Integrated analysis of transcriptomics and metabolomics of garden asparagus (Asparagus officinalis L.) under drought stress.

BACKGROUND: Drought is a leading environmental factor affecting plant growth. To explore the drought tolerance mechanism of asparagus, this study analyzed the responses of two asparagus varieties, namely, 'Jilv3' (drought tolerant) and 'Pacific Early' (drought sensitive), to drought stress using metabolomics and transcriptomics. RESULTS: In total, 2,567 and 7,187 differentially expressed genes (DEGs) were identified in 'Pacific Early' and 'Jilv3', respectively, by comparing the transcriptome expression patterns between the normal watering treatment and the drought stress treatment. These DEGs were significantly enriched in the amino acid biosynthesis, carbon metabolism, phenylpropanoid biosynthesis, and plant hormone signal transduction pathways. In 'Jilv3', DEGs were also enriched in the following energy metabolism-related pathways: citrate cycle (TCA cycle), glycolysis/gluconeogenesis, and pyruvate metabolism. This study also identified 112 and 254 differentially accumulated metabolites (DAMs) in 'Pacific Early' and 'Jilv3' under drought stress compared with normal watering, respectively. The amino acid, flavonoid, organic acid, and soluble sugar contents were more significantly enhanced in 'Jilv3' than in 'Pacific Early'. According to the metabolome and transcriptome analysis, in 'Jilv3', the energy supply of the TCA cycle was improved, and flavonoid biosynthesis increased. As a result, its adaptability to drought stress improved. CONCLUSIONS: These findings help to better reveal the molecular mechanism underlying how asparagus responds to drought stress and improve researchers' ability to screen drought-tolerant asparagus varieties as well as breed new varieties.

An Efficient Electron Donor for Conjugated Microporous Polymer Photocatalysts with High Photocatalytic Hydrogen Evolution Activity.

Conjugated microporous polymers (CMPs) with donor-acceptor (D-A) molecular structure show high photocatalytic activity for hydrogen evolution due to the efficient light-induced electron/hole separation, which is mostly determined by the nature of electron donor and acceptor units. Therefore, the selection of electron donor and acceptor holds the key point to construct high performance polymer photocatalysts. Herein, two dibenzo[b,d]thiophene-S,S-dioxide (BTDO) containing CMP photocatalysts using tetraphenylethylene (TPE) or dibenzo[g,p]chrysene (DBC) as the electron donor to investigate the influence of the geometry of electron donor on the photocatalytic activity are design and synthesized. Compared with the twisted TPE donor, DBC has a planar molecular structure with extended π-conjugation, which promotes the charges transmission and light-induced electron/hole separation. As a result, the polymer DBC-BTDO produced from DBC donor shows a remarkable photocatalytic hydrogen evolution rate (HER) of 104.86 mmol h-1  g-1 under full arc light (λ > 300 nm), which is much higher than that of the polymer TPE-BTDO (1.80 mmol h-1  g-1 ), demonstrating that DBC can be an efficient electron donor for constructing D-A polymer photocatalysts with high photocatalytic activity for hydrogen evolution.

Transcriptional programming and functional interactions within the Phytophthora sojae RXLR effector repertoire.

The genome of the soybean pathogen Phytophthora sojae contains nearly 400 genes encoding candidate effector proteins carrying the host cell entry motif RXLR-dEER. Here, we report a broad survey of the transcription, variation, and functions of a large sample of the P. sojae candidate effectors. Forty-five (12%) effector genes showed high levels of polymorphism among P. sojae isolates and significant evidence for positive selection. Of 169 effectors tested, most could suppress programmed cell death triggered by BAX, effectors, and/or the PAMP INF1, while several triggered cell death themselves. Among the most strongly expressed effectors, one immediate-early class was highly expressed even prior to infection and was further induced 2- to 10-fold following infection. A second early class, including several that triggered cell death, was weakly expressed prior to infection but induced 20- to 120-fold during the first 12 h of infection. The most strongly expressed immediate-early effectors could suppress the cell death triggered by several early effectors, and most early effectors could suppress INF1-triggered cell death, suggesting the two classes of effectors may target different functional branches of the defense response. In support of this hypothesis, misexpression of key immediate-early and early effectors severely reduced the virulence of P. sojae transformants.

Rational design of triazine-based conjugated polymers with enhanced charge separation ability for photocatalytic hydrogen evolution.

Triazine-based conjugated polymers (TCPs) are promising organic catalysts for green H2 production, since their photocatalytic performance can be easily regulated via appropriate molecular design. However, apart from weak absorption of visible light, weak charge separation and transport abilities also considerably restrict the photocatalytic performance of TCPs. Herein, we report two novel TCP photocatalysts with donor-acceptor (D-A) and donor-π-acceptor (D-π-A) structures using dibenzo[g,p]chrysene (Dc), thiophene (T), and 2,4,6-triphenyl-1,3,5-triazine (Tz) as the donor, π-spacer, and acceptor, respectively. Compared to Dc-Tz with a D-A structure, Dc-T-Tz exhibits a broader light absorption edge and more efficient charge separation and transmission due to its D-π-A structure and strong dipole effect. These properties enable Dc-T-Tz to display a prominent H2 production rate of 45.13 mmol h-1 g-1 under ultraviolet-visible (UV-Vis) light (λ > 300 nm). Therefore, Dc-T-Tz represents state-of-the-art TCP photocatalysts to date.

Molecular Engineering in D-π-A-A-Type Conjugated Microporous Polymers for Boosting Photocatalytic Hydrogen Evolution.

Conjugated microporous polymer (CMP) photocatalysts with donor-π-acceptor (D-π-A) or donor-acceptor (D-A) structures have garnered great attention for solar-driven hydrogen generation because of their inherent charge separation nature and high surface area. Herein, we design a series of D-π-A-A-type CMP photocatalysts to uncover the influence of the content of the dibenzo[b,d]thiophene-S-S-dioxide (BTDO) acceptor on the photocatalytic activity. The results demonstrate that the acceptor content in the D-π-A-A-type CMP photocatalysts affects the electronic structure, the availability of reaction sites, and the separation between light-generated electrons and holes, which mainly determine the photocatalytic performance for H2 release. Benefiting from the synergy of light absorption, hydrophilicity, and active sites, the bare polymer PyT-BTDO-2 with an optimized BTDO content exhibits a high H2 production rate of 230.06 mmol h-1 g-1 under simulated sunlight, manifesting that the strategy of D-π-A-A structural design is efficacious for boosting the photocatalytic performance of CMP photocatalysts.

An efficient electron donor containing a silicon heteroatom for organic photocatalysts with high hydrogen production activity.

We report here 4,4-bis(2-ethylhexyl)-4H-silolo[3,2-b:4,5-b']dithiophene (SiDT) as an electron donor to construct a donor-acceptor type conjugated polymer (PSiDT-BTDO) photocatalyst with a narrow band gap by employing dibenzo[b,d]thiophene-S,S-dioxide as an electron acceptor. The resulting polymer PSiDT-BTDO could realize a high hydrogen evolution rate of 72.20 mmol h-1 g-1 under ultraviolet-visible light with a Pt co-catalyst, due to the enhanced hydrophilicity as well as the decreased recombination rate of photo-induced holes/electrons and the dihedral angles of the polymer chains. The high photocatalytic activity of PSiDT-BTDO reveals the promising application of the SiDT donor in designing high-performance organic photocatalysts for hydrogen evolution.

Combined full-length transcriptomic and metabolomic analysis reveals the regulatory mechanisms of adaptation to salt stress in asparagus.

Soil salinity is a very serious abiotic stressor that affects plant growth and threatens crop yield. Thus, it is important to explore the mechanisms of salt tolerance of plant and then to stabilize and improve crop yield. Asparagus is an important cash crop, but its salt tolerance mechanisms are largely unknown. Full-length transcriptomic and metabolomic analyses were performed on two asparagus genotypes: 'jx1502' (a salt-tolerant genotype) and 'gold crown' (a salt-sensitive genotype). Compared with the distilled water treatment (control), 877 and 1610 differentially expressed genes (DEGs) were identified in 'jx1502' and 'gold crown' under salt stress treatment, respectively, and 135 and 73 differentially accumulated metabolites (DAMs) were identified in 'jx1502' and 'gold crown' under salt stress treatment, respectively. DEGs related to ion transport, plant hormone response, and cell division and growth presented differential expression profiles between 'jx1502' and 'gold crown.' In 'jx1502,' 11 ion transport-related DEGs, 8 plant hormone response-related DEGs, and 12 cell division and growth-related DEGs were upregulated, while 7 ion transport-related DEGs, 4 plant hormone response-related DEGs, and 2 cell division and growth-related DEGs were downregulated. Interestingly, in 'gold crown,' 14 ion transport-related DEGs, 2 plant hormone response-related DEGs, and 6 cell division and growth-related DEGs were upregulated, while 45 ion transport-related DEGs, 13 plant hormone response-related DEGs, and 16 cell division and growth-related DEGs were downregulated. Genotype 'jx1502' can modulate K+/Na+ and water homeostasis and maintain a more constant transport system for nutrient uptake and distribution than 'gold crown' under salt stress. Genotype 'jx1502' strengthened the response to auxin (IAA), as well as cell division and growth for root remodeling and thus salt tolerance. Therefore, the integration analysis of transcriptomic and metabolomic indicated that 'jx1502' enhanced sugar and amino acid metabolism for energy supply and osmotic regulatory substance accumulation to meet the demands of protective mechanisms against salt stress. This work contributed to reveal the underlying salt tolerance mechanism of asparagus at transcription and metabolism level and proposed new directions for asparagus variety improvement.

Quinone-based conjugated polymer cathodes synthesized via direct arylation for high performance Li-organic batteries.

Direct arylation cross-coupling reaction was employed to prepare quinone-based conjugated polymer cathodes, which realize a high reversible capacity of 200 mA h g-1 at 0.05 A g-1, an excellent rate capability of 111 mA h g-1 at 30 A g-1 (150C), and a stable cycling performance for more than 3000 cycles.

Synthetic Control of Electronic Property and Porosity in Anthraquinone-Based Conjugated Polymer Cathodes for High-Rate and Long-Cycle-Life Na-Organic Batteries.

Redox-active carbonyl-containing compounds have received extensive attention as cathode materials for sodium-ion batteries (SIBs) because of their excellent attributes, including elemental sustainability, high theoretical capacity, diverse structures, and tunable properties. However, the storage of Na+ in most carbonyl-based cathode materials is plagued by the low capacity, unsatisfying rate performance, and short cycling life. Herein, we develop a series of anthraquinone-based conjugated polymer cathodes consisting of anthraquinone and benzene with different linking patterns. It reveals that the linkage sites on benzene ring could affect the electronic structures of the resulting polymers and thus their charge-storage capabilities. The 1,2,4,5-linkage on benzene leads to a high surface area, a narrow band gap, and the lowest unoccupied molecular orbital for the resulting polymer PBAQ-3. As a cathode for SIBs, it delivers a high capacity of around 200 mAh g-1 and excellent rate performance (105 mAh g-1 at 200 C) as well as stable cycling with a capacity retention of 95.8% after 1000 cycles at 0.05 A g-1 and 83.1% after 40000 cycles at 3 A g-1. Our findings highlight the influence of linking patterns of the building blocks on the electrochemical performance of organic electrodes.

A Zn-S aqueous primary battery with high energy and flat discharge plateau.

We demonstrate a disposable aqueous primary battery chemistry that comprises environmentally benign materials of the sulfur cathode and Zn anode in a 1 M ZnCl2 aqueous electrolyte. The Zn-S battery shows a high energy density of 1083.3 Wh kg-1 for sulphur with a flat discharge voltage plateau around 0.7 V. When operating at a high mass loading of 8.3 mg cm-2 for sulfur in the cathode, the battery exhibits a very high areal capacity of 11.4 mA h cm-2 and areal energy of 7.7 mW h cm-2.

Boosting the Photocatalytic Hydrogen Evolution Activity for D-π-A Conjugated Microporous Polymers by Statistical Copolymerization.

Recently, great progress has been achieved in the design and preparation of conjugated organic polymer photocatalysts for hydrogen generation. However, it is still challenging to develop an organic polymer photocatalyst with high photoconversion efficiency. Rational structure design of organic polymer photocatalysts holds the key point to realize high photocatalytic performance. Herein, a series of donor-π-acceptor (D-π-A) conjugated organic copolymer photocatalysts is developed using statistical copolymerization by tuning the feed molar ratio of pyrene (donor) to dibenzothiophene-S,S-dioxide (acceptor) units. It reveals that the photocatalytic activity of the resulting copolymers is significantly dependent on the molar ratio of donor to acceptor, which efficiently changes the polymer structure and component. When the monomer feed ratio is 25:75, the random copolymer PyBS-3 of 10 mg with Pt cocatalyst shows a high hydrogen evolution rate of 1.05 mmol h-1 under UV/Vis light irradiation using ascorbic acid as the hole-scavenger, and an external quantum efficiency of 29.3% at 420 nm, which represents the state-of-the-art of organic polymer photocatalysts. This work demonstrates that statistical copolymerization is an efficient strategy to optimize the polymer structure for improving the photocatalytic activity of conjugated organic polymer catalysts.

Realizing high hydrogen evolution activity under visible light using narrow band gap organic photocatalysts.

The design and synthesis of conjugated semiconducting polymers for photocatalytic hydrogen evolution have engendered intense recent interest. However, most reported organic polymer photocatalysts show a relatively broad band gap with weak light absorption ability in the visible light region, which commonly leads to a low photocatalytic activity under visible light. Herein, we synthesize three novel dithieno[3,2-b:2',3'-d]thiophene-S,S-dioxide (DTDO) containing conjugated polymer photocatalysts by a facile C-H arylation coupling polymerization reaction. The resulting polymers show a broad visible light absorption range up to 700 nm and a narrow band gap down to 1.81 eV due to the introduction of the DTDO unit. Benefiting from the donor-acceptor polymer structure and the high content of the DTDO unit, the three-dimensional polymer PyDTDO-3 without the addition of a Pt co-catalyst shows an attractive photocatalytic hydrogen evolution rate of 16.32 mmol h-1 g-1 under visible light irradiation, which is much higher than that of most reported organic polymer photocatalysts under visible light.

Comparative transcriptome analysis of the garden asparagus (Asparagus officinalis L.) reveals the molecular mechanism for growth with arbuscular mycorrhizal fungi under salinity stress.

Soil salinity is one of the most abiotic stress factors that severely affects the growth and development of many plants, which can ultimately threaten crop yield. Arbuscular mycorrhiza fungi (AMF) has been proven to be effective in mitigating salinity stress by symbiosis in many crops. Asparagus officinalis are perennial plants grown in saline-alkaline soil, however, limited information on their molecular mechanisms has restricted efficient application of AMF to garden asparagus under salinity stress. In this study, we conducted a transcriptome analysis on the leaves of garden asparagus to identify gene expression under salinity stress. Seedlings were grown in 4 treatments, including non-inoculated AMF using distilled water (NI), inoculated AMF using distilled water (AMF), non-inoculated with salinity stress (NI + S), and inoculated with salinity stress (AMF + S). A total of 6019 novel genes were obtained based on the reference-guided assembly of the garden asparagus transcriptome. Results revealed that 455 differentially expressed genes (DEGs) were identified when comparing NI + S to AMF + S. However, among the up-regulated DEGs, 41 DEGs were down-regulated, while 242 DEGs had no differences in their expression levels when comparing NI to NI + S. These DEGs' expression patterns may be key induced by AMF under salinity stress. Additionally, the GO and KEGG enrichment analyses of 455 DEGs revealed that these genes mainly participate in the improvement of the internal environment in plant cells, nitrogen metabolic-related processes, and possible photoprotection mechanisms. These findings provide insight into enhanced salinity stress adaptation by AMF inoculation, as well as salt-tolerant candidate genes for further functional analyses.