Dissipation, residue and dietary risk assessment of difenoconazole in Rosa roxburghii.

Rosa roxburghii is a medicinal and edible plant, which is favored by consumers due to its rich vitamin C content. Residues and potential health risks of difenoconazole in the R. roxburghii ecosystem has aroused a concern considering its extensive use for controlling the powdery mildew of R. roxburghii. In this study, the residue of difenoconazole in R. roxburghii and soil was extracted by acetonitrile, purified by primary secondary amine and detected by liquid chromatography-tandem triple quadrupole mass spectrometry. The average recoveries in R. roxburghii and soil matrix varied from 82.59% to 99.63%, with relative standard deviations (RSD) of 1.14%-8.23%. The limit of quantification (LOQ) and detection (LOD) of difenoconazole in R. roxburghii and soil samples were 0.01 mg/kg. The dissipation of difenoconazole followed well the first-order kinetic, with a half-life of 3.99-5.57 d in R. roxburghii and 4.94-6.23 d in soil, respectively. And the terminal residues were <0.01-2.181 mg/kg and 0.014-2.406 mg/kg, respectively. The chronic and acute risk quotient values of difenoconazole were respectively 0.42% and 4.1%, which suggests that the risk was acceptable and safe to consumers. This study provides a reference for the safe and reasonable use of difenoconazole in R. roxburghii production.

Natural Product Aloesin Significantly Inhibits Spore Germination and Appressorium Formation in Magnaporthe oryzae.

This study aims to determine the effects of the natural product aloesin against Magnaporthe oryzae. The results exposed that aloesin had a high inhibitory effect on appressorium formation (the EC50 value was 175.26 µg/mL). Microscopic examination revealed that 92.30 ± 4.26% of M. oryzae spores could be broken down by 625.00 µg/mL of aloesin, and the formation rate of appressoria was 4.74 ± 1.00% after 12 h. M. oryzae mycelial growth was weaker than that on the control. The enzyme activity analysis results indicated that aloesin inhibited the activities of polyketolase (PKS), laccase (LAC), and chain-shortening catalytic enzyme (Aayg1), which are key enzymes in melanin synthesis. The inhibition rate by aloesin of PKS, LAC, and Aayg1 activity was 32.51%, 33.04%, and 43.38%, respectively. The proteomic analysis showed that actin expression was downregulated at 175.62 µg/mL of aloesin, which could reduce actin bundle formation and prevent the polar growth of hyphae in M. oryzae. This is the first report showing that aloesin effectively inhibits conidia morphology and appressorium formation in M. oryzae.

The Dissipation Kinetics, Residue Level and Dietary Risk of Kresoxim-Methyl in Rosa roxburghii and Soil Based on the QuEChERS Method Coupled with LC-MS/MS.

This study aimed to investigate the dissipation, residues and dietary assessment of kresoxim-methyl in the application of Rosa Roxburghii and soil field using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The results show that kresoxim-methyl in R. roxburghii samples was extracted by acetonitrile and purified by ethyl enediamine-N-propylsilane (PSA), while kresoxim-methyl in soil samples was extracted by acetonitrile and purified by octadecylsilyl solid phase dispersant (C18). 0.1% formic acid (v/v)-water-methanol solution was used as the mobile phase, LC-MS/MS exhibited a good linearity in the range of 0.001-10 mg L-1. The recoveries of R. roxburghii and soil matrix were 82.48%-102.55%, and the relative standard deviation (RSD) were 1.13%-4.21%. The limit of detection (LOD) and quantification (LOQ) of kresoxim-methyl in R. roxburghii and soil samples was 0.50 and 0.60 µg kg-1, respectively. The dissipation dynamics of kresoxim-methyl in R. roxburghii and soil followed the first-order kinetics, with the half-life of 4.28 and 4.41 days, respectively. The terminal residual amount of kresoxim-methyl in R. roxburghii and soil samples was 0.003-1.764 and 0.007-2.091 mg kg-1, respectively. The dietary intake risk assessment indicates that a risk quotient (RQ) for kresoxim-methyl based on the national estimated daily intake (NEDI) of 0.1995 mg was 0.79%, suggesting that the use of kresoxim-methyl on R. roxburghii at recommended dosage was safe to consumers. This study provides the theoretical basis for guiding the rational use of kresoxim-methyl in the production of R. roxburghii.

Visualization of the entire process of rice spikelet infection by Ustilaginoidea virens through nondestructive inoculation.

Introduction: Rice false smut caused by Ustilaginoidea virens, is a destructive fungal disease encountered in many rice-producing areas worldwide. To determine the process by which U. virens infects rice spikelets in the field. Methods: The green fluorescent protein-labeled U. virens was used as an inoculum to conduct artificial inoculation on rice at the booting stage via non-destructive panicle sheath instillation inoculation. Results: The results showed that the conidia of U. virens germinated on the surface of rice glumes and produced hyphae, which clustered at the mouth of rice glumes and entered the glumes through the gap between the palea and lemma. The conidia of U. virens colonized in rice floral organs, which led to pollen abortion of rice. U. virens wrapped the whole rice floral organ, and the floral organ-hyphae complex gradually expanded to open the glumes to form a rice false smut ball, which was two to three times larger than that observed in normal rice. Discussion: Panicle sheath instillation inoculation was shown to be a non-destructive inoculation method that could simulate the natural infection of U. virens in the field. The entire infection process of U. virens was visualized, providing a theoretical reference for formulating strategies to control rice false smut in the field.

Development of Simultaneous Determination Method of Pesticide High Toxic Metabolite 3,4-Dichloroaniline and 3,5 Dichloroaniline in Chives Using HPLC-MS/MS.

3,4-dichloroaniline (3,4-DCA) and 3,5-dichloroaniline (3,5-DCA) are, respectively, the primary metabolites deriving from the breakdown of phenylurea herbicides and dicarboximide fungicides in both soils and plants, whose residues in vegetable products have a heightened concern considering their higher health risks to humans and greater toxicity than the parent compounds in the environment. In this study, a sensitive high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was developed for the simultaneous determination of 3,4-DCA and 3,5-DCA residues in chive products based on the optimization of HPLC-MS/MS chromatographic and mass-spectrometric conditions using the standard substances and the modified QuEChERS preparation technique. The preparation efficiency of 3,4-DCA and 3,5-DCA from chive samples showed that acetonitrile was the best extractant. The combination of the purification agent graphite carbon black + primary secondary amine and the eluting agent acetonitrile + toluene (4:1, v/v) had a satisfactory purification effect. The linear correlation coefficients (R2) were more than 0.996 with the six concentration range of 0.001-1.000 mg/L for 3,4-DCA and 3,5-DCA. The limit of detection and limit of quantitation of this method was 0.6 and 2.0 µg/kg for 3,4-DCA, as well as 1.0 and 3.0 µg/kg for 3,5-DCA, respectively. The matrix effect range of 3,4-DCA and 3,5-DCA in chive tissues was from -9.0% to -2.6% and from -4.4% to 2.3%, respectively. The fortified recovery of 3,4-DCA and 3,5-DCA in chive samples at four spiked levels of 0.001-1.000 mg/kg was 75.3-86.0% and 78.2-98.1%, with the relative standard deviation of 2.1-8.5% and 1.4-11.9%, respectively. The limit of detection (LOD) and limit of quantification (LOQ) of the method were 0.6, 2.0, and 1.0, 3.03 for 4-DCA and 3,5-DCA, respectively. This study highlights that the analytical method established here can efficiently and sensitively detect residues of 3,4-DCA and 3,5-DCA residues for monitoring chive products. The method was successfully applied to 60 batches of actual vegetable samples from different regions.

Identification of the NAC Transcription Factor Family during Early Seed Development in Akebia trifoliata (Thunb.) Koidz.

This study aimed to gain an understanding of the possible function of NACs by examining their physicochemical properties, structure, chromosomal location, and expression. Being a family of plant-specific transcription factors, NAC (petunia no apical meristem and Arabidopsis thaliana ATAF1, ATAF2, and CUC2) is involved in plant growth and development. None of the NAC genes has been reported in Akebia trifoliata (Thunb.) Koidz (A. trifoliata). In this study, we identified 101 NAC proteins (AktNACs) in the A. trifoliata genome by bioinformatic analysis. One hundred one AktNACs were classified into the following twelve categories based on the phylogenetic analysis of NAC protein: NAC-a, NAC-b, NAC-c, NAC-d, NAC-e, NAC-f, NAC-g, NAC-h, NAC-i, NAC-j, NAC-k, and NAC-l. The accuracy of the clustering results was demonstrated based on the gene structure and conserved motif analysis of AktNACs. In addition, we identified 44 pairs of duplication genes, confirming the importance of purifying selection in the evolution of AktNACs. The morphology and microstructure of early A. trifoliata seed development showed that it mainly underwent rapid cell division, seed enlargement, embryo formation and endosperm development. We constructed AktNACs co-expression network and metabolite correlation network based on transcriptomic and metabolomic data of A. trifoliata seeds. The results of the co-expression network showed that 25 AtNAC genes were co-expressed with 233 transcription factors. Metabolite correlation analysis showed that 23 AktNACs were highly correlated with 28 upregulated metabolites. Additionally, 25 AktNACs and 235 transcription factors formed co-expression networks with 141 metabolites, based on correlation analysis involving AktNACs, transcription factors, and metabolites. Notably, AktNAC095 participates in the synthesis of 35 distinct metabolites. Eight of these metabolites, strongly correlated with AktNAC095, were upregulated during early seed development. These studies may provide insight into the evolution, possible function, and expression of AktNACs genes.

Recent Advances on Main Active Ingredients, Pharmacological Activities of Rosa roxbughii and Its Development and Utilization.

Rosa roxburghii tratt (R. roxburghii) is an important plant resource that is widely distributed in the southwest of China and favored by consumers due to its high nutritional value and healthy functions. Meanwhile, it is a traditional edible and medicinal plant in China. With the deepening research of R. roxburghii, more and more bioactive components and its health care and medicinal value have been discovered and developed in recent years. This review summarizes and discusses the recent advances on main active ingredients such as vitamin, protein, amino acid, superoxide dismutase, polysaccharide, polyphenol, flavonoid, triterpenoid and mineral, and pharmacological activities including antioxidant activity, immunomodulatory activity, anti-tumor activity, glucose and lipid metabolism regulation, anti-radiation effect, detoxification effect, and viscera protection of R. roxbughii, as well as its development and utilization. The research status and existing problems of R. roxburghii development and quality control are also briefly introduced. This review ends with some suggestions on the perspectives and directions for future research and potential applications of R. roxbughii.

Genome-Wide Identification and Expression Analysis of Rosa roxburghii Autophagy-Related Genes in Response to Top-Rot Disease.

Autophagy is a highly conserved process in eukaryotes that degrades and recycles damaged cells in plants and is involved in plant growth, development, senescence, and resistance to external stress. Top-rot disease (TRD) in Rosa roxburghii fruits caused by Colletotrichum fructicola often leads to huge yield losses. However, little information is available about the autophagy underlying the defense response to TRD. Here, we identified a total of 40 R. roxburghii autophagy-related genes (RrATGs), which were highly homologous to Arabidopsis thaliana ATGs. Transcriptomic data show that RrATGs were involved in the development and ripening processes of R. roxburghii fruits. Gene expression patterns in fruits with different degrees of TRD occurrence suggest that several members of the RrATGs family responded to TRD, of which RrATG18e was significantly up-regulated at the initial infection stage of C. fructicola. Furthermore, exogenous calcium (Ca2+) significantly promoted the mRNA accumulation of RrATG18e and fruit resistance to TRD, suggesting that this gene might be involved in the calcium-mediated TRD defense response. This study provided a better understanding of R. roxburghii autophagy-related genes and their potential roles in disease resistance.

Bacillus cereus WL08 immobilized on tobacco stem charcoal eliminates butylated hydroxytoluene in soils and alleviates the continuous cropping obstacle of Pinellia ternata.

Butylated hydroxytoluene (BHT), as an emerging contaminant in ecosystems, has potential influences on animals, aquatic organisms, and public health, and has been proven to be a major allelochemical of Pinellia ternata. In this study, Bacillus cereus WL08 was used to rapidly degrade BHT in liquid culture. Strain WL08 immobilized on tobacco stem charcoal (TSC) particles notably accelerated BHT removal in contract to its free cells, and exhibited excellent reutilization and storage capacities. The optimal removal parameters of TSC WL08 were ascertained to be pH 7.0, 30 °C, 50 mg L-1 BHT and 0.14 mg L-1 TSC WL08. Moreover, TSC WL08 significantly accelerated the degradation of 50 mg L-1 BHT in sterile and non-sterile soils compared to that of free WL08 or natural dissipation, and notably shortened their half-lives by 2.47- or 362.14- fold, and 2.20- or 14.99- fold, respectively. Simultaneously, TSC WL08 was introduced into the continuous cropping soils of P. ternata, which accelerated the elimination of allelochemical BHT, and notably enhanced the photosynthesis, growth, yield, and quality of P. ternata. This study provides new insights and strategies for the rapid in situ remediation of BHT-polluted soils and effective alleviation of P. ternata cropping obstacles.

Distribution of Emamectin Benzoate Granules in Maize Plants by Broadcasting into Maize Leaf Whorls.

Good control effects on fall armyworm (FAW) can be obtained by broadcasting emamectin benzoate (EB) granules into maize leaf whorls. However, the distribution of EB in maize plants is not clear. In this study, EB granules were prepared by the rotating granulation method, and the granules were characterized using a Fourier transform infrared spectrometer. The behavior of EB granules in water was observed using a microscope, and in vitro release of EB from granules was also studied. A method for the determination of EB in maize plants, old leaves, grains, and cobs was established by using ultra-performance liquid chromatography-tandem mass spectrometry. The results showed that EB was loaded in granules successfully, and the granules disintegrated slowly in water, so the release of granules could be regulated using various water contents. The prepared EB granules were qualified and stable. The field experiment showed that the concentration of EB in maize leaf whorls could be maintained above 0.23 mg·kg-1 within 3 days after broadcasting EB granules. This ensured that FAW could be killed in a short time. Then, EB gradually transferred to the old leaves. After 21 days of application, the content of EB in the old leaves was 0.07 mg·kg-1, which has long-time control effects on FAW. The control effects of the three doses of granules against Spodoptera frugiperda were higher than 78% after 14 days of application. At the tested dosage, no phytotoxicity to crops was observed. At harvest, neither the maize grain nor the cobs had EB content. New controlled formulations to S. frugiperda were developed and will be suitable for application in mountainous areas where the lack of water resources is a factor.

Impact Buffering Characteristics of One-Dimensional Elastic-Plastic Composite Granular Chain.

Considering the elastic-plastic deformation, the wave propagations and energy transmissions of the one-dimensional three-segment composite granular chain are studied. The axial symmetry model for elastic-perfectly plastic materials is built by using the finite element method. Six materials with different yield strengths are selected for the adjustable segment. The results show that the repeated loading and unloading behaviors, as well as the wave propagations in the elastic-plastic granular chain, are complex and significantly different from those in the purely elastic granular chain. The yield strength of the granular materials in the adjustable segment has significant effects on energy dissipation and wave velocity, which could be used to design the impact buffer. The studies show that taking lower yield strength for the adjustable part than the non-adjustable part, the energy dissipation could be increased, and the wave velocity could be reduced, then the arrival time of the impact waves could be delayed. These characteristics of the elastic-plastic granular chain could be used to design metamaterials for impact absorbers in impact protection.

Association of Physcion and Chitosan Can Efficiently Control Powdery Mildew in Rosa roxburghii.

Powdery mildew is an extremely serious disease of all Rosa roxburghii production regions in China and frequently causes 30~40% of economic losses. Natural products are considered excellent alternatives to chemical fungicides. In this work, we investigated the efficacy of physcion used together with chitosan controls R. roxburghii powdery mildew and impacts its resistance, growth, yield, and quality. The results reveal that the foliar application of 12.5 mg L−1 0.5% physcion aqueous solutions (AS) + 250 mg L−1 chitosan efficiently controlled powdery mildew with the efficacies of 92.65% and 90.68% after 7 d and 14 d, respectively, which conspicuously (p < 0.05) higher than 83.62% and 80.43% of 25 mg L−1 0.5% physcion AS, as well as 70.75% and 77.80% of 500 mg L−1 chitosan. Meanwhile, this association prominently ameliorated the resistant and photosynthetic capabilities of R. roxburghii. Simultaneously, this association was more efficient than physcion or chitosan alone for ameliorating the yield and quality of R. roxburghii. This work emphasizes that the association of physcion and chitosan can be nominated as a natural, efficient and environmental-friendly alternative ingredient in controlling R. roxburghii powdery mildew and ameliorating its resistant, photosynthesis, yield, and quality.

Chitosan as an Adjuvant to Enhance the Control Efficacy of Low-Dosage Pyraclostrobin against Powdery Mildew of Rosa roxburghii and Improve Its Photosynthesis, Yield, and Quality.

Powdery mildew is the most serious fungal disease of Rosa roxburghii in Guizhou Province, China. In this study, the control role of chitosan-assisted pyraclostrobin against powdery mildew of R. roxburghii and its influences on the resistance, photosynthesis, yield, quality and amino acids of R. roxburghii were evaluated. The results indicate that the foliar application of 30% pyraclostrobin suspension concentrate (SC) 100 mg L−1 + chitosan 500 mg L−1 displayed a superior control potential against powdery mildew, with a control efficacy of 89.30% and 94.58% after 7 d and 14 d of spraying, respectively, which significantly (p < 0.01) exceeded those of 30% pyraclostrobin SC 150 mg L−1, 30% pyraclostrobin SC 100 mg L−1, and chitosan 500 mg L−1. Simultaneously, their co-application could effectively enhance their effect on the resistance and photosynthesis of R. roxburghii leaves compared to their application alone. Meanwhile, their co-application could also more effectively enhance the yield, quality, and amino acids of R. roxburghii fruits compared to their application alone. This work highlights that chitosan can be applied as an effective adjuvant to promote the efficacy of low-dosage pyraclostrobin against powdery mildew in R. roxburghii and improve its resistance, photosynthesis, yield, quality, and amino acids.

Safety Evaluation of Heavy Metal Contamination and Pesticide Residues in Coix Seeds in Guizhou Province, China.

The coix seed is a medicinal and edible plant with rich nutritional and medicinal values. With the expansion of the coix seed consumption market, the problem of coix seed safety has attracted attention worldwide. The aims of this work were to evaluate the contamination of mercury (Hg), lead (Pb), cadmium (Cd), arsenic (As), chromium (Cr) and 116 pesticides in coix seeds collected from 12 main producing regions of coix seeds in the Guizhou Province of China and to analyze the major contributors of heavy metal and pesticide contamination in coix seed. The results show that the average contents of Pb, Cd, As and Cr in the 123 coix seed samples were 0.0069, 0.0021, 0.0138 and 0.1107 mg/kg, respectively, while Hg was not detected in all coix seed samples. Among the five heavy metals detected, only the Cr contents of three samples were found to be higher than the contaminant limit of Chinese standard GB2762-2017 (CSGB). A total of 13 pesticides were detected in 29 samples from seven main production regions of coix seeds, accounting for 23.6% of all the samples. The detection rates of chlorpyrifos were the highest (8.13%), followed by fenpropathrin (4.06%), bifenthrin (2.43%) and phoxim (1.62%), while the detection rates of the remaining pesticides were below 1%. Moreover, the residual risk score of dichlorvos was the highest of all the pesticides detected. The pollution index and risk assessment of heavy metals and pesticide residues indicates that coix seeds were at safe levels for consumption. In the production process of coix seeds, the local government should control the soil in areas heavily polluted by heavy metals and strengthen the monitoring and guidance on the scientific and rational use of pesticides.

Spatio-Temporal Variation in the Phyllospheric Microbial Biodiversity of Alternaria Alternata-Infected Tobacco Foliage.

Phyllospheric microbial composition of tobacco (Nicotiana tabacum L.) is contingent upon certain factors, such as the growth stage of the plant, leaf position, and cultivar and its geographical location, which influence, either directly or indirectly, the growth, overall health, and production of the tobacco plant. To better understand the spatiotemporal variation of the community and the divergence of phyllospheric microflora, procured from healthy and diseased tobacco leaves infected by Alternaria alternata, the current study employed microbe culturing, high-throughput technique, and BIOLOG ECO. Microbe culturing resulted in the isolation of 153 culturable fungal isolates belonging to 33 genera and 99 bacterial isolates belonging to 15 genera. High-throughput sequencing revealed that the phyllosphere of tobacco was dominantly colonized by Ascomycota and Proteobacteria, whereas, the most abundant fungal and bacterial genera were Alternaria and Pseudomonas. The relative abundance of Alternaria increased in the upper and middle healthy groups from the first collection time to the third, whereas, the relative abundance of Pseudomonas, Sphingomonas, and Methylobacterium from the same positions increased during gradual leaf aging. Non-metric multi-dimensional scaling (NMDs) showed clustering of fungal communities in healthy samples, while bacterial communities of all diseased and healthy groups were found scattered. FUNGuild analysis, from the first collection stage to the third one in both groups, indicated an increase in the relative abundance of Pathotroph-Saprotroph, Pathotroph-Saprotroph-Symbiotroph, and Pathotroph-Symbiotroph. Inclusive of all samples, as per the PICRUSt analysis, the predominant pathway was metabolism function accounting for 50.03%. The average values of omnilog units (OUs) showed relatively higher utilization rates of carbon sources by the microbial flora of healthy leaves. According to the analysis of genus abundances, leaf growth and leaf position were the important drivers of change in structuring the microbial communities. The current findings revealed the complex ecological dynamics that occur in the phyllospheric microbial communities over the course of a spatiotemporal varying environment with the development of tobacco brown spots, highlighting the importance of community succession.

Molecular Characterization of a Novel Polerovirus Infecting Soybean in China.

Poleroviruses are positive-sense, single-stranded viruses. In this study, we describe the identification of a novel polerovirus isolated from soybean displaying curled leaves. The complete viral genome sequence was identified using high-throughput sequencing and confirmed using rapid amplification of cDNA ends (RACE), RT-PCR and Sanger sequencing. Its genome organization is typical of the members of genus Polerovirus, containing seven putative open reading frames (ORFs). The full genome is composed of single-stranded RNA of 5822 nucleotides in length, with the highest nucleotide sequence identity (79.07% with 63% coverage) for cowpea polerovirus 2 (CPPV2). Amino acid sequence identities of the protein products between the virus and its relatives are below the threshold determined by the International Committee of Taxonomy of Viruses (ICTV) for species demarcation, and this strongly supports this virus' status as a novel species, for which the name soybean chlorotic leafroll virus (SbCLRV) is proposed. Recombination analysis identified a recombination event in the ORF5 of the 3' portion in the genome. Phylogenetic analyses of the genome and encoded protein sequences revealed that the new virus is closely related to phasey bean mild yellows virus, CPPV2 and siratro latent polerovirus. Subsequently, we demonstrated the infectivity of SbCLRV in Nicotiana benthamiana via infectious cDNA clone generation and agroinoculation.

Co-Application of Tetramycin and Chitosan in Controlling Leaf Spot Disease of Kiwifruit and Enhancing Its Resistance, Photosynthesis, Quality and Amino Acids.

Leaf spot disease caused by Lasiodiplodia theobromae and Alternaria tenuissima is a seriously fungal disease in kiwifruit production. In this study, the co-application of tetramycin and chitosan against leaf spot disease in kiwifruit and its effects on the disease resistance, photosynthesis, quality and amino acids of kiwifruit were investigated. The results show that tetramycin exhibited an excellent antifungal activity against L. theobromae and A. tenuissima with EC50 values of 2.37 and 0.16 mg kg−1. In the field, the foliar co-application of tetramycin and chitosan could effectively control leaf spot disease with control efficacy of 89.44% by spraying 0.3% tetramycin aqueous solutions (AS) 5000 time liquid + chitosan 100 time liquid, which was significantly (ANOVA, p < 0.01) higher than 79.80% of 0.3% tetramycin AS 5000 time liquid and 56.61% of chitosan 100 time liquid. Simultaneously, the co-application of tetramycin and chitosan was more effective than tetramycin or chitosan alone in enhancing the disease resistance and photosynthesis of kiwifruit leaves, as well as improving the quality and amino acids of kiwifruit fruits. This work highlights that chitosan is a practicable, cost-effective and eco-friendly adjuvant of tetramycin for controlling leaf spot disease of kiwifruit, enhancing resistance and photosynthesis of leaves and improving quality and amino acids of fruits.

Dissipation and Residues of Pyraclostrobin in Rosa roxburghii and Soil under Filed Conditions.

Rosa roxburghii has been widely planted in China. Powdery mildew is the most serious disease of R. roxburghii cultivation. Pyraclostrobin was widely used as a novel fungicide to control powdery mildew of R. roxburghii. To assess the safety of pyraclostrobin for use on R. roxburghii fruits, its residue rapid analysis as well as an investigation on its dissipation behaviors and terminal residues in R. roxburghii and soil under field conditions were carried out. The QuEChERS method was simplified using LC−MS/MS detection and combined with liquid−liquid extraction purification to allow determination of pyraclostrobin levels in R. roxburghii fruits and the soil. The fortified recoveries at 0.1~5.0 mg/kg were 93.48~102.48%, with the relative standard deviation of 0.64~3.21%. The limit of detection of the analytical method was 0.16 and 0.15 µg/kg for R. roxburghii fruit and soil, respectively. The effects of different spray equipment and formulations on the persistence of pyraclostrobin in R.roxburghii were as follows: gaston gasoline piggyback agricultural sprayer (5.38 d) > manual agricultural backpack sprayer (3.37 d) > knapsack multi-function electric sprayer (2.91 d), suspension concentrate (SC) (6.78 d) > wettable powder (WP) (5.64 d) > water dispersible granule (WG) (4.69 d). The degradation of pyraclostrobin followed the first-order kinetics and its half-lives in R.roxburghii and soil were 6.20~7.79 days and 3.86~5.95 days, respectively. The terminal residues of pyraclostrobin in R. roxburghii and soil were 0.169~1.236 mg/kg and 0.105~3.153 mg/kg, respectively. This study provides data for the establishment of the maximum residue limit (MRL) as well as the safe and rational use of pyraclostrobin in R. roxburghii production.

Comparative Analysis of Fruit Metabolome Using Widely Targeted Metabolomics Reveals Nutritional Characteristics of Different Rosa roxburghii Genotypes.

The fruits of Rosa roxburghii (R. roxburghii) Tratt., which are rich in bioactive compounds, provide numerous health benefits, yet the overall metabolism of R. roxburghii fruits and the metabolic profiles among different genotypes of R. roxburghii fruits are not fully understood. In the research, we used ultra-performance liquid chromatography/tandem mass spectrometry analysis to identify and quantify metabolites including phenolic acids, amino acids, and organic acids in six R. roxburghii genotypes; a total of 723 metabolites were identified. Comparative analysis showed some different characteristic metabolites in each genotype. Moreover, flavonoids, triterpenoids, and phenolic acids were significantly correlated with the antioxidant capacity of the fruit extract. Our results suggest that R. roxburghii fruits have rich bioactive metabolites beneficial to human health and that Rr-7 and Rr-f have more potential to be used as medicinal material or functional food than other genotypes. This research provides helpful information for developing new functional foods of R. roxburghii genotypes.

Lauric Acid Induces Apoptosis of Rice Sheath Blight Disease Caused by Rhizoctonia solani by Affecting Fungal Fatty Acid Metabolism and Destroying the Dynamic Equilibrium of Reactive Oxygen Species.

Rice sheath blight, caused by Rhizoctonia solani, is one of the major rice diseases. In order to better understand the inhibitory mechanism of lauric acid on the disease, RNA sequencing (RNA-Seq) was used to analyze the transcriptome changes in Rhizoctonia solani treated with lauric acid for 3 h, 6 h, 18 h, and 24 h, including 2306 genes; 1994 genes; 2778 genes; and 2872 genes. Based on gene ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses, we found that protein processing in endoplasmic reticulum (KO04141), carbon metabolism (KO01200), and starch and sucrose metabolism were significantly enriched. Most oxidoreductase, dehydrogenase, reductase, and transferase genes are downregulated in this process. Lauric acid can affect ergosterol content, mitochondrial membrane potential collapse, hydrogen peroxide content, electrolyte leakage, reactive oxygen species balance, and can induce endoplasmic reticulum (ER) stress. Lauric acid also increased the expression levels of ER chaperone glucose regulatory protein Grp78 (BIP), protein disulfide isomerase (PDI), and Calpain (CNX), and decreased the expression levels of HSP40, HSP70, and HSP90 genes. Lauric acid affected the ergosterol content in the cell membrane of R. solani, which induces ER stress and increases the BiP level to induce the apoptosis of Rhizoctonia solani. These results indicated that lauric acid could be used to control rice sheath blight.