The Tartary buckwheat bHLH gene ALCATRAZ contributes to silique dehiscence in Arabidopsis thaliana.

Tartary buckwheat is popular because of its rich nutrients. However, the difficulty in shelling restricts food production. The gene ALCATRAZ (AtALC) plays a key role in silique dehiscence in Arabidopsis thaliana. In this study, an atalc mutant was obtained by CRISPR/Cas9, and a FtALC gene homologous to AtALC was complemented into the atalc mutant to verify its function. Phenotypic observations showed that three atalc mutant lines did not dehiscence, while ComFtALC lines recovered the dehiscence phenotype. The contents of lignin, cellulose, hemicellulose, and pectin in the siliques of all the atalc mutant lines were significantly higher than those in the wild-type and ComFtALC lines. Moreover, FtALC was found to regulate the expression of cell wall pathway genes. Finally, the interaction of FtALC with FtSHP and FtIND was verified by yeast two-hybrid, bimolecular fluorescent complimentary (BIFC) and firefly luciferase completion imaging assays (LCIs). Our findings enrich the silique regulatory network and lay the foundation for the cultivation of easily shelled tartary buckwheat varieties.

On-Surface Self-Assembled Structural Transformation Induced by Schiff Base Reaction and Hydrogen bonds.

By utilizing scanning tunneling microscopy (STM), the self-assembled nanostructures of three characteristic aldehydes have been examined at the solution-solid interface. By introducing the active reactant 5-aminoisophthalic acid (5-AIPA), we succeeded in changing the self-assembled molecular structures through the condensation reaction and obtained the information on structural transformation in real time. The corresponding carboxyl conjugated derivatives were formed in situ and developed into the closely packed and ordered molecular architectures via hydrogen bonds at the solution-solid surface. The relevant simulations have been utilized to interpret the mechanisms of forming the nanostructures. The corresponding theoretical calculation is used to explain the reaction mechanism. Compared with the traditional ways, the on-surface condensation reaction in situ could not only provide a more convenient method for regulating the self-assembled architectures but also offer a promising strategy for building functional nanostructures and devices.

Solvent-Dependent Self-Assemblies and Pyridine Modulation of a Porphyrin Molecule at Liquid/Solid Interfaces.

On the highly oriented pyrolytic graphite (HOPG) surface, a new porphyrin molecule MT-4 containing a porphine core with six alkyl chains and two carboxyl groups has been explored using scanning tunneling microscopy (STM) technology. Solvent and pyridine regulation have been proved to be two effective ways to control and tune the supramolecular structure of MT-4 at interfaces. Different high-resolution STM (HR-STM) images with highly ordered and closely packed arrangements were gained at the corresponding liquid-solid interface, including phenyl octane (PO), 1-heptanoic acid (HA), and 1-hexanol. Except for the solvent effect, introducing pyridine derivatives such as 4,4'-vinylenedipyridine (DPE) and 4,4'-((1E,1'E)-(2,5-bis(octyloxy)-1,4-phenylene) bis(ethene-2,1-diyl)) dipyridine (PEBP-C8) is also effective to modulate the self-assembly of MT-4. With careful analysis of the STM pictures and the density functional theory (DFT) computational exploration, we figured out the molecular model, interaction energies, and self-assembly mechanism of each system at the interface. This work provides a simple and effective approach for quickly building diverse nanoarchitectures by utilizing different noncovalent interactions. Meanwhile, it would give a perspective to regulate and control self-assembly arrays for devising novel molecular-based materials through more optimal strategies.

Stabilization Effect of Amino Acid Side Chains in Peptide Assemblies on Graphite Studied by Scanning Tunneling Microscopy.

An analysis is presented of the effects of amino acid side chains on peptide assemblies in ambient conditions on a graphite surface. The molecularly resolved assemblies of binary peptides are examined with scanning tunneling microscopy. A comparative analysis of the assembly structures reveals that the lamellae width has an appreciable dependence on the peptide sequence, which could be considered as a manifestation of a stabilizing effect of side-chain moieties of amino acids with high (phenylalanine) and low (alanine, asparagine, histidine and aspartic acid) propensities for aggregation. These amino acids are representative for the chemical structures involving the side chains of charged (histidine and aspartic acid), aromatic (phenylalanine), hydrophobic (alanine), and hydrophilic (asparagine) amino acids. These results might provide useful insight for understanding the effects of sequence on the assembly of surface-bound peptides.

Self-Assembly and External Modulation of a Flexible Porphyrin Derivative on Highly Oriented Pyrolytic Graphite.

With the aid of scanning tunneling microscopy, we have examined the two-dimensional hydrogen-bonded networks of carboxyl-functionalized porphyrin derivative H2TCPp molecules at the heptanoic acid/HOPG interface. Moreover, we have successfully modulated the self-assembly structure of H2TCPp by introducing 1,2-di(4-pyridyl)ethylene molecules into the assembled system. By performing density functional theory calculations, we also revealed the formation mechanisms of the different assemblies and the modulation process. Comparing the self-assembly structures at the liquid/solid interface with those in bulk crystals, we have obtained deep insight into the differences in H2TCPp assemblies between 2D and 3D networks. Furthermore, this research is expected to deepen our understanding of on-surface phenomena and to provide a feasible process toward 2D assembly regulation.

Dual-affinity peptide mediated inter-protein recognition.

We present for the first time an enhanced interaction affinity between an abundant soluble protein (human serum albumin) and a membrane protein (chemokine receptor 4) mediated by a dual-affinity peptide E5.