Broomcorn millet (Panicum miliaceum L.) has strong tolerance to abiotic stresses, and is probably one of the oldest crops, with its earliest cultivation that dated back to ca. ~10,000 years. We ...report here its genome assembly through a combination of PacBio sequencing, BioNano, and Hi-C (in vivo) mapping. The 18 super scaffolds cover ~95.6% of the estimated genome (~887.8 Mb). There are 63,671 protein-coding genes annotated in this tetraploid genome. About ~86.2% of the syntenic genes in foxtail millet have two homologous copies in broomcorn millet, indicating rare gene loss after tetraploidization in broomcorn millet. Phylogenetic analysis reveals that broomcorn millet and foxtail millet diverged around ~13.1 Million years ago (Mya), while the lineage specific tetraploidization of broomcorn millet may be happened within ~5.91 million years. The genome is not only beneficial for the genome assisted breeding of broomcorn millet, but also an important resource for other Panicum species.
Summary
Plant phased small interfering RNAs (phasiRNAs) contribute to robust male fertility; however, specific functions remain undefined. In maize (Zea mays), male sterile23 (ms23), necessary for ...both 24‐nt phasiRNA precursor (24‐PHAS) loci and Dicer‐like5 (Dcl5) expression, and dcl5‐1 mutants unable to slice PHAS transcripts lack nearly all 24‐nt phasiRNAs.
Based on sequence capture bisulfite‐sequencing, we find that CHH DNA methylation of most 24‐PHAS loci is increased in meiotic anthers of control plants but not in the ms23 and dcl5 mutants.
Because dcl5‐1 anthers express PHAS precursors, we conclude that the 24‐nt phasiRNAs, rather than just activation of PHAS transcription, are required for targeting increased CHH methylation at these loci.
Although PHAS precursors are processed into multiple 24‐nt phasiRNA products, there is substantial differential product accumulation. Abundant 24‐nt phasiRNA positions corresponded to high CHH methylation within individual loci, reinforcing the conclusion that 24‐nt phasiRNAs contribute to increased CHH methylation in cis.
ABSTRACT
Anther development from stamen primordium to pollen dispersal is complex and essential to sexual reproduction. How this highly dynamic and complex developmental process is controlled ...genetically is not well understood, especially for genes involved in specific key developmental phases. Here we generated RNA sequencing libraries spanning 10 key stages across the entirety of anther development in maize (Zea mays). Global transcriptome analyses revealed distinct phases of cell division and expansion, meiosis, pollen maturation, and mature pollen, for which we detected 50, 245, 42, and 414 phase‐specific marker genes, respectively. Phase‐specific transcription factor genes were significantly enriched in the phase of meiosis. The phase‐specific expression of these marker genes was highly conserved among the maize lines Chang7‐2 and W23, indicating they might have important roles in anther development. We explored a desiccation‐related protein gene, ZmDRP1, which was exclusively expressed in the tapetum from the tetrad to the uninucleate microspore stage, by generating knockout mutants. Notably, mutants in ZmDRP1 were completely male‐sterile, with abnormal Ubisch bodies and defective pollen exine. Our work provides a glimpse into the gene expression dynamics and a valuable resource for exploring the roles of key phase‐specific genes that regulate anther development.
Next‐generation sequencing of the four key maize anther development phases based on anther length identified phase‐specific marker genes, providing a valuable resource for exploring key phase‐specific genes that play essential roles during anther development.
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•CO gas and NO gas are switched back and forth over calcium ferrite at 1000℃.•Calcium ferrite redox cycle in catalytic NO reduction by CO.•CO and NO compete for adsorption on calcium ...ferrite.•Calcium ferrite and its reduction products both function.
Steel industry nitrogen oxides (NOx) emission requirements are getting increasingly rigorous. Calcium ferrite around coal or coke fines controls the combustion of nitrogen monoxide (NO) reduction by carbon monoxide (CO) in an iron ore sintering bed. This control lacked mechanistic research. A hypothesis that it belongs to the redox mechanism. In an atmosphere of a combustion boundary layer with 13500 ppm CO and 450 ppm NO at 1000 °C, the transient-response method was used to investigate the effects of CO and NO on the calcium ferrite (CaFe2O4). The activity of CaFe2O4 and its reduction products in NO reduction was examined. The results show that CaFe2O4 features strong basic sites with NO storage capacity of 158.8 μmol/g⋅catalyst at high temperatures to promote the competitive adsorption of CO and NO. The CaFe2O4 reduction path by CO, which is not affected by NO, is CaFe2O4 → Fe-FeO- dicalcium ferrite(Ca2Fe2O5) → Fe-CaO. The reduced calcium ferrites have a catalytic effect of 100 % NO removal and display more pores. After CaFe2O4 reduction, the Fe-CaO oxidation path by NO is Fe-CaO → Fe3O4-Ca2Fe2O5 → CaFe2O4. Ca2Fe2O5 redox is also involved in the redox cycle that Ca2Fe2O5 → Fe-CaO by CO and then Fe-CaO → Ca2Fe2O5 by NO. A strategy of Fe-CaO around fuels is proposed to further improve the combustion control by expanding the reducing layer in the atmosphere and generating more Ca2Fe2O5.
The early maize (
) seed undergoes several developmental stages after double fertilization to become fully differentiated within a short period of time, but the genetic control of this highly dynamic ...and complex developmental process remains largely unknown. Here, we report a high temporal-resolution investigation of transcriptomes using 31 samples collected at an interval of 4 or 6 h within the first six days of seed development. These time-course transcriptomes were clearly separated into four distinct groups corresponding to the stages of double fertilization, coenocyte formation, cellularization, and differentiation. A total of 22,790 expressed genes including 1415 transcription factors (TFs) were detected in early stages of maize seed development. In particular, 1093 genes including 110 TFs were specifically expressed in the seed and displayed high temporal specificity by expressing only in particular period of early seed development. There were 160, 22, 112, and 569 seed-specific genes predominantly expressed in the first 16 h after pollination, coenocyte formation, cellularization, and differentiation stage, respectively. In addition, network analysis predicted 31,256 interactions among 1317 TFs and 14,540 genes. The high temporal-resolution transcriptome atlas reported here provides an important resource for future functional study to unravel the genetic control of seed development.
Abstract
Common purslane (Portulaca oleracea) integrates both C4 and crassulacean acid metabolism (CAM) photosynthesis pathways and is a promising model plant to explore C4-CAM plasticity. Here, we ...report a high-quality chromosome-level genome of nicotinamide adenine dinucleotide (NAD)-malic enzyme (ME) subtype common purslane that provides evidence for 2 rounds of whole-genome duplication (WGD) with an ancient WGD (P-β) in the common ancestor to Portulacaceae and Cactaceae around 66.30 million years ago (Mya) and another (Po-α) specific to common purslane lineage around 7.74 Mya. A larger number of gene copies encoding key enzymes/transporters involved in C4 and CAM pathways were detected in common purslane than in related species. Phylogeny, conserved functional site, and collinearity analyses revealed that the Po-α WGD produced the phosphoenolpyruvate carboxylase-encoded gene copies used for photosynthesis in common purslane, while the P-β WGD event produced 2 ancestral genes of functionally differentiated (C4- and CAM-specific) beta carbonic anhydrases involved in the C4 + CAM pathways. Additionally, cis-element enrichment analysis in the promoters showed that CAM-specific genes have recruited both evening and midnight circadian elements as well as the Abscisic acid (ABA)-independent regulatory module mediated by ethylene-response factor cis-elements. Overall, this study provides insights into the origin and evolutionary process of C4 and CAM pathways in common purslane, as well as potential targets for engineering crops by integrating C4 or CAM metabolism.
Common purslane has undergone 2 rounds of whole-genome duplication (WGD), and the ancient P-β WGD produced the ancestral genes of functional C4- and crassulacean acid metabolism (CAM)-specific gene copies involved in C4 + CAM pathways.
The early maize (Zea mays) seed undergoes several developmental stages after double fertilization to become fully differentiated within a short period of time, but the genetic control of this highly ...dynamic and complex developmental process remains largely unknown. Here, we report a high temporal-resolution investigation of transcriptomes using 31 samples collected at an interval of 4 or 6 h within the first six days of seed development. These time-course transcriptomes were clearly separated into four distinct groups corresponding to the stages of double fertilization, coenocyte formation, cellularization, and differentiation. A total of 22,790 expressed genes including 1415 transcription factors (TFs) were detected in early stages of maize seed development. In particular, 1093 genes including 110 TFs were specifically expressed in the seed and displayed high temporal specificity by expressing only in particular period of early seed development. There were 160, 22, 112, and 569 seed-specific genes predominantly expressed in the first 16 h after pollination, coenocyte formation, cellularization, and differentiation stage, respectively. In addition, network analysis predicted 31,256 interactions among 1317 TFs and 14,540 genes. The high temporal-resolution transcriptome atlas reported here provides an important resource for future functional study to unravel the genetic control of seed development.
Inspired by the assembly of Lego toys, hydrogel building blocks with heterogeneous responsiveness are assembled utilizing macroscopic supramolecular recognition as the adhesion force. The Lego ...hydrogel provides 3D transformation upon pH variation. After disassembly of the building blocks by changing the oxidation state, they can be re‐assembled into a completely new shape.
This work shows the solar-driven dehydrogenative coupling of methane to ethane at room temperature. A solar-to-C 2 H 6 energy conversion efficiency of 0.08% was achieved on the polar surface of ...Au/ZnO porous nanosheets (NSs), where methane C–H bonds are polarized and dissociated by the local electric field normal to the polar {001} plane, and finally converted into ethane and hydrogen through a radical coupling pathway. Mechanistic studies suggest that the Au-plasmon-induced resonance energy transfer modulates charge carrier energetics to trigger the stoichiometric conversion. Hot electrons reduce protons to H 2 , which is the rate-determining step of methane coupling.
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