Abstract Sweetpotato ( Ipomoea batatas (L.) Lam) is the world’s seventh most important food crop by production quantity. Cultivated sweetpotato is a hexaploid (2n = 6x = 90), and its genome (B1B1B2B2B2B2) is quite complex due to polyploidy, self-incompatibility, and high heterozygosity. Here we established a haploid-resolved and chromosome-scale de novo assembly of autohexaploid sweetpotato genome sequences. Before constructing the genome, we created chromosome-scale genome sequences in I. trifida using a highly homozygous accession, Mx23Hm, with PacBio RSII and Hi-C reads. Haploid-resolved genome assembly was performed for a sweetpotato cultivar, Xushu18 by hybrid assembly with Illumina paired-end (PE) and mate-pair (MP) reads, 10X genomics reads, and PacBio RSII reads. Then, 90 chromosome-scale pseudomolecules were generated by aligning the scaffolds onto a sweetpotato linkage map. De novo assemblies were also performed for chloroplast and mitochondrial genomes in I. trifida and sweetpotato. In total, 34,386 and 175,633 genes were identified on the assembled nucleic genomes of I. trifida and sweetpotato, respectively. Functional gene annotation and RNA-Seq analysis revealed locations of starch, anthocyanin, and carotenoid pathway genes on the sweetpotato genome. This is the first report of chromosome-scale de novo assembly of the sweetpotato genome. The results are expected to contribute to genomic and genetic analyses of sweetpotato.
As a key structural parameter, phase depicts the arrangement of atoms in materials. Normally, a nanomaterial exists in its thermodynamically stable crystal phase. With the development of nanotechnology, nanomaterials with unconventional crystal phases, which rarely exist in their bulk counterparts, or amorphous phase have been prepared using carefully controlled reaction conditions. Together these methods are beginning to enable phase engineering of nanomaterials (PEN), i.e., the synthesis of nanomaterials with unconventional phases and the transformation between different phases, to obtain desired properties and functions. This Review summarizes the research progress in the field of PEN. First, we present representative strategies for the direct synthesis of unconventional phases and modulation of phase transformation in diverse kinds of nanomaterials. We cover the synthesis of nanomaterials ranging from metal nanostructures such as Au, Ag, Cu, Pd, and Ru, and their alloys; metal oxides, borides, and carbides; to transition metal dichalcogenides (TMDs) and 2D layered materials. We review synthesis and growth methods ranging from wet-chemical reduction and seed-mediated epitaxial growth to chemical vapor deposition (CVD), high pressure phase transformation, and electron and ion-beam irradiation. After that, we summarize the significant influence of phase on the various properties of unconventional-phase nanomaterials. We also discuss the potential applications of the developed unconventional-phase nanomaterials in different areas including catalysis, electrochemical energy storage (batteries and supercapacitors), solar cells, optoelectronics, and sensing. Finally, we discuss existing challenges and future research directions in PEN.
Drought stress induces stomatal closure and inhibits stomatal opening simultaneously. However, the underlying molecular mechanism is still largely unknown. Here, we show that the slow-type (S-type) anion channels SLAC1 and SLAH3 mainly inhibit the inward-rectifying K+ channel KAT1 by protein-protein interaction and consequently prevent stomatal opening in Arabidopsis thaliana. Voltage-clamp results demonstrated that SLAC1 inhibited KAT1 dramatically but did not inhibit KAT2. SLAH3 inhibited KAT1 to a lesser extent than did SLAC1. Both the N and C termini of SLAC1 inhibited KAT1, but the inhibition by the N terminus was stronger. The C terminus was essential for SLAC1-mediated inhibition of KAT1. Furthermore, drought stress strongly upregulated the expression of SLAC1 and SLAH3 in Arabidopsis guard cells, and the overexpression of wild-type and truncated SLAC1 dramatically impaired inward K+ (K+ in) currents of guard cells and light-induced stomatal opening. Additionally, the inhibition of KAT1 by SLAC1 and KC1 only partially overlapped, suggesting that SLAC1 and KC1 inhibited K+ in channels via different molecular mechanisms. Taken together, these findings reveal a novel regulatory mechanism for stomatal movement, in which signaling pathways for stomatal closure and opening are directly coupled by protein-protein interaction between SLAC1/SLAH3 and KAT1 in Arabidopsis.
In CO2 electroreduction, the critical bottleneck lies in the CO2 activation which requires high overpotentials. CO2 activation is related to both the electronic structures of catalysts and those of adsorbates, thus an ideal catalyst should match its electronic structures with those of the adsorbate. Here, we harmonized the electronic structures of the adsorbate and Mn-doped In2S3 nanosheets for efficient CO2 reduction. The introduction of Mn dopants into In2S3 nanosheets enhanced both the Faradaic efficiency (FE) for carbonaceous products and current density (j). At -0.9 V vs RHE, Mn-doped In2S3 nanosheets exhibited a remarkable FE of 92% for carbonaceous product at a high j of 20.1 mA cm-2. Mechanistic studies revealed that Mn doping enabled the harmonic overlaps between the p orbitals of O atoms and d orbitals of Mn atoms near the conduction band edge of Mn-doped In2S3 nanosheets during the activation of CO2. Due to the unique electronic structures of the coadsorbed configurations, Mn-doped In2S3 nanosheets exhibited an energy barrier for CO2 activation into HCOO* lower than that over pristine In2S3 nanosheets.
Probing and understanding the intrinsic active sites of electrocatalysts is crucial to unravel the underlying mechanism of CO2 electroreduction and provide a prospective for the rational design of high-performance electrocatalysts. However, their structure–activity relationships are not straightforward because electrocatalysts might reconstruct under realistic working conditions. Herein, we employ in-situ measurements to unveil the intrinsic origin of the InN nanosheets which served as an efficient electrocatalyst for CO2 reduction with a high faradaic efficiency of 95% for carbonaceous product. During the CO2 electroreduction, InN nanosheets reconstructed to form the In-rich surface. Density functional theory calculations revealed that the reconstruction of InN led to the redistribution of surface charge that significantly promoted the adsorption of HCOO* intermediates and thus benefited the formation of formate toward CO2 electroreduction. This work establishes a fundamental understanding on the mechanism associated with self-reconstruction of heterogeneous catalysts toward CO2 electroreduction.
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