Nanoscale Janus Z-Scheme Heterojunction for Boosting Artificial Photosynthesis.

Artificial photosynthesis for CO2 reduction coupled with water oxidation currently suffers from low efficiency due to inadequate interfacial charge separation of conventional Z-scheme heterojunctions. Herein, an unprecedented nanoscale Janus Z-scheme heterojunction of CsPbBr3 /TiOx is constructed for photocatalytic CO2 reduction. Benefitting from the short carrier transport distance and direct contact interface, CsPbBr3 /TiOx exhibits significantly accelerated interfacial charge transfer between CsPbBr3 and TiOx (8.90 × 108 s-1 ) compared with CsPbBr3 :TiOx counterpart (4.87 × 107 s-1 ) prepared by traditional electrostatic self-assembling. The electron consumption rate of cobalt doped CsPbBr3 /TiOx can reach as high as 405.2 ± 5.6 µmol g-1 h-1 for photocatalytic CO2 reduction to CO coupled with H2 O oxidation to O2 under AM1.5 sunlight (100 mW cm-2 ), over 11-fold higher than that of CsPbBr3 :TiOx , and surpassing the reported halide-perovskite-based photocatalysts under similar conditions. This work provides a novel strategy to boost charge transfer of photocatalysts for enhancing the performance of artificial photosynthesis.

Iris lactea var. chinensis (Fisch.) cysteine-rich gene llCDT1 enhances cadmium tolerance in yeast cells and Arabidopsis thaliana.

IlCDT1, a cysteine-rich protein, was isolated from Iris lactea var. chinensis (Fisch.) (I. lactea var. chinensis). Its transcription was up-regulated by the exogenous application of Cd. The truncated IlCDT1 (25-54) containing 14 Cys residues confers Cd tolerance to yeast as the intact IlCDT1, indicating that Cys residues are required for Cd tolerance presumably by chelating Cd. When the gene was constitutively expressed in A. thaliana, root length of transgenic lines was longer than that of wild-type under 100 µM or 200 µM Cd stress. However, Cd absorption in wild-type was more than in two trangenic lines under 100 µM Cd exposure. IlCDT1 may directly bind Cd, through chelating Cd and avoiding the Cd uptake into the cells. Together, IlCDT1 may be a promising gene for the Cd tolerance improvement. SUMMARY: Cysteine-rich gene llCDT1 enhances cadmium tolerance in yeast cells and Arabidopsis thaliana.

The over-expression of Chrysanthemum crassum CcSOS1 improves the salinity tolerance of chrysanthemum.

Soil salinity represents a major constraint on plant growth. Here, we report that the over-expression of the Chrysanthemum crassum plasma membrane Na(+)/H(+) antiporter gene CcSOS1, driven by the CaMV 35S promoter, improved the salinity tolerance of chrysanthemum 'Jinba'. In salinity-stressed transgenic plants, both the proportion of the leaf area suffering damage and the electrical conductivity of the leaf were lower in the transgenic lines than in salinity-stressed wild type plants. After a 6 day exposure to 200 mM NaCl, the leaf content of both chlorophyll (a+b) and proline was higher in the transgenic than in the wild type plants. The activity of both superoxide dismutase and peroxidase was higher in the transgenic than in the wild type plants throughout the period of NaCl stress. The transgenic plants had a stronger control over the ingress of Na(+) into the plant, particularly with respect to the youngest leaves, and so maintained a more favorable K(+)/Na(+) ratio. The result suggests that a possible strategy for improving the salinity tolerance of chrysanthemum could target the restriction of Na(+) accumulation. This study is the first to report the transgenic expression of a Na(+) efflux carrier in chrysanthemum.

Construction of a BiVO4/VS-MoS2 S-scheme heterojunction for efficient photocatalytic nitrogen fixation.

Photocatalytic nitrogen (N2) reduction to ammonia (NH3), adopting H2O as the electron source, suffers from low efficiency owing to the sluggish kinetics of N2 reduction and the requirement of a substantial thermodynamic driving force. Herein, we present a straightforward approach for the construction of an S-scheme heterojunction of BiVO4/VS-MoS2 to successfully achieve photocatalytic N2 fixation, which is manufactured by coupling an N2-activation component (VS-MoS2 nanosheet) and water-oxidation module (BiVO4 nanocrystal) through electrostatic self-assembly. The VS-MoS2 nanosheet, enriched with sulfur vacancies, plays a pivotal role in facilitating N2 adsorption and activation. Additionally, the construction of the S-scheme heterojunction enhances the driving force for water oxidation and improves charge separation. Under simulated sunlight irradiation (100 mW cm-2), BiVO4/VS-MoS2 exhibits efficient photocatalytic N2 reduction activity with H2O as the proton source, yielding NH3 at a rate of 132.8 µmol g-1 h-1, nearly 7 times higher than that of pure VS-MoS2. This study serves as a noteworthy example of efficient N2 reduction to NH3 under mild conditions.

Candidate reference genes for gene expression studies in water lily.

The selection of an appropriate reference gene(s) is a prerequisite for the proper interpretation of quantitative Real-Time polymerase chain reaction data. We report the evaluation of eight candidate reference genes across various tissues and treatments in the water lily by the two software packages geNorm and NormFinder. Across all samples, clathrin adaptor complexes medium subunit (AP47) and actin 11 (ACT11) emerged as the most suitable reference genes. Across different tissues, ACT11 and elongation factor 1-alpha (EF1alpha) exhibited a stable expression pattern. ACT11 and AP47 also stably expressed in roots subjected to various treatments, but in the leaves of the same plants the most stably expressed genes were ubiquitin-conjugating enzyme 16 (UBC16) and ACT11.

In Situ Coating CsPbBr3 Nanocrystals with Graphdiyne to Boost the Activity and Stability of Photocatalytic CO2 Reduction.

The instability and low inferior catalytic activity of metal-halide perovskite nanocrystals are crucial issues for promoting their practical application in the photocatalytic field. Herein, we in situ coat a thin graphdiyne (GDY) layer on CsPbBr3 nanocrystals based on a facile microwave synthesis method, and employ it as a photocatalyst for CO2 reduction. Under the protection of GDY, the CsPbBr3-based photocatalyst delivers significantly improved stability in a photocatalytic system containing water concomitant with enhanced CO2 uptake capacity. The favorable energy offset and close contact between CsPbBr3 and GDY trigger swift photogenerated electron transfer from CsPbBr3 to doping metal sites in GDY, boosting a remarkable improvement in the photocatalytic performance for CO2 reduction. Without adding traditional sacrificial reductants, the cobalt-doped photocatalyst achieves a high yield of 27.7 µmol g-1 h-1 for photocatalytic CO2 conversion to CO based on water as a desirable electron source, which is about 8 times higher than that of pristine CsPbBr3 nanocrystals.

The constitutive expression of a two transgene construct enhances the abiotic stress tolerance of chrysanthemum.

Various abiotic stresses downgrade the quality and productivity of chrysanthemum. A construct carrying both CcSOS1 (from Chrysanthemum crassum) and CdICE1 (from Chrysanthemum dichrum) was constitutively expressed in the chrysanthemum variety 'Jinba'. The transgenic plants were superior to the wild type (WT) ones with respect to their sensitivity to low temperature, drought and salinity, as measured by visible damage and plant survival. Salinity stressed transgenic plants accumulated more proline, and their level of superoxide dismutase and peroxidase activity was higher than in WT plants. At the physiological level, they suffered less loss of viable leaf area, maintained a lower leaf electrolyte conductivity and retained more chlorophyll (a+b). The ratio between the K(+) and Na(+) content was higher in the root, stem and median leaves of salinity stressed transgenic plants than in those of WT plants.

Identification and expression of an APETALA2-like gene from Nelumbo nucifera.

Arabidopsis transcription factor APETALA2 (AP2) controls multiple aspects of plant growth and development, including seed development, stem cell maintenance, and specification of floral organ identity. Based on sequence similar of Arabidopsis AP2 and its homologues genes from other plant species, degenerate RT-PCR and rapid amplification of cDNA ends assay were used to clone AP2 genes from lotus (Nelumbo nucifera). A 2,048-bp cDNA fragment was obtained, which contains a 1,536-bp open reading frame encoding a protein of 511 amino acids. The protein contains two AP2 domains that are conserved in AP2 proteins from other plant species, thus was named as N. nucifera APETALA2 (NnAP2). Quantitative RT-PCR revealed that NnAP2 gene was expressed in flowers, roots, leaves, and stems of N. nucifera, with flowers which have the highest transcript levels. Further analysis showed that in all five lotus cultivars examined, including "Zhongguogudailian," "Yaoniangyujiao," "Jinxia," "Hongtailian," and "Yiliangqianban," petals always have the highest expression levels when compared with the other four flower organs, though the number of petals in these cultivars ranged from simple to thousands. However, NnAP2 expression level in four nonsimple petal flower cultivars was higher than that in the simple petal flower cultivar Zhongguogudailian, indicating that NnAP2 may play a role in specification of petal identity during the evolutionary process of the ancient species N. nucifera.

Heterologous expression of a Nelumbo nucifera phytochelatin synthase gene enhances cadmium tolerance in Arabidopsis thaliana.

Phytochelatin synthase (PCS) is a key enzyme involved in the synthesis of phytochelatins, which are thought to play important roles in heavy metal detoxification. The sacred lotus (Nelumbo nucifera), one of the most popular ornamental species, has been shown to be a potential phytoremediator of heavy metal polluted water. However, the phytochelatin synthase gene in N. nucifera has not been identified yet. Here, we report the isolation and function characterization of a N. nucifera homologue of phytochelatin synthase. The sequence obtained shares a high degree of similarity with PCSs from other plant species and was named as Nelumbo nucifera phytochelatin synthase1 (NnPCS1). By using quantitative RT-PCR, we found that the expression of NnPCS1 in leaves of N. nucifera was dramatically increased in response to Cadmium (Cd) treatment. We further showed that, when exposed to Cd stress, Arabidopsis transgenic plants heterologous expressing NnPCS1 accumulated more Cd when compared with wild type. These results suggest that NnPCS1 involved in the response of N. nucifera to Cd stress and may represent a useful target gene for the phytoremediation of Cd-polluted water.

Reference gene selection for quantitative real-time PCR in Chrysanthemum subjected to biotic and abiotic stress.

Quantitative real-time PCR (RT-qPCR) is a reliable method for assessing gene expression, provided that suitable reference genes are included to normalize the data. The stability of expression of eight potential reference genes, namely, tubulin (alpha-2,4 tubulin), actin, EF1 α (elongation factor 1 α), UBC (ubiquitin C), GAPDH (glyceraldehyde-3-phosphate dehydrogenase), psaA (photosynthesis-related plastid gene representing photosystem I), PP2Acs (catalytic subunit of protein phosphatase 2A), and PGK (phosphoglycerate kinase), was assessed in chrysanthemum plants subjected to aphid infestation, heat stress or waterlogging stress using geNorm software. The widely used reference gene EF1 α performed well for aphid infested plants but poorly for waterlogged ones. The catalytic subunit of protein phosphatase 2A (PP2Acs) was the best performing one during heat and waterlogging stress, but was the worst during aphid infestation. The commonly used reference gene actin was generally the least stable of the set. No single gene was suitable for normalization on its own. The choice of reference gene(s) is an important factor in gene expression studies based on RT-qPCR.

Chrysanthemum leaf epidermal surface morphology and antioxidant and defense enzyme activity in response to aphid infestation.

Artificial aphid infestation experiments on the three chrysanthemum cultivars 'Keiun', 'Han6' and 'Jinba' showed that the three cultivars vary markedly in their resistance. Of the three cultivars, the most resistant ('Keiun') produced the longest, highest and densest trichomes, the largest and fullest gland cells, and the most wax on the lower leaf epidermis. Superoxide dismutase (EC 1.15.1.1), peroxidase (EC 1.11.1.7), ascorbate peroxidase (EC 1.11.1.11), polyphenol oxidase activity (EC 1.14.18.1) and phenylalanine ammonia lyase (EC 4.3.1.5) were enhanced by aphid herbivory. In the two more resistant cultivars ('Keiun' and 'Han6'), the activity of superoxide dismutase and ascorbate peroxidase enzymes rapidly increased following infestation, and their levels remained high from seventy-two to one hundred and sixty-eight hours after inoculation. We suggest that these two antioxidant enzymes contribute to aphid resistance of these chrysanthemum cultivars. All three cultivars showed quick responses to aphid infestation by increasing polyphenol oxidase and phenylalanine ammonia lyase activities during the early period after inoculation. Activities of these two defense enzymes were higher in the two resistant cultivars after 72h after inoculation, suggesting involvement of these two enzymes in aphid resistance.