Salicylic acid inhibits rice endocytic protein trafficking mediated by OsPIN3t and clathrin to affect root growth.

Salicylic acid (SA) plays important roles in different aspects of plant development, including root growth, where auxin is also a major player by means of its asymmetric distribution. However, the mechanism underlying the effect of SA on the development of rice roots remains poorly understood. Here, we show that SA inhibits rice root growth by interfering with auxin transport associated with the OsPIN3t- and clathrin-mediated gene regulatory network (GRN). SA inhibits root growth as well as Brefeldin A-sensitive trafficking through a non-canonical SA signaling mechanism. Transcriptome analysis of rice seedlings treated with SA revealed that the OsPIN3t auxin transporter is at the center of a GRN involving the coat protein clathrin. The root growth and endocytic trafficking in both the pin3t and clathrin heavy chain mutants were SA insensitivity. SA inhibitory effect on the endocytosis of OsPIN3t was dependent on clathrin; however, the root growth and endocytic trafficking mediated by tyrphostin A23 (TyrA23) were independent of the pin3t mutant under SA treatment. These data reveal that SA affects rice root growth through the convergence of transcriptional and non-SA signaling mechanisms involving OsPIN3t-mediated auxin transport and clathrin-mediated trafficking as key components.

Assessing the biodiversity of rhizosphere and endophytic fungi in Knoxia valerianoides under continuous cropping conditions.

BACKGROUND: Rhizosphere and endophytic fungi play important roles in plant health and crop productivity. However, their community dynamics during the continuous cropping of Knoxia valerianoides have rarely been reported. K. valerianoides is a perennial herb of the family Rubiaceae and has been used in herbal medicines for ages. Here, we used high-throughput sequencing technology Illumina MiSeq to study the structural and functional dynamics of the rhizosphere and endophytic fungi of K. valerianoides. RESULTS: The findings indicate that continuous planting has led to an increase in the richness and diversity of rhizosphere fungi, while concomitantly resulting in a decrease in the richness and diversity of root fungi. The diversity of endophytic fungal communities in roots was lower than that of the rhizosphere fungi. Ascomycota and Basidiomycota were the dominant phyla detected during the continuous cropping of K. valerianoides. In addition, we found that root rot directly affected the structure and diversity of fungal communities in the rhizosphere and the roots of K. valerianoides. Consequently, both the rhizosphere and endophyte fungal communities of root rot-infected plants showed higher richness than the healthy plants. The relative abundance of Fusarium in two and three years old root rot-infected plants was significantly higher than the control, indicating that continuous planting negatively affected the health of K. valerianoides plants. Decision Curve Analysis showed that soil pH, organic matter (OM), available K, total K, soil sucrase (S_SC), soil catalase (S_CAT), and soil cellulase (S_CL) were significantly related (p < 0.05) to the fungal community dynamics. CONCLUSIONS: The diversity of fungal species in the rhizosphere and root of K. valerianoides was reported for the first time. The fungal diversity of rhizosphere soil was higher than that of root endophytic fungi. The fungal diversity of root rot plants was higher than that of healthy plants. Soil pH, OM, available K, total K, S_CAT, S_SC, and S_CL were significantly related to the fungal diversity. The occurrence of root rot had an effect on the community structure and diversity of rhizosphere and root endophytic fungi.

Streptomyces beigongshangae sp. nov., isolated from baijiu fermented grains, could transform ginsenosides of Panax notoginseng.

A Gram-stain-positive actinomycete, designated REN17T, was isolated from fermented grains of Baijiu collected from Sichuan, PR China. It exhibited branched substrate mycelia and a sparse aerial mycelium. The optimal growth conditions for REN17T were determined to be 28 °C and pH 7, with a NaCl concentration of 0 % (w/v). ll-Diaminopimelic acid was the diagnostic amino acid of the cell-wall peptidoglycan and the polar lipids were composed of phosphatidylethanolamine, phosphatidylinositol, an unidentified phospholipid, two unidentified lipids and four unidentified glycolipids. The predominant menaquinone was MK-9 (H2), MK-9 (H4), MK-9 (H6) and MK-9 (H8). The major fatty acids were iso-C16 : 0. The 16S rRNA sequence of REN17T was most closely related to those of Streptomyces apricus SUN 51T (99.8 %), Streptomyces liliiviolaceus BH-SS-21T (99.6 %) and Streptomyces umbirnus JCM 4521T (98.9 %). The digital DNA-DNA hybridization, average nucleotide identity and average amino acid identify values between REN17T and its closest replated strain, of S. apricus SUN 51T, were 35.9, 88.9 and 87.3 %, respectively. Therefore, REN17T represents a novel species within the genus Streptomyces, for which the name Streptomyces beigongshangae sp. nov. is proposed. The type strain is REN17T (=GDMCC 4.193T=JCM 34712T). While exploring the function of the strain, REN17T was found to possess the ability to transform major ginsenosides of Panax notoginseng (Burk.) F.H. Chen (Araliaceae) into minor ginsenoside through HPLC separation, which was due to the presence of ß-glucosidase. The recombinant ß-glucosidase was constructed and purified, which could produce minor ginsenosides of Rg3 and C-K. Finally, the enzymatic properties were characterized.

Twisted Structure Induced Solid-State Fluorescence and Room-Temperature Phosphorescence from Furan-Based Carbon Dots.

Boron doping can effectively induce solid-state fluorescence (SSF) in carbon dots (CDs); however, research on the intrinsic mechanism underlying this phenomenon is lacking. Herein, a design strategy for boron-doped furan-based CDs is proposed, CDs with aggregation-induced emission (AIE) properties are synthesized, and the mechanism by which boron atom dopants induces SSF and room-temperature phosphorescence (RTP) is elucidated. The morphology and structural characterization of the CDs indicate that boron doping leads to structural twisting of the CDs. The AIE phenomenon of CDs arises from the inhibition of the twisted structure motions and a reduction in the nonradiative relaxation rate during the aggregation process. In addition, CDs with twisted structures exhibit a smaller overlap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), effectively reducing the singlet-triplet splitting energy (ΔEST). CDs embedded in microcrystalline cellulose (MCC) exhibit green RTP because the nonradiative transitions are suppressed, and the excited triplet species remain stable. For the first time, this study reveals the structure-activity relationship between the twisted structure and optical properties of CDs, providing a new approach for the preparation of solid-state light-emitting CDs.

First Report of the Root-Knot Nematode Meloidogyne incognita on Bletilla striata Rchb.f. (Orchidaceae) in China.

Bletilla striata Rchb.f., is a perennial herbaceous bulbous plant known as the Chinese ground or hyacinth orchid classified in the Orchidaceae. It is native to southeast Asia and mainly distributed in China, Japan and northern Myanmar (He et al. 2017). It has the functions of astringent hemostasis and analgesia, and can also be used to treat traumatic bleeding, ulcers, swelling and chapped skin. Therefore, it occupies an important position in traditional Chinese medicine (Xu et al. 2019). In June 2023, three farmers in Mengzi (103.39°N, 23.21°E), Yunnan Province, China, observed that some Bletilla striata Rchb.f. plants grew poorly with small and chlorotic leaves (Figure 1 A). We suspected that these symptoms were caused by root-knot nematode infection, but the galls on the roots were small and inconspicuous (Figure 1 A). The presence of nematode females in both the galled regions and the normal roots (Figure 1 B), revealed by fuchsin staining (Byrd et al. 1983), indicated that the symptoms were probably caused by root-knot nematode infection. To estimate the incidence rates, we randomly selected 100 B. striata Rchb.f. plants from each of five fields representing a total area of 3000 m2. In these fields, the occurrence of stained root-knot nematodes were 19.3%, 17%, 18.3%, 15%, and 13%, respectively. The gall rating of the infected plants in the B striata Rchb.f. samples collected from the five fields was 2 (rating scale of 0 to 5). Females (n=20), second-stage juveniles (J2s, n=20) and egg masses (n=20) were extracted and collected from roots and soil for morphological and molecular identification. The females had a white, pyriform body and their perineal patterns exhibited a high and square dorsal arch, lacking distinct lateral line (Figure 1. C & D). Measurements of females (n = 20) were: body length (BL) = 708.64±89.6 µm (554.36 to 844.51 µm); maximum body width (BW) = 461.73±47.44 µm (365.25 to 561.49 µm); stylet length (ST) = 15.49±3.15 µm (10.55 to 19.78 µm); and distance from dorsal esophageal gland opening to the stylet knobs (DGO) = 3.33±0.27 µm (2.77 to 3.93 µm). Measurements of J2s (n=20) were BL = 417.7±47.67 µm (342.16 to 499.68 µm); BW = 15.74±2.66 µm (11.05 to 25.63 µm); ST = 12.49±1.12 µm (10.19 to 15.02 µm); DGO = 2.64±0.59 µm (40.17 to 68.74 µm); tail length = 51.93±8.55 µm (10.43 to 27.22 µm); hyaline tail terminus = 18.23±3.99 µm (1.48 to 3.98 µm). These morphological features match the description of Meloidogyne incognita (Eisenback et al. 1981). To further confirm the species, we selected three infected plants from each field for molecular identification, the ITS region amplified using the primers 18S/26S (5'-TTGATTACGTCCCTGCCCTTT-3',5'-TTTCACTCGCCGTTACTAAGG-3') (Vrain et al. 1992) . A 729 bp PCR product of ITS region (accession nos. OR463907) was obtained from all infected plants. The amplicons from 18S/26S primer pair were sequenced and the sequences showed 95.29% homology with sequences of M. incognita (accession nos. MT209948.1). Moreover, a 835 bp DNA fragment (accession nos. OR469000) was obtained using the specific primers Mi-F/Mi-R (5'-GTGAGGATTCAGCTCCCCAG-3',5'-ACGAGGAACATACTTCTCCGTCC-3') for M. incognita (Meng et al. 2004), the sequence showed 99.28% homology with sequences of M. incognita (accession nos. ON416569). The morphological features and molecular data confirmed the identification of the root-knot nematode on B. striata Rchb.f. as M. incognita. To confirm the pathogenicity, ten healthy B. striata Rchb.f. seedlings were each inoculated with 500 freshly hatched J2s isolated from field Bletilla striata Rchb.f.. Five healthy seedlings without J2 inoculation were used as controls. At 60 days after inoculation, most of the inoculated plants exhibited similar symptoms to those initially observed by farmers in the field. On average, 1532 J2s were recovered from each inoculated plant, yielding a reproductive factor of 2.1. The gall rating for these inoculated plants was 2. Fuchsin staining revealed the presence of root-knot nematode females within the roots, with an average of 17 females detected per inoculated plant. No symptoms were observed in the control plants. This is the first report of M. incognita infecting B. striata Rchb.f. in China. M. incognita can cause severe infection and damage to some crops, resulting in serious economic losses (Eisenback, 2022). The growers need to take measures to prevent the spread of this nematode.

EGFR-Targeted Liposomes Combined with Ginsenoside Rh2 Inhibit Triple-Negative Breast Cancer Growth and Metastasis.

Triple-negative breast cancer (TNBC) remains the most challenging breast cancer subtype due to its lack of targeted therapies and poor prognosis. In order to treat patients with these tumors, efforts have been made to explore feasible targets. Epidermal growth factor receptor (EGFR)-targeted therapy is currently in clinical trials and regarded to be a promising treatment strategy. In this study, an EGFR-targeting nanoliposome (LTL@Rh2@Lipo-GE11) using ginsenoside Rh2 as a wall material was developed, in which GE11 was used as the EGFR-binding peptide to deliver more ginsenoside Rh2 and luteolin into TNBC. In comparison to non-targeted liposomes (Rh2@Lipo and LTL@Rh2@Lipo), the nanoliposomes LTL@Rh2@Lipo-GE11 demonstrated a high specificity to MDA-MB-231 cells that expressed a high level of EGFR both in vitro and in vivo, contributing to the strong inhibitory effects on the growth and migration of TNBC. These results suggest that LTL@Rh2@Lipo-GE11 is a prospective candidate for targeted therapy of TNBC, with a remarkable capability to inhibit tumor development and metastasis.

Evolution of the rice blast pathogen on spatially structured rice landraces maintains multiple generalist fungal lineages.

Traditional agrosystems, where humans, crops and microbes have coevolved over long periods, can serve as models to understand the ecoevolutionary determinants of disease dynamics and help the engineering of durably resistant agrosystems. Here, we investigated the genetic and phenotypic relationship between rice (Oryza sativa) landraces and their rice blast pathogen (Pyricularia oryzae) in the traditional Yuanyang terraces of flooded rice paddies in China, where rice landraces have been grown and bred over centuries without significant disease outbreaks. Analyses of genetic subdivision revealed that indica rice plants clustered according to landrace names. Three new diverse lineages of rice blast specific to the Yuanyang terraces coexisted with lineages previously detected at the worldwide scale. Population subdivision in the pathogen population did not mirror pattern of population subdivision in the host. Measuring the pathogenicity of rice blast isolates on landraces revealed generalist life history traits. Our results suggest that the implementation of disease control strategies based on the emergence or maintenance of a generalist lifestyle in pathogens may sustainably reduce the burden of disease in crops.

First Report of Penicillium subrubescens Causing Root Rot of Knoxia roxburghii in China.

Knoxia roxburghii (syn. Knoxia valerianoides), locally known as 'Zi Daji', is a perennial herb that belongs to the Rubiaceae family, cultivated in different areas of China and recognized for its medicinal properties in traditional Chinese medicine (Chen et al. 2022). In 2021, root rot was observed during summer on K. roxburghii in Xiangyun and Dali, Yunnan Province (25°25'N, 100°40'E), China. Root rots were characterized by dark brown tissue from stem base to root, loss of vitality in tender leaves and wither. Three symptomatic root samples of K. roxburghii collected from different fields were rinsed with running water, and 0.5-1 cm2 fragments of diseased tissues were cut and surface-disinfested with 75% ethanol for 30 s, and 1% NaClO for 180 s. The fragments were then washed with sterile water, transferred to potato dextrose agar (PDA, 4.6%) and incubated at 28℃ in the dark for 3 days. A total of 13 isolates with consistent appearances were obtained by single spore isolation. These colonies on PDA showed gray and light brown obverse, and light green reverse after 10 days. The average growth rate was 3 mm per day. Conidia were nearly spherical or broadly elliptic, greyish-green, and 1.4-2.4×1.3-2.2 µm in size (n=50). The conidiophore has symmetrical or asymmetrical broom branches from the tip, with 2-4 small stems. The conidiophore branching patterns were predominantly biverticillate; stipes coarsely roughened, 80-210×2.6-3.0 µm; metulae were usually appressed verticils of 3-6, 6.4-12.5×1.6-3.0 µm; phialides were short and wide neck, 3.8-4.8×1.1-1.8 µm (n=30). The morphological characteristics of the fungus were identical to Penicillium (Mansouri et al. 2013). To further identify the isolate, one isolate (ByF10) was randomly selected for identification. DNA was extracted from mycelia using a simplified CTAB method. Primer pairs, ITS1/ITS4 and Bt2a/Bt2b were used to amplify the partial regions of rDNA internal transcribed spacer (ITS) and ß-tubulin (TUB), respectively (White et al. 1990; Glass and Donaldson 1999). Blast searches showed that the sequences of ITS (OQ954757) and TUB (OQ970059) of isolate ByF10 were 99% (MH865456) and 100% (KC797611) identical with P. subrubescens CBS 130205 and CBS 129617, respectively. A concatenated phylogenetic tree (ITS+TUB) constructed using the maximum likelihood method showed that ByF10 was closely grouped next to isolates of P. subrubescens. Pathogenicity test was carried out using 1-year-old healthy seedlings of K. roxburghii cv. Yunji-1 growing on autoclaved soil (n=10). Ten plants were inoculated with mycelial blocks (5 mm2), which were taken from the colony margins of a 10-day-old culture (PDA) colony, and placed on the roots near the soil. Five control plants were inoculated with non-colonized PDA plugs. The pathogenicity test was repeated three times. All plants were kept at 25℃, 70% relative air humidity, and 12 h light/12 h regime dark for 35 days. After that period 95% of inoculated plants showed typical symptoms of root browning. P. subrubescens was only re-isolated from the inoculated plants, and identified based on morphological and molecular characteristics. No symptoms were observed in the controls. To the best of our knowledge, this is the first report of P. subrubescens causing root rot on K. roxburghii in China and the world.

Characterization of a Root-Knot Nematode Infecting Aconitum carmichaelii in Southwest China.

Growth of the Chinese herbal medicine industry has resulted in several new pests and diseases. China is one of the world largest producers of monkshood (Aconitum carmichaelii Debx.), but an unidentified root-knot nematode has become a significant pest in the southwestern provinces of Yunnan and Sichuan. Morphological characteristics and the ribosomal DNA-internal transcribed spacer and D2-D3 region of the 28S ribosomal RNA gene sequences were used to identify the nematode as Meloidogyne hapla. Through investigation, this is the first report of M. hapla infecting monkshood in Yunnan and Sichuan Provinces.

A new Panax notoginseng Leaf Spot Caused by Boeremia linicola in Yunnan, China.

Panax notoginseng-also known as Tianqi and Sanqi-is one of the most highly valued medicinal perennial herbs in the world (Wang et al. 2016). In August 2021, leaf spot was observed on P. notoginseng leaves in Lincang sanqi base (23º43´10˝N, 100º7´32˝E, 13.33 hm2). Symptoms expanded from water soaked areas on the leaves to form irregular round or oval leaf spots with transparent or grayish-brown centers containing black granular matter, with an incidence of 10 to 20%. To identify the causal agent, ten symptomatic leaves were randomly selected from ten P. notoginseng plants. Symptomatic leaves were cut into small pieces (5 mm2) with asymptomatic tissue margins, disinfected in 75% ethanol for 30s and in 2% sodium hypochlorite for 3 min, and rinsed three times with sterile distilled water. The tissue portions were placed on potato dextrose agar (PDA) plates incubated at 20℃ with a 12 h light/dark photoperiod. Seven pure isolates were obtained with similar colony morphology, dark gray (top view) or taupe (back view) coloration, with flat and villous surfaces. Pycnidia were globose to subglobose, glabrous or with few mycelial outgrowths, dark brown to black, 22.46 to 155.94 (av. 69.57) µm × 18.20 to 130.5 (av. 57.65) µm (n=50) in size. Conidia were ellipsoidal to cylindrical, thinwalled, smooth, hyaline, aseptate, and measured 1.47 to 6.81 (av. 4.29) µm long and 1.01 to 2.97 (av. 1.98) µm thick (n=100). The isolated strains were preliminarily identified as Boeremia sp. based on the morphological characteristics of colonies and conidia. (Aveskamp et al. 2010; Schaffrath et al. 2021). To confirm pathogen identity, the total genomic DNA of two isolates (LYB-2 and LYB-3) was extracted using the T5 Direct PCR kit. The internal transcribed spacer (ITS), 28S large subunit nrRNA gene (LSU), and ß-tubulin (TUB2) gene regions were PCR-amplified using primers ITS1/ITS4, LR0Rf/LR5r, and BT2F/BT4R (Chen et al. 2015), respectively. Sequences have been deposited in GenBank (ON908942-ON908943 for ITS, ON908944-ON908945 for LSU, ON929285-ON929286 for TUB2). BLASTn searches of generated DNA sequences from 2 purified isolates (LYB-2 and LYB-3) against GenBank showed high similarity (>99%) with the sequences of Boeremia linicola. Moreover, a phylogenetic tree was constructed based on the neighbor-joining method in MEGA-X (Kumar et al. 2018) and revealed that the 2 isolates were closest to B. linicola (CBS 116.76). Pathogenicity tests were conducted with the 2 isolates (LYB-2 and LYB-3) as described by Cai et al. (2009) with slight modifications. Each isolate was inoculated with three healthy annual P. notoginseng plants, and each leaf was inoculated with three drops of conidia suspension (106 spores/mL). Three P. notoginseng plants inoculated with sterile water were used as controls. All plants were covered with plastic bags incubated in a greenhouse (20℃, 90%RH, 12 h light/dark photoperiod). Fifteen days post-inoculation, all inoculated leaves showed similar lesions, and the symptoms were identical to those in the field. The pathogen was reisolated from symptomatic leaf spots, and the colony characteristics were identical to the original isolates. Control plants remained healthy, and no fungus was re-isolated. Morphological characteristics, sequence alignment and pathogenicity tests confirmed that B. linicola was the cause of P. notoginseng leaf spot disease. This is the first report of B. linicola causing leaf spot on P. notoginseng in Yunnan, China. The identification of B. linicola as the causal agent of the observed leaf spot on P. notoginseng is critical to the prevention and control of this disease in the future.

Comparative Transcriptome Analysis Reveals the Molecular Mechanism of Bacillus velezensis GJ-7 Assisting Panax notoginseng against Meloidogyne hapla.

The rhizosphere bacteria Bacillus velezensis GJ-7, as a biological control agent (BCA), has significant biological control effects on Meloidogyne hapla, and has strong colonization ability in the root of Panax notoginseng. In this study, we conducted a comparative transcriptome analysis using P. notoginseng plant roots treated with B. velezensis GJ-7 or sterile water alone and in combination with M. hapla inoculation to explore the interactions involving the P. notoginseng plant, B. velezensis GJ-7, and M. hapla. Four treatments from P. notoginseng roots were sequenced, and twelve high-quality total clean bases were obtained, ranging from 3.57 to 4.74 Gb. The Gene Ontology (GO) classification and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment showed that numerous DEGs are involved in the phenylpropane biosynthesis pathway and the MAPK signaling pathway in the roots of P. notoginseng with B. velezensis GJ-7 treatments. The analysis results of the two signaling pathways indicated that B. velezensis GJ-7 could enhance the expression of lignin- and camalexin-synthesis-related genes in plant roots to resist M. hapla. In addition, B. velezensis GJ-7 could enhance plant resistance to M. hapla by regulating the expression of resistance-related genes and transcription factors (TFs), including ETR, ERF, ChiB, WRKY22, and PR1. The expression of plant disease resistance genes in the roots of P. notoginseng with different treatments was validated by using real-time quantitative PCR (qRT-PCR), and the results were consistent with transcriptome sequencing. Taken together, this study indicated that B. velezensis GJ-7 can trigger a stronger defense response of P. notoginseng against M. hapla.

Effects of different soil moisture on the growth, quality, and root rot disease of organic Panax notoginseng cultivated under pine forests.

The under-forest economy in the agroforestry system can improve land use efficiency, protect ecological environment, and promote arable land sustainable development. However, the effects of soil moisture in the forest and irrigation strategies on the healthy growth of intercropping crops are still incomplete. Here, considering the organic Panax notoginseng cultivated under pine forests (PPF) as the research object, we explored the effects of different soil moisture on the physiological state, yield, quality and disease occurrence of PPF. Our results suggested that 80-85% and 95-100% field capacity (FC) treatments were more conducive to increased photosynthetic rate and biomass accumulation of PPF, but 50-55% and 65-70% FC treatments were more conducive to the accumulation of saponins in PPF leaves. Notably, the root rot index of PPF was highest under 95-100% FC (19.51) treatment, significantly higher than that under 65-70% FC (8.44) and 80-85% FC (10.21) treatments. Further, the rhizosphere microorganisms of PPF under different soil moisture treatments were sequenced, and the sequencing data analysis revealed that high soil moisture (95-100% FC) could destroy the microbial diversity balance and cause the accumulation of pathogens (Fusarium oxysporum and Ilyonectria radicicola), leading to a high incidence of root rot. The incidence of PPF root rot was negatively correlated with rhizosphere microbial diversity. Overall, our results highlight that the quantitative irrigation (80-85% FC) is conducive to maintaining the balance between yield, saponin content and disease occurrence of PPF, providing a practical basis for PPF irrigation strategy and promoting the sustainable development of PPF agroforestry system.

Volatile Organic Compounds of Bacillus velezensis GJ-7 against Meloidogyne hapla through Multiple Prevention and Control Modes.

The Bacillus velezensis GJ-7 strain isolated from the rhizosphere soil of Panax notoginseng showed high nematicidal activity and therefore has been considered a biological control agent that could act against the root-knot nematode Meloidogyne hapla. However, little was known about whether the GJ-7 strain could produce volatile organic compounds (VOCs) that were effective in biocontrol against M. hapla. In this study, we evaluated the nematicidal activity of VOCs produced by the fermentation of GJ-7 in three-compartment Petri dishes. The results revealed that the mortality rates of M. hapla J2s were 85% at 24 h and 97.1% at 48 h after treatment with the VOCs produced during GJ-7 fermentation. Subsequently, the VOCs produced by the GJ-7 strain were identified through solid-phase micro-extraction gas chromatography mass spectrometry (SPME-GC/MS). Six characteristic VOCs from the GJ-7 strain fermentation broth were identified, including 3-methyl-1-butanol, 3-methyl-2-pentanone, 5-methyl-2-hexanone, 2-heptanone, 2,5-dimethylpyrazine, and 6-methyl-2-heptanone. The in vitro experimental results from 24-well culture plates showed that the six volatiles had direct-contact nematicidal activity against M. hapla J2s and inhibition activity against egg hatching. In addition, 3-methyl-1-butanol and 2-heptanone showed significant fumigation effects on M. hapla J2s and eggs. Furthermore, all six of the VOCs repelled M. hapla J2 juveniles in 2% water agar Petri plates. The above data suggested that the VOCs of B. velezensis GJ-7 acted against M. hapla through multiple prevention and control modes (including direct-contact nematicidal activity, fumigant activity, and repellent activity), and therefore could be considered as potential biocontrol agents against root-knot nematodes.

Preparation of Biomass Biochar with Components of Similar Proportions and Its Methylene Blue Adsorption.

Rapeseed straw, bagasse, and walnut peel have a large amount of resource reserves, but there are few technologies for high value-added utilization. In the research of biochar, walnut green husk is rarely used as raw material. In addition, the three main components of biomass (lignin, cellulose, and hemicellulose) are present in similar proportions, and the differences between the physical and chemical properties of biochar prepared with similar amounts of biomass raw materials are not clear. Using three kinds of biomass of the same quality as raw materials, biochar was prepared via pyrolysis at 400 °C, and activated carbon was prepared via CO2 activation at 800 °C. The results showed that the pore numbers of the three kinds of biochar increased after activation, resulting in the increase of the specific surface area. The resulting numbers were 352.99 m2/g for sugarcane bagasse biochar (SBB)-CO2, 215.04 m2/g for rapeseed straw biochar (RSB)-CO2, and 15.53 m2/g for walnut green husk biochar (WGB)-CO2. Ash increased the amount of carbon formation, but a large amount of ash caused biochar to form a perforated structure and decreased the specific surface area (e.g., WGB), which affected adsorption ability. When the three main components were present in similar proportions, a high content of cellulose and lignin was beneficial to the preparation of biochar. The adsorption value of MB by biochar decreased with the increase of biomass ash content. After activation, the maximum adsorption value of MB for bagasse biochar was 178.17 mg/g, rapeseed straw biochar was 119.25 mg/g, and walnut peel biochar was 85.92 mg/g when the concentration of methene blue solution was 300 mg/L and the biochar input was 0.1 g/100 mL at room temperature. The adsorption of MB by biochar in solution occurs simultaneously with physical adsorption and chemical adsorption, with chemical adsorption being dominant. The optimal MB adsorption by SBB-CO2 was dominated by multimolecular-layer adsorption. This experiment provides a theoretical basis for the preparation of biochar and research on its applications in the future.

Comprehensive assessment of river ecological environment in nature reserve based on TOPSIS combined with grey correlation method.

The main driving factors of river ecological environment were analyzed to reveal the response mechanism of river ecosystem to ecological environmental factors. The results showed that the driving factors of river water quality were resistivity, COD and reoxidation potential, the driving factors of soil environment along river banks were total phosphorus, total nitrogen and pH, and the driving factors of plant nutrition along river banks were total potassium and total nitrogen. The contribution rates of water quality, soil and plant to river ecological environment health were 43, 51 and 70%, respectively. The comprehensive ecological environment of Menghuo River, Gongyihai, Arulendi River, Yiniu River, Dahonggou River and Nanya River is superior to each other, with the comprehensive proximity index of 0.6258, 0.5908, 0.5524, 0.5265, 0.5195 and 0.3889, respectively. Each detection index can accurately and truly invert the ecological environment health status of rivers in the protected areas.

Rapid screening and quantification of heavy metals in traditional Chinese herbal medicines using monochromatic excitation energy dispersive X-ray fluorescence spectrometry.

Traditional Chinese herbal medicines are subject to heavy metal contamination. Standard detection methods are too complicated, time-consuming, and expensive for routine analysis, so low-cost methods are in high demand for rapid on-site screening. This study reports a high-sensitivity X-ray fluorescence (HS-XRF) method to determine As, Pb, and Cd residues simultaneously in herbal medicines. It couples monochromatic excitation energy dispersive X-ray fluorescence spectrometry and the fast fundamental parameters method. Each test takes only 10-30 min and costs 1/10th to 1/5th of the standard method. The detection limits, precision and accuracy were evaluated using different approaches, and application notes in practice are also proposed. This study is the first attempt to establish and evaluate HS-XRF in analyzing multiple heavy metals in herbal medicines. This rapid screening method would promote the testing efficiency and thus improve the monitoring of heavy metal contamination in herbal medicines.

First Report of Leaf Spot on Panax notoginseng Caused by Caryophylloseptoria pseudolychnidis in Yunnan, China.

Panax notoginseng is a unique traditional medicinal plant in China, which has the effects of improving myocardial ischemia, protecting liver and preventing cardiovascular diseases (Jiang, 2020). In July 2021, gray-brown round spots were found on the leaves of P. notoginseng in the plantations of Lincang City (23º43´10˝N, 100º7´32˝E). By September, the symptoms were observed on more P. notoginseng plants, with incidence reaching 31%. Initial symptoms on leaves were small, brown spots that expanded, with black granular bulges on the lesions, often surrounded with yellow halo. As the disease progressed, multiple lesions merged, leaves became yellow, and abscission occurred. To isolate the causal pathogen, twelve symptomatic leaves were randomly obtained from twelve P. notoginseng plants. Small pieces of infected leaf tissues (about 5 mm2) were disinfected with 75% ethanol for 30 s, soaked in 2% sodium hypochlorite for 3 min, and then rinsed 3 times with sterile water and blotted dry. Sample tissues were plated on potato dextrose agar (PDA) plates incubated at 25℃ for 5 days with 12 h light/dark photoperiod. Hyphal-tips from the growing edge of colonies were transferred to fresh PDA to obtain pure cultures. Eight isolates were obtained with similar colony morphology, gray (top view) or black (back view) coloration, with a villous surface, and slow-growing on PDA. Conidia were hyaline, slender and obtuse to subobtuse at both ends, 10.3 to 52.62 (av. 25.2) µm × 1.4 to 4.0 (av. 2.4) µm (n=200) in size. Characteristics of the colonies and conidia were consistent with Caryophylloseptoria pseudolychnidis as described by Quaedvlieg et al. (2013) and Verkley et al. (2013). Genomic DNA of three representative isolates (LINC-4 to LINC-6) was extracted, and the rDNA-ITS region, ACT, and LSU gene regions were amplified and sequenced using the primer pairs ITS4/ITS5, 512F/783R, and LSU1Fd/LR5, respectively. Sequences have been deposited in GenBank (OK614104-OK614106 for ITS, OK614109-OK614111 for LSU, OK628350-OK628352 for ACT). BLAST search showed that all sequences were 98% to 100% homology with the corresponding sequences of C. pseudolychnidis. ITS sequences of the three isolates (LINC-4 to LINC-6) showed 99.21% identity (500/504 bp) to C. pseudolychnidis strain CBS 128630 (GenBank accession no. NR156266). LSU sequences of the three isolates showed 99.76% identity (823/825 bp) to C. pseudolychnidis strain CBS 128630 (MH876481). For ACT sequences, LINC-4 and LINC-5 showed 98.53% identity (201/204 bp) to C. pseudolychnidis strain 128614 (KF253599); LINC-6 showed 99.02% identity (202/204 bp) to C. pseudolychnidis strain 128614 (KF253599). Further, the neighbor-joining and maximum-likelihood method were used for multilocus phylogenetic analysis of the obtained sequences using MEGA-X (Kumar et al. 2018). The three isolates were clustered in the same clade with two C. pesudolychidis from database. Three isolates (LINC-4 to LINC-6) were tested for pathogenicity to confirm Koch's postulates. Annual potted P. notoginseng was inoculated with spore suspension (105 spores.mL-1). Each isolate was inoculated onto two leaves each of five P. notoginseng plants. The controls were similarly mock-inoculated with sterile water. To maintain high humidity (>90% RH), all plants were placed in transparent plastic boxes in a greenhouse at 25℃ with a 12 h light/dark photoperiod. Fifteen days post-inoculation, inoculated leaves showed similar symptoms to those observed in the field, and control plants remained healthy. The pathogen were reisolated from symptomatic leaf spots, and the colony characteristics were the same as those of the original isolates. Morphological characteristics, molecular data, and Koch's postulates tests confirmed C. pseudolychnidis as the cause of P. notoginseng leaf spot disease. To our knowledge, this is the first report of C. pseudolychnidis causing leaf spot on P. notoginseng in Yunnan, China. The spread of this disease might pose a serious threat to the production of P. notoginseng. The occurrence and spread of this pathogen should be further studied in order to formulate reasonable control measures.

One-Step Pyrolysis of Nitrogen-Containing Chemicals and Biochar Derived from Walnut Shells to Absorb Polycyclic Aromatic Hydrocarbons (PAHs).

The pyrolysis of biomass is an efficient means of utilizing biomass resources. Biomass can be converted into various high-performance chemicals and functional materials through pyrolysis. However, current pyrolysis technologies suffer from low conversion rates and single products, so the preparation of nitrogen compounds with high economic value remains a challenge. The walnut shell was soaked in three nitrogen-containing compound solutions before carbonization to produce high-value-added nitrogen-containing chemicals (with a nitrogen content of 59.09%) and biochar for the adsorption of polycyclic aromatic hydrocarbons (PAHs). According to biochar analysis, biochar has a porous structure with a specific surface area of 1161.30 m2/g and a high level of rocky desertification. The surface forms a dense pyrrole structure, and the structure produces π-π interactions with naphthalene molecules, exhibiting excellent naphthalene adsorption with a maximum capacity of 214.98 mg/g. This study provides an efficient, rapid, and environmentally friendly method for producing nitrogen-containing chemicals with high-added value and biochar.

Preparation of Multicolour Solid Fluorescent Carbon Dots for Light-Emitting Diodes Using Phenylethylamine as a Co-Carbonization Agent.

Carbon dots (CDs), as a new type of photoluminescent nanomaterial, have attracted extensive attention in various fields because of their unique luminescence properties. However, CDs will exhibit fluorescence quenching in the solid state or aggregate state, which limits their application. In this paper, a unique strategy is proposed to regulate solutions to achieve multicolour fluorescence of CDs in the solid state. We report the successful preparation of orange, green and blue solid fluorescent CDs using citric acid, urea and phenylethylamine as precursors and methanol, ethanol and water as solvents, respectively. The solid-state fluorescence of CDs may be caused by the linkage of the phenylethyl structure to the surface of CDs during formation, which effectively disperses the CDs and prevents π-π interactions between graphitized nuclei. Meanwhile, multicolour solid fluorescent CDs are realized by adjusting the solvent in the preparation process. Based on the excellent fluorescence properties of CDs, orange, green and blue light-emitting diodes (LEDs) are prepared. A white LED (WLED) can be obtained by mixing the three colours of solid fluorescent CDs, which shows the application potential of CDs in display lighting equipment.

Solvent-Free Preparation of Tannic Acid Carbon Dots for Selective Detection of Ni2+ in the Environment.

Carbon dots (CDs) are widely used nanomaterials that not only exhibit good biocompatibility and photostability, but also benefit from a simple preparation process and easy functionalization, making them promising for broad applications in the fields of heavy metal ion detection and optoelectronic devices. Based on the excellent optical properties of CDs and the current situation of increasing energy shortages, this paper selects the natural polyphenolic compound tannic acid (TA) found in biomass materials as the carbon source and innovatively adopts a simple and convenient solvent-free pyrolysis method without auxiliary reagents or solvents. The CDs with good water solubility and certain fluorescence properties were directly prepared under the condition of high temperature, and the obtained CDs exhibited blue fluorescence, and a high QY of 35.4% was obtained at 300 °C. The analysis and results demonstrate the selectivity of these CDs for the detection of various metal ion solutions. In particular, these CDs are sensitive to Ni2+ and can be used as fluorescent sensors for the efficient and sustainable detection of Ni2+, whereas previous sensors were often specific to Fe3+ and Hg2+. Thus, a new sensing technique has been developed for the detection of Ni2+ to achieve more sensitive and rapid detection.