERF115, ERF114, and ERF109 mediate ROS signaling, in a PLT-independent manner, to control root stem cell niche maintenance and root growth through phytosulfokine (PSK) peptide hormones in Arabidopsis.

In plants, the patterning of stem cell-enriched meristems requires a graded auxin response maximum that emerges from the concerted action of polar auxin transport, auxin biosynthesis, auxin metabolism, and cellular auxin response machinery. However, mechanisms underlying this auxin response maximum-mediated root stem cell maintenance are not fully understood. Here, we present unexpected evidence that WUSCHEL-RELATED HOMEOBOX 5 (WOX5) transcription factor modulates expression of auxin biosynthetic genes in the quiescent center (QC) of the root and thus provides a robust mechanism for the maintenance of auxin response maximum in the root tip. This WOX5 action is balanced through the activity of indole-3-acetic acid 17 (IAA17) auxin response repressor. Our combined genetic, cell biology, and computational modeling studies revealed a previously uncharacterized feedback loop linking WOX5-mediated auxin production to IAA17-dependent repression of auxin responses. This WOX5-IAA17 feedback circuit further assures the maintenance of auxin response maximum in the root tip and thereby contributes to the maintenance of distal stem cell (DSC) populations. Our experimental studies and in silico computer simulations both demonstrate that the WOX5-IAA17 feedback circuit is essential for the maintenance of auxin gradient in the root tip and the auxin-mediated root DSC differentiation.

Hybrid systems of hydrogels and metals with tough bonding may find widespread applications. Here, a simple and universal method to obtain strong adhesion between hydrogels and diverse metal surfaces, such as titanium, steel, nickel, tantalum, argentum, and aluminum, with adhesion energy up to >1000 J m−2 is reported. To achieve such, the metal surfaces are instantly modified with a linker molecule via soaking, dip‐coating, or drop‐casting. The designed linker molecule has a carboxylic acid group to bind with a metal surface, and a methacrylic group to crosslink with a hydrogel, thus bridging the interface between them. In addition, by introducing a stimulus‐responsive disulfide bond into the linker molecule, the on‐demand debonding between toughly bonded hydrogel and metal surface, which is enabled by reductive cleavage of the disulfide chemical linkage, is also demonstrated. More interestingly, after the reductive debonding, the resulting metal surface with free thiol groups can be easily rebonded with a second hydrogel without any further surface modification. The strategy may provide unique opportunities in designing hybrid devices that are suitable for complex and dynamic environments.

Ultrathin membranes with potentially high permeability are urgently demanded in water purification. However, their facile, controllable fabrication remains a grand challenge. Herein, we demonstrate a metal-coordinated approach towards defect-free and robust membranes with sub-10 nm thickness. Phytic acid, a natural strong electron donor, is assembled with metal ion-based electron acceptors to fabricate metal-organophosphate membranes (MOPMs) in aqueous solution. Metal ions with higher binding energy or ionization potential such as Fe3+ and Zr4+ can generate defect-free structure while MOPM-Fe3+ with superhydrophilicity is preferred. The membrane thickness is minimized to 8 nm by varying the ligand concentration and the pore structure of MOPM-Fe3+ is regulated by varying the Fe3+ content. The membrane with optimized MOPM-Fe3+ composition exhibits prominent water permeance (109.8 L m−2 h−1 bar−1) with dye rejections above 95% and superior stability. This strong-coordination assembly may enlighten the development of ultrathin high-performance membranes.

Reactive oxygen species (ROS) are recognized as important regulators of cell division and differentiation. The Arabidopsis thaliana P-loop NTPase encoded by APP1 affects root stem cell niche identity through its control of local ROS homeostasis. The disruption of APP1 is accompanied by a reduction in ROS level, a rise in the rate of cell division in the quiescent center (QC) and the promotion of root distal stem cell (DSC) differentiation. Both the higher level of ROS induced in the app1 mutant by exposure to methyl viologen (MV), and treatment with hydrogen peroxide (H2O2) rescued the mutant phenotype, implying that both the increased rate of cell division in the QC and the enhancement in root DSC differentiation can be attributed to a low level of ROS. APP1 is expressed in the root apical meristem cell mitochondria, and its product is associated with ATP hydrolase activity. The key transcription factors, which are defining root distal stem niche, such as SCARECROW (SCR) and SHORT ROOT (SHR) are both significantly down-regulated at both the transcriptional and protein level in the app1 mutant, indicating that SHR and SCR are important downstream targets of APP1-regulated ROS signaling to control the identity of root QC and DSCs.

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One of the current challenges in burn wound care is the development of multifunctional dressings that can protect the wound from bacteria or organisms and promote skin regeneration and tissue reconstitution. To this end, we report the design and fabrication of a composite electrospun membrane, comprised of electrospun polylactide: poly(vinyl pyrrolidone)/polylactide:poly(ethylene glycol) (PLA:PVP/PLA:PEG) core/shell fibers loaded with bioactive agents, as a functionally integrated wound dressing for efficient burns treatment. Different mass ratios of PLA:PVP in the shell were screened to optimize mechanical, physicochemical, and biological properties, in addition to controlled release profiles of loaded antimicrobial peptides (AMPs) from the fibers for desirable antibacterial activity. Fibroblasts were shown to readily adhere and proliferate when cultured on the membrane, indicating good in vitro cytocompatibility. The introduction of PLA beads by electrospraying on one side of the membrane resulted in biomimetic micro-nanostructures similar to those of lotus leaves. This designer structure rendered the composite membranes with superhydrophobic property to inhibit the adhesion/spreading of exogenous bacteria and other microbes. The administration of the resulting composite fibrous membrane on burnt skin in an infected rat model led to faster healing than a conventional product (sterile silicone membrane) and control detailed herein. These composite fibrous membranes loaded with bioactive drugs provide an integrated strategy for promoting burn wound healing and skin regeneration.