Flag leaf angle impacts the photosynthetic capacity of densely grown plants and is thus an important agronomic breeding trait for crop architecture and yield. The hormone auxin plays a key role in regulating this trait, yet the underlying molecular and cellular mechanisms remain unclear. Here, we report that two rice (Oryza sativa) auxin response factors (ARFs), OsARF6 and OsARF17, which are highly expressed in lamina joint tissues, control flag leaf angle in response to auxin. Loss-of-function double osarf6 osarf17 mutants displayed reduced secondary cell wall levels of lamina joint sclerenchymatous cells (Sc), resulting in an exaggerated flag leaf angle and decreased grain yield under dense planting conditions. Mechanical measurements indicated that the mutant lamina joint tissues were too weak to support the weight of the flag leaf blade, resembling the phenotype of the rice increased leaf angle1 (ila1) mutant. We demonstrate that OsARF6 and OsARF17 directly bind to the ILA1 promoter independently and synergistically to activate its expression. In addition, auxin-induced ILA1 expression was dependent on OsARF6 and OsARF17. Collectively, our study reveals a mechanism that integrates auxin signaling with secondary cell wall composition to determine flag leaf angle, providing breeding targets in rice, and potentially other cereals, for this key trait.
Lattice metamaterials constructed by curved microstructures exhibit large stretchability and are promising in soft electronics and soft robotics. Fractal structures are particularly efficient in improving stretchability as it shows multiple‐order uncurling. However, the development of fractal metamaterials is hindered by hierarchical structures and large deformations. In this study, a design framework combining experiments, hierarchical theoretical models, and finite element simulations is developed to program the mechanical behaviors of fractal metamaterials. For 3D printing, a digital design tool is developed to visualize the structure and automatically generate the manufacturing representations. Results show that large stretchability (≈360%), bionic stress–strain curve matching, and imperfection insensitivity can be programmed by tuning the geometric parameters. An integrated device of an electromyogram sensor embedded in an imperfection‐insensitive fractal metamaterial that matches the J‐shaped stress–strain curve of human skin is demonstrated. Light‐emitting diode devices based on fractal metamaterial with shape reconfiguration are also presented. This st paves a new way to realize multifunctional soft devices using fractal metamaterials.
Development of highly
efficient catalysts to expedite the degradation
of organic dyes has been drawing great attention. The aggregation
of catalysts reduces the accessibility of catalytic centers for organic
dyes and therefore decreases their catalytic ability. Herein, we report
a facile method to prepare highly biocompatible and stable dendrimer-encapsulated
palladium nanoparticles (Pdn-G5MCI NPs),
which exhibit high catalytic efficiency for oxidation of morin. The
biocompatible dendrimers were prepared via surface modification of
G5 polyamidoamine (G5 PAMAM) dendrimers using maleic anhydride and l-cysteine. Then, they were incubated with disodium tetrachloropalladate,
followed by reduction using sodium borohydride to generate Pdn-G5MCI NPs. Transmission electron microscopy
results demonstrated that palladium nanoparticles (Pd NPs) inside
Pdn-G5MCI had small diameters (1.77–2.35
nm) and monodisperse states. Dynamic light scattering results confirmed
that Pdn-G5MCI NPs had good dispersion
and high stability in water. Furthermore, MTT results demonstrated
that Pdn-G5MCI NPs had high biocompatibility.
More importantly, Pdn-G5MCI NPs successfully
catalyzed the decomposition of H2O2 to the hydroxyl
radical (•OH), and the generated •OH quickly oxidized morin. This reaction kinetics followed pseudo-first-order
kinetics. Apparent rate constant (kapp) is an important criterion for evaluating the catalytic rate. The
concentrations of Pdn-G5MCI NPs and H2O2 were positively correlated with kapp, whereas the correlation between the concentration
of morin and kapp was negative. The prepared
Pdn-G5MCI NPs have great potential to
catalyze the degradation of organic dyes in bio-related systems in
the future.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.