Improving Tuber Yield of Tiger Nut (Cyperus esculentus L.) through Nitrogen Fertilization in Sandy Farmland.

The cultivation of tiger nut (Cyperus esculentus L.) on marginal lands is a feasible and effective way to increase food production in Northern China. However, the specific influence of nitrogen fertilizer application on the growth dynamics, tuber expansion, overall yield, and nitrogen use efficiency (NUE) of tiger nuts cultivated on these sandy lands is yet to be fully elucidated. From 2021 to 2022, we conducted a study to determine the effect of N fertilizers on the leaf function morphology, canopy apparent photosynthesis (CAP), tuber yield, and NUE of tiger nut. The results indicate that the tuber yield and NUE are closely related to the specific leaf area (SLA), leaf area index (LAI), leaf nitrogen concentration per area (NA), CAP, and tuber expansion characteristics. Notably, significant enhancements in the SLA, LAI, NA, and CAP during the tuber expansion phase ranging from the 15th to the 45th day under the 300 kg N ha-1 treatment were observed, subsequently leading to increases in both the tuber yield and NUE. Moreover, a maximum average tuber filling rate was obtained under the N300 treatment. These improvements led to substantial increases in the tuber yield (32.1-35.5%), nitrogen agronomic efficiency (NAE, 2.1-5.3%), nitrogen partial factor productivity (NPP, 4.8-8.1%), and nitrogen recovery efficiency (NRE, 3.4-5.7%). Consequently, 300 kg N ha-1 of N fertilizers is the most effective dose for optimizing both the yield of tiger nut tubers and the NUE of tiger nut plants in marginal soils. Structural equation modeling reveals that N application affects the yield and NUE through its effects on leaf functional traits, the CAP, and the tuber filling characteristics. Modeling indicates that tuber expansion characteristics primarily impact the yield, while CAP predominantly governs the NUE. Above all, this study highlights the crucial role of N fertilizer in maximizing the tiger nut tuber yield potential on marginal lands, providing valuable insights into sustainable farming in dry areas.

Effects of maize and soybean intercropping on soil phosphorus bioavailability and microbial community structure in rhizosphere.

To investigate the effect of maize/soybean intercropping on rhizosphere soil microbial communities and phosphorus (P) bioavailability, we examined the changes of soil bioavailable P fractions and microbial community characteristics in the monoculture and intercropping systems based on high-throughput sequencing. The results showed that maize/soybean intercropping increased the contents of rhizosphere soil organic matter (SOM), available phosphorus (AP), microbial biomass phosphorus (MBP), and aboveground biomass. The increase of AP was mainly related to the increasing enzyme extracted phosphorus (Enzyme-P) and hydrochloric acid extracted phosphorus (HCl-P) contents. The dominant bacterial phyla under each treatment were Proteobacteria, Actinobacteria, Acidobacteria and Chloroflexi, while the dominant bacterial genera were Nocardioides, Solirubacter, Sphingomonas and Arthrobacter, with Proteobacteria and Sphingomonas having the highest relative abundance. The relative abundance of Proteobacteria and Sphingomonas in intercropping maize rhizosphere soil was significantly higher than that in monoculture, and that of Proteobacteria in intercropping soybean rhizosphere soil was significantly higher than monoculture. Soil properties and P fractions were closely related to the rhizosphere soil microbial composition. In all, maize/soybean intercropping could affect the rhizosphere soil P bioavailability by altering the structure of rhizosphere microbial communities.

Overexpression of TaLAX3-1B alters the stomatal aperture and improves the salt stress resistance of tobacco.

BACKGROUND: Stomata, which play important roles in both optimizing photosynthesis efficiency and adapting to stress, are closely related to IAA and ABA. In plants, the auxin influx carrier LAX3 has been found to play roles in development and stress tolerance. However, the function of LAX3 in stomata and in response to salt stress remains largely unknown. METHODS AND RESULTS: Here, we show that overexpression of wheat TaLAX3-1B in tobacco results in a decrease in stomatal aperture and a relatively closed state of the stomata. In addition, the stomatal movement of the OxTaLAX3-1B lines was less sensitive to ABA than that of the WT. Consistently, compared with the WT, the OxTaLAX3-1B lines showed significantly higher expression of stomate-, IAA- and ABA-related genes and endogenous IAA and ABA contents. Furthermore, compared with the WT, the OxTaLAX3-1B lines exhibited higher proline content, salt stress-related gene expression and ROS antioxidant enzyme activity but lower MDA content and ROS accumulation after salt treatment. CONCLUSIONS: The present results suggest that TaLAX3-1B plays a positive role in regulating stomatal closure and enhancing salt stress tolerance.

Genetic mapping of powdery mildew resistance genes in wheat landrace Guizi 1 via genotyping by sequencing.

BACKGROUND: Wheat (Triticum aestivum L.) powdery mildew (Pm), which caused by Blumeria graminis f. sp. tritici (Bgt), is a destructive disease worldwide that causes severe yield losses in wheat. Resistant wheat cultivars easily lose their ability to effectively resist newly emerged Bgt strains; therefore, identifying new resistance genes is necessary for breeding resistant cultivars. METHODS AND RESULTS: Guizi 1 (GZ1) is a Chinese wheat cultivar with moderate and stable resistance to Pm. Genetic analysis indicated that the Pm resistance of GZ1 was controlled by a single dominant gene, designated PmGZ1. In total, 110 F2 individual plants and their 2 parents were subjected to genotyping by sequencing (GBS), which yielded 23,134 high-quality single-nucleotide polymorphisms (SNPs). The SNP distributions across the 21 chromosomes ranged from 134 on chromosome 6D to 6288 on chromosome 3B. Chromosome 6A has 1866 SNPs, among which 16 are physically located between positions 307,802,221 and 309,885,836 in an approximate 2.3-cM region; this region also had the greatest SNP density. The average map distance between SNP markers was 0.1 cM. A quantitative trait locus (QTL) with a significant epistatic effect on Pm resistance was mapped to chromosome 6A. The logarithm of odds (LOD) value of PmGZ1 was 34.8, and PmGZ1 was located within the confidence interval marked by chr6a-307802221 and chr6a-309885836. Moreover, 74.7% of the phenotypic variance was explained by PmGZ1. Four candidate genes (which encoded two TaAP2-A and two actin proteins) were annotated maybe as resistance genes. CONCLUSIONS: The present results provide valuable information for wheat genetic improvement, QTL fine mapping, and candidate gene validation.

TmNAS3 from Triticum monococum directly regulated by TmbHLH47 increases Fe content of wheat grain.

Biofortification is an effective way to enhance wheat grain Fe content. However, Fe overload inhibits the growth and development of wheat. In this work, the impact of Triticum monococcum nicotianamine synthase 3 (TmNAS3) on Fe accumulation in wheat grain was analyzed. Transgenic wheat expressing TmNAS3 was obtained via Agrobacterium-mediated transformation. The concentrations of Fe in the grains of two transgenic wheat lines were 62.42 µg/g and 68.75 µg/g, while that in the non-transgenic line (NT) was only 29.51 µg/g. Exogenous Fe application induced the expression of natural resistance-associated macrophage protein 3 (NRAMP3), NRAMP6, yellow stripe-like protein 3 (YSL3), YSL6, and vacuolar iron transporter 2 in transgenic wheat. The transcription factor that bound to the TmNAS3 promoter was identified, and the findings suggested that TmbHLH47 directly interacted and promoted the transcription of TmNAS3. Moreover, TmbHLH47 was observed to bind directly to the G-box in TmNAS3 promoter and regulated the transcriptional level of TmNAS3. Our findings contribute a TmbHLH47/TmNAS3 transcriptional pathway and thereby provide a potential strategy for improving the Fe concentration of wheat through genetic engineering.

Genome-wide analysis of the Tritipyrum WRKY gene family and the response of TtWRKY256 in salt-tolerance.

Introduction: The transcription factor WRKY is widespread in the plant kingdom and plays a crucial role in diverse abiotic stress responses in plant species. Tritipyrum, an octoploid derived from an intergeneric cross between Triticum aestivum (AABBDD) and Thinopyrum elongatum (EE), is a valuable germplasm resource for introducing superior traits of Th. elongatum into T. aestivum. The recent release of the complete genome sequences of T. aestivum and Th. elongatum enabled us to investigate the organization and expression profiling of Tritipyrum WRKY genes across the entire genome. Results: In this study, 346 WRKY genes, from TtWRKY1 to TtWRKY346, were identified in Tritipyrum. The phylogenetic analysis grouped these genes into three subfamilies (I-III), and members of the same subfamilies shared a conserved motif composition. The 346 TtWRKY genes were dispersed unevenly across 28 chromosomes, with 218 duplicates. Analysis of synteny suggests that the WRKY gene family may have a common ancestor. Expression profiles derived from transcriptome data and qPCR demonstrated that 54 TtWRKY genes exhibited relatively high levels of expression across various salt stresses and recovery treatments. Tel1E01T143800 (TtWRKY256) is extremely sensitive to salt stress and is on the same evolutionary branch as the salt-tolerant A. thaliana genes AtWRKY25 and AtWRKY33. From 'Y1805', the novel AtWRKY25 was cloned. The Pearson correlation analysis identified 181 genes that were positively correlated (R>0.9) with the expression of TtWRKY256, and these genes were mainly enriched in metabolic processes, cellular processes, response to stimulus, biological regulation, and regulation of biological. Subcellular localization and qRT-PCR analysis revealed that TtWRKY256 was located in the nucleus and was highly expressed in roots, stems, and leaves under salt stress. Discussion: The above results suggest that TtWRKY256 may be associated with salt stress tolerance in plants and may be a valuable alien gene for improving salt tolerance in wheat.

The BAG2 and BAG6 Genes Are Involved in Multiple Abiotic Stress Tolerances in Arabidopsis Thaliana.

The BAG proteins are a family of multi-functional co-chaperones. In plants, BAG proteins were found to play roles both in abiotic and biotic stress tolerance. However, the function of Arabidopsis BAG2 remains largely unknown, whereas BAG6 is required for plants' defense to pathogens, although it remains unknown whether BAG6 is involved in plants' tolerance to abiotic stresses. Here, we show that both BAG2 and BAG6 are expressed in various tissues and are upregulated by salt, mannitol, and heat treatments and by stress-related hormones including ABA, ethylene, and SA. Germination of bag2, bag6 and bag2 bag6 seeds is less sensitive to ABA compared to the wild type (WT), whereas BAG2 and BAG6 overexpression lines are hypersensitive to ABA. bag2, bag6, and bag2 bag6 plants show higher survival rates than WT in drought treatment but display lower survival rates in heat-stress treatment. Consistently, these mutants showed differential expression of several stress- and ABA-related genes such as RD29A, RD29B, NCED3 and ABI4 compared to the WT. Furthermore, these mutants exhibit lower levels of ROS after drought and ABA treatment but higher ROS accumulation after heat treatment than the WT. These results suggest that BAG2 and BAG6 are negatively involved in drought stress but play a positive role in heat stress in Arabidopsis.

Chronic mitochondrial calcium elevation suppresses leaf senescence.

Mitochondria Ca2+ overload has long been recognized as a cell death trigger. Unexpectedly, we demonstrated a signaling complex composed of Calmodulin (CaM), Arabidopsis thaliana Bcl-2-associated athanogene 5 (AtBAG5) and Heat-shock cognate 70 protein (Hsc70) within Arabidopsis thaliana mitochondria which transduces mitochondria Ca2+ elevations to suppress leaf senescence. Gain- and loss-of-function AtBAG5 mutant plants revealed that, mitochondria Ca2+ elevation significantly increase chlorophyll retention and decrease H2O2 level in dark-induced leaf senescence assay. Based on our findings, we proposed a molecular mechanism in which chronic mitochondria Ca2+ elevation reduced ROS levels and thus inhibits leaf senescence.

CaM/BAG5/Hsc70 signaling complex dynamically regulates leaf senescence.

Calcium signaling plays an essential role in plant cell physiology, and chaperone-mediated protein folding directly regulates plant programmed cell death. The Arabidopsis thaliana protein AtBAG5 (Bcl-2-associated athanogene 5) is unique in that it contains both a BAG domain capable of binding Hsc70 (Heat shock cognate protein 70) and a characteristic IQ motif that is specific for Ca(2+)-free CaM (Calmodulin) binding and hence acts as a hub linking calcium signaling and the chaperone system. Here, we determined crystal structures of AtBAG5 alone and in complex with Ca(2+)-free CaM. Structural and biochemical studies revealed that Ca(2+)-free CaM and Hsc70 bind AtBAG5 independently, whereas Ca(2+)-saturated CaM and Hsc70 bind AtBAG5 with negative cooperativity. Further in vivo studies confirmed that AtBAG5 localizes to mitochondria and that its overexpression leads to leaf senescence symptoms including decreased chlorophyll retention and massive ROS production in dark-induced plants. Mutants interfering the CaM/AtBAG5/Hsc70 complex formation leads to different phenotype of leaf senescence. Collectively, we propose that the CaM/AtBAG5/Hsc70 signaling complex plays an important role in regulating plant senescence.

Subnanometer Molybdenum Sulfide on Carbon Nanotubes as a Highly Active and Stable Electrocatalyst for Hydrogen Evolution Reaction.

Electrochemically splitting water for hydrogen evolution reaction (HER) has been viewed as a promising approach to produce renewable and clean hydrogen energy. However, searching for cheap and efficient HER electrocatalysts to replace the currently used Pt-based catalysts remains an urgent task. Herein, we develop a one-step carbon nanotube (CNT) assisted synthesis strategy with CNTs' strong adsorbability to mediate the growth of subnanometer-sized MoS(x) on CNTs. The subnanometer MoS(x)-CNT hybrids achieve a low overpotential of 106 mV at 10 mA cm(-2), a small Tafel slope of 37 mV per decade, and an unprecedentedly high turnover frequency value of 18.84 s(-1) at η = 200 mV among all reported non-Pt catalysts in acidic conditions. The superior performance of the hybrid catalysts benefits from the presence of a higher number of active sites and the abundant exposure of unsaturated S atoms rooted in the subnanometer structure, demonstrating a new class of subnanometer-scale catalysts.

Non-covalent surface modification of boron nitride nanotubes for enhanced catalysis.

Boron nitride nanotubes were functionalized with microperoxidase-11 in aqueous media, showing improved catalytic performance due to a strong electron coupling between the active centre of microperoxidase-11 and boron nitride nanotubes.

A Gaussian-3 theoretical study of the alkylthio radicals and their anions: structures, thermochemistry, and electron affinities.

The optimized geometries, electron affinities, and dissociation energies of the alkylthio radicals have been determined with the higher level of the Gaussian-3(G3) theory. The geometries are fully optimized and discussed. The reliable adiabatic electron affinities with ZPVE correction have been predicted to be 1.860 eV for the methylthio radical, 1.960 eV for the ethylthio radical, 1.980 and 2.074 eV for the two isomers (n-C3H7S and i-C3H7S) of the propylthio radical, 1.991, 2.133 and 2.013 eV for the three isomers (n-C4H9S, t-C4H9S, and i-C4H9S) of the butylthio radical, and 1.999, 2.147, 2.164, and 2.059 eV for the four isomers (n-C5H11S, b-C5H11S, c-C5H11S, and d-C5H11S) of the pentylthio radical, respectively. These corrected EAad values for the alkylthio radicals are in good agreement with available experiments, and the average absolute error of the G3 method is 0.041 eV. The dissociation energies of S atom from neutral CnH2n+1S (n = 1-5) and S(-) from corresponding anions CnH2n+1S(-) species have also been estimated respectively to examine their relative stabilities.

Structural insight into plant programmed cell death mediated by BAG proteins in Arabidopsis thaliana.

The recently identified plant Bcl-2-associated athanogene (BAG) family plays an extensive role in plant programmed cell death (PCD) processes ranging from growth and development to stress responses and even cell death. In the Arabidopsis thaliana BAG (AtBAG) protein family, four members (AtBAG1-4) have a domain organization similar to that of mammalian BAG proteins. Here, crystal structures of the BAG domains (BDs) of AtBAG1-4 have been determined; they have high homology and adopt a structure comprising three short parallel α-helices, similar to some mammalian BAG proteins. The crystal structure of a complex of the AtBAG1 ubiquitin-like domain and BAG domain (UBD) with the Hsc70 nucleotide-binding domain (NBD) was also determined. The binding of the AtBAG1 BD to the Hsc70 NBD induces conformational change of the Hsc70 NBD to the open state and reduces the affinity of the NBD for ADP. In vivo studies showed that bag2-1 mutant plants are larger than wild-type plants when growing under normal conditions, indicating that the AtBAG proteins might regulate plant PCD and confer tolerance to stresses in plants. These structural and functional analyses indicate that the AtBAG proteins function as nucleotide-exchange factors for Hsp70/Hsc70 in A. thaliana and that the mechanism of regulation of chaperone-mediated protein folding is conserved in plants.

[Principle of "multiple ecological niche of one-species (variety)" and its application in high yield cotton cultivation].

The multiple ecological niche of one-species (variety) (MENOS) population is formed by one species (variety), but the ecological units have different temporal, spatial, nutritional, temperature, or water ecological niche. The formation of MENOS population is characterized by its specific object, one species (variety), multiple layer canopy, human being's active adjustment, specific niche breadth, and overlap and separation of ecological units. This paper analyzed the characteristics of the super high yield cotton population with dual ecological niche of one-species (variety) (DENOS). As for the yield components, MENOS has the characteristics of high yield canopy and different yield plants.