Pseudostellaria Heterophylla Research Articles

First Report of Epicoccum sorghinum Causing Leaf Blight on Pseudostellaria heterophylla in China.

Pseudostellaria heterophylla (Caryophyllaceae) is a perennial herb with tuberous roots. It is commonly cultivated as a medical plant for the pharmaceutical industry (Qin et al., 2025). In June 2024, serious leaf blight was observed on P. heterophylla in Tongren, Guizhou Province, China (28°10'40″N, 108°2'38″E). In a 0.33 ha field, the disease incidence was more than 70%. The lesions initially appeared as spots that later enlarged and coalesced into larger necrotic patches of blight. To identify the pathogen, 12 typical symptomatic P. heterophylla leaves were collected. Symptomatic leaf tissues (5 × 5 mm) were excised from infected margins, surface-sterilized sequentially with 75% ethanol (1 min) and 2% sodium hypochlorite (1 min), rinsed three times in sterile water, air-dried, and plated on potato dextrose agar (PDA; pH 7.0). Cultures were incubated at 25°C under dark conditions for 3 days. Nine isolates showed similar morphology on PDA with cottony aerial mycelia and pink concentric rings observed on the upper surface of the culture. Chlamydospores were identified, measuring 4.5 to 27.4 × 5.7 to 36.2 μm (n = 50). Conidia were unicellular, hyaline, oval, and measured 2.4 to 6.3 × 1.1 to 3.4 μm (n = 50). Morphological characteristics matched the description of Epicoccum sorghinum (Chen et al., 2017). DNA fragments were amplified using primers ITS1/ITS4 (White et al., 1990), TUB2Fd/TUB4Rd (Woudenberg et al., 2009), and LROR/LR5 (Vilgalys and Hester, 1990). Sanger sequencing was performed by Sangon Biotech (Shanghai, China), with sequences from strains SYDJ15, SYDJ16, and SYDJ19 deposited in GenBank (SYDJ15: PV133704, PV178136, and PV133774; SYDJ16: PV133736, PV178135, and PV133779; and SYDJ19: PV133741, PV178134, and PV133788). BLASTn analysis revealed >99% nucleotide identity between the ITS, TUB2, and LSU sequences of SYDJ15/16/19 and E. sorghinum (ITS (OR917791): 100%, 509/509 bp; 99.80%, 506/507 bp; 100%, 504/504 bp; TUB2: 99.72%, 362/363 bp, MN603100; 100%, 354/354 bp, KT783666; 99.12%, 450/454 bp, KT783666, and LSU (MK516207): 99.78%, 906/908 bp; 99.78%, 910/912 bp; 99.89%, 908/909 bp). Based on concatenated ITS, TUB2, and LSU sequences, the constructed phylogenetic tree confirmed that these isolates were E. sorghinum. To confirm pathogenicity, 1 mL of isolate SYDJ15 (10⁶ conidia/mL) was sprayed onto the leaves of three healthy 1-month-old P. heterophylla plants, and three control plants were sprayed with sterilized distilled water. The experiment was carried out in a greenhouse at 23±2℃ and 85% humidity. By 10 days post-inoculation, all inoculated leaves exhibited symptoms consistent with those observed in the field, whereas the controls were asymptomatic. The experiment was repeated three times with similar results. Based on morphological and molecular identifications, the fungus re-isolated from lesions was identified as E. sorghinum, thus completing Koch's postulates. The host range of E. sorghinum is broad and includes cereal crops, ornamental plants, and medicinal plants (Du et al., 2020; Zou et al., 2024), and it causes leaf blight disease that leads to considerable losses in agricultural production. To the best of our knowledge, our study represents the first report of E. sorghinum causing leaf blight on P. heterophylla in China. Further studies are warranted to prioritize the development of optimized control strategies for its sustainable management.

Detection of TuMV by a toehold switch sensor coupled with NASBA amplification in Pseudostellaria heterophylla

Pseudostellaria heterophylla (P. heterophylla) is a perennial herb that has been used as a medicinal food for hundreds of years in China. Viral infections during the production of P. heterophylla severely reduce the yield and quality. Turnip mosaic virus (TuMV) is a common and highly variable viral pathogen in P. heterophylla plants. A high-efficiency diagnostic system is urgently needed to control and alleviate TuMV infection. However, the current detection methods still have various deficiencies that limit their field application. Here, a cell-free expression system relying on nucleic acid sequence-based amplification (NASBA) with toehold switch sensors and a visual reporter for color change was developed and introduced for TuMV detection in P. heterophylla. After designing and screening the approach, the selected sensitive sensor was able to detect 1 pM TuMV RNA fragments within 40 min, and the detection limit was less than 10 fM if the time was extended to 90 min. The sensor exhibited high specificity, with no cross-reactivity detected when tested against cucumber mosaic virus, another prevalent viral pathogen in P. heterophylla. In addition, in in-field samples, TuMV was successfully detected directly from both purified and crude RNA extracts in approximately 3 h. This cell-free synthetic biology tool is rapid, sensitive, specific and field-applicable and provides high-capacity and low-cost diagnostics for TuMV in P. heterophylla, as well as various viruses in herbs and other host plants.

Identification of a key peptide cyclase for novel cyclic peptide discovery in Pseudostellaria heterophylla.

Identification of a key peptide cyclase for novel cyclic peptide discovery in Pseudostellaria heterophylla.

First Report of Leaf Spot on Pseudostellaria heterophylla Caused by Pestalotiopsis kenyama in Guizhou, China.

Pseudostellaria heterophylla is a perennial herb of Caryophylaceae family, cultivated in Guizhou and Jiangsu province of China. This herb is particularly important in Chinese herbal medicine, especially valued for its reputed benefits to the immune system (Choi et al. 2016). In May 2023, the incidence of P. heterophylla leaf spot was approximately 50% in Cengong County (108° 37' E, 27° 36' N), Guizhou Province, southwestern region of China. The symptoms gradually developed from small white lesions to larger lesions. Fifteen symptomatic leaves from different plants were collected and fungal isolates were obtained by a single spore method (Liu 2010). Briefly, the conidia on the leaves were collected in a sterile tube to prepare a conidial suspension, which was gradually diluted to a single spore under a microscope and then transferred to PDA at 28°C. Finally, a total of 18 isolates were obtained. Colonies reached 89 mm in diameter after 7 days of incubation at 28°C on PDA. It was white, irregular and had gregarious conidiomata measuring 100 - 400 µm. These conidia were fusiform, slightly curved, measuring 24.5 - 35.5 × 4.0 - 5.5 µm (n=50). The basal and apical cells are hyaline, with 1, 1-3 accessory filaments, respectively, and the middle three cells are light brown. The conidiogenous cell was discrete and nearly cylindrical. Based on the morphological characteristics, the isolates were initially identified as Pestalotiopsis (Liu et al. 2017). To confirm the identification, the internal transcribed spacer region (ITS) gene, large subunit (LSU), the translation elongation factor-1 (TEF1) gene, and the β-tubulin (TUB2) gene were amplified using ITS4/ITS5, LR5/LROR, EF1-728F/EF2, and Bt2a/T1 primers, respectively (Liu et al. 2017; Carbone et al. 1999; O' Donnell et al. 1998; Santos et al. 2010). The ITS, LSU, TEF1 and TUB2 sequences of three randomly selected isolates, GUCC0218 (OR782588, OR782589, OR791708 and OR791719), GUCC0220 (PP837725, PP837723, PP855992 and PP855993) and GUCC0221 (OR782591, OR791002, OR791709 and OR791720), showed 100% nucleotide identities with the sequences of P. kenyama (CBS 442.67) in GenBank (KM199302, KM116234, KM199502 and KM199395, respectively). The phylogenetic tree based on ITS, LSU, TEF1 and TUB2 sequences, using maximum likelihood (ML), maximum parsimony (MP) and Bayesian inference (Bl) methods, indicated that three isolates were most closely related to P. kenyama (CBS 442.67), supported by 100%/1/99% bootstrap values. Nine 4-month-old healthy P. heterophylla plants were sprayed with a conidial suspension (1 × 106 conidia/mL) the three isolates and three other plants were sprayed with sterile water as a control, and all treated plants were incubated in a greenhouse at 28°C (85% humidity). After 7 days, typical symptoms similar to those observed in the field appeared on the leaves of inoculated plants, while the control plants remained asymptomatic. Pestalotiopsis kenyama was re-isolated from infected leaves but not from controls. Pestalotiopsis kenyama is accountable for Camellia sinensis gray blight (Liu et al. 2017), Castanea mollissima leaf spot (Jiang 2021). Our findings will provide a basis for the correct diagnosis and management of leaf spot on P. heterophylla. To our knowledge, this is the first report of leaf spot disease caused by P. kenyama on P. heterophylla in China.

Long-Term Effects of Vegetative-Propagation-Mediated TuMV-ZR Transmission on Yield, Quality, and Stress Resistance in Pseudostellaria heterophylla.

Pseudostellaria heterophylla (Miq.) Pax (P. heterophylla) was a valued traditional Chinese herbal medicine. Previous studies have shown that P. heterophylla TuMV spreads during the vegetative propagation cycle using tuberous roots as carriers. However, the transmission mechanism of TuMV in P. heterophylla and its effects on host growth remain to be elucidated. In this study, virus-free P. heterophylla culture seedlings were infected with control, TuMV-ZR, and TuMV-ZR-EGFP, thereby resulting in the initial infection cycle of IF1 (TIF1, TEIF1) and control NIF1, and used these roots to propagate the subsequent infection cycle IF2 (TIF2, TEIF2) and control NIF2. The transmission of TuMV-ZR seedlings was tracked by EGFP signal, and their yield, quality, and resistance were analyzed simultaneously in the critical growth period of the plants. The results indicated that TuMV-ZR accumulated in the tuberous roots of IF1 plants, subsequently migrated to IF2 during seedling growth, and was re-stored in IF2 tuberous roots, thereby forming a simple virus transmission cycle. Meanwhile, the tuberous roots of IF1 and IF2 P. heterophylla showed lower fresh weight, dry weight, soluble sugar, and saponin levels compared to NIF1 and NIF2, respectively. TuMV caused a significant reduction in chlorophyll synthesis in IF1 and IF2 P. heterophylla, resulting in impairment to their photosynthetic organs and efficiency. The measurement of stress resistance in IF1 and IF2 P. heterophylla revealed that continuous viral infection disrupted antioxidant enzyme activity, increased the content of MDA, enhanced the activity of PAL, and elevated the levels of intracellular osmotic substances in both propagation cycles. The findings indicated that the accumulation of the TuMV-ZR virus during two successive vegetative propagation cycles induced physiological stress, impaired photosynthesis, and caused progressive yield and quality decline with each cycle. This study systematically examined the impact of TuMV-ZR persistence during vegetative propagation on key physiological and biochemical indices in P. heterophylla, providing critical data to clarify vegetative-propagation-mediated germplasm degradation.

The comparative genomic analysis provides insight into the divergent inhibitory activity metabolites in pathogen-driven three Pseudomonas palleroniana strains against primary pathogens of Pseudostellaria heterophylla

Pseudostellaria heterophylla (Miq.) Pax ex Pax et Hoffm. is a member of the Caryophyllaceae family, in which dried tuberous root is the well-known traditional Chinese medicine (TCM) and a widespread food ingredient in Asia. In recent years, the large-scale cultivation of P. heterophylla has led to frequent infectious diseases caused by multiple pathogens. However, efficient and safe approaches for preventing and managing P. heterophylla diseases have become urgent for this high-quality industrial development. Herein, a culturable microbiome of diseased P. heterophylla rhizosphere soil was constructed, and the broad-spectrum antifungal activity of Pseudomonas was screened. Three P. palleroniana strains, B-BH16-1, B-JK4-1, and HP-YBB-1B, were isolated and identified with vigorous antifungal activity by confrontation method. We employed the PacBio RS II single-molecule real-time (SMRT) sequencing and Illumina sequencing methods to obtain the genome of these three isolates. Phylogenetic, synteny, and ANI analysis showed that the lineage between strain B-JK4-1 with B-BH16-1 or HY-YBB-1B was closer than that between strain B-BH16-1 with HP-YBB-1B. The comparative genome of strains B-BH16-1, B-JK4-1, and HP-YBB-1B showed marked differences in secondary metabolite biosynthesis genes among these three P. palleroniana strains. Strain B-BH16-1, B-JK4-1, and HP-YBB-1 produced tolaasin I/tolaasin F (23 genes), sessilin A (37 genes), and putisolvin (39 genes), respectively. CAZyme analysis showed that 126, 129, and 127 CAZymes were identified in strains B-BH16-1, B-JK4-1, and HP-YBB-1B genomes, which genes in auxiliary activities (AA), carbohydrate esterases (CE), and glycosyl transferases (GT) categories were different among these three strains. These results provide new insights into the divergent antifungal metabolites in pathogen-driven three P. palleroniana strains against primary pathogens of Pseudostellaria heterophylla.

Production and Active Ingredients of Pseudostellaria Heterophylla in Biochar Amended Soil Under Elevated CO2 and Temperature

Production and Active Ingredients of Pseudostellaria Heterophylla in Biochar Amended Soil Under Elevated CO2 and Temperature

Pseudostellaria heterophylla (Miq.) Pax, a traditional folk medicine, ameliorates colorectal cancer by remodeling the tumor immune microenvironment.

Pseudostellaria heterophylla (Miq.) Pax, a traditional folk medicine, ameliorates colorectal cancer by remodeling the tumor immune microenvironment.

Total saponin extracts of Pseudostellaria heterophylla ameliorates meibomian gland dysfunction through SCD1/SPT1/ceramide axis.

Total saponin extracts of Pseudostellaria heterophylla ameliorates meibomian gland dysfunction through SCD1/SPT1/ceramide axis.

Dual-virus co-infection reduces photosynthetic rate, yield, and sensitivity of photosynthetic rate to leaf-air VPD in <i>Pseudostellaria heterophylla</i>

Dual-virus co-infection reduces photosynthetic rate, yield, and sensitivity of photosynthetic rate to leaf-air VPD in <i>Pseudostellaria heterophylla</i>

Development of a TaqMan qPCR for the Simultaneous Detection of the TuMV and BBWV2 Viruses Responsible for the Viral Disease in Pseudostellaria heterophylla

Pseudostellaria heterophylla (Miq.) Pax, a highly valued Chinese medicinal plant, is experiencing a notable decline in yield and quality due to viral diseases, particularly caused those by TuMV and BBWV2. Currently, the absence of a quantitative detection method for these viruses in P. heterophylla impedes the accurate diagnosis. The development of an accurate quantitative detection method is thus essential for effectively managing viral diseases in this plant. In this study, singleplex and duplex TaqMan qPCR were developed for the detection of the two viruses, based on two viral cloning vectors. Concurrently, the levels of both viruses were examined in the main produced regions of P. heterophylla. Furthermore, the levels of BBWV2 were examined during its infection of P. heterophylla. The optimal singleplex qPCR employed 0.1 μM of hydrolysis probe and 0.1 μM of primer for TuMV, while 0.2 μM of hydrolysis probe and 0.1 μM of primer were utilised for BBWV2. In contrast, the duplex qPCR employed the use of 0.1 μM of the upstream/downstream primer from each primer pair, with 0.2 μM of the respective hydrolysis probes. The 95% limit of detection (LOD) for singleplex qPCR was 734 copies for TuMV and 20 copies for BBWV2, while the 95% LOD for duplex qPCR was 945 copies for TuMV and 47 copies for BBWV2. Furthermore, the intra- and inter-assay coefficients of variation were found to be less than 1.2% for both singleplex and duplex qPCR. Of the P. heterophylla sampled 60 sites, 96% were found to be infected by one of two viruses. The levels of BBWV2 in N. benthamiana and P. heterophylla demonstrated an initial increase, followed by a subsequent decrease. The TaqMan qPCR methods provide a technical foundation for the monitoring of virus infections in P. heterophylla.

Insights into the Genomic Background of Nine Common Chinese Medicinal Plants by Flow Cytometry and Genome Survey.

Medicinal plants have long played a crucial role in healthcare systems, but limited genomic information on these species has impeded the integration of modern biological technologies into medicinal plant research. In this study, we selected nine common medicinal plants, each belonging to a different plant family, including Sarcandra glabra (Chloranthaceae), Nekemias grossedentata (Vitaceae), Uraria crinita (Fabaceae), Gynostemma pentaphyllum (Cucurbitaceae), Reynoutria japonica (Polygonaceae), Pseudostellaria heterophylla (Caryophyllaceae), Morinda officinalis (Rubiaceae), Vitex rotundifolia (Lamiaceae), and Gynura formosana (Asteraceae), to estimate their genome sizes and conduct preliminary genomic surveys. The estimated genome sizes by flow cytometry were 3.66 Gb, 0.65 Gb, 0.58 Gb, 1.02 Gb, 3.96 Gb, 2.99 Gb, 0.43 Gb, 0.78 Gb, and 7.27 Gb, respectively. The genome sizes of M. officinalis, R. japonica, and G. pentaphyllum have been previously reported. Comparative analyses suggest that variations in genome size may arise due to differences in measurement methods and sample sources. Therefore, employing multiple approaches to assess genome size is necessary to provide more reliable information for further genomic research. Based on the genome survey, species with considerable genome size variation or polyploidy, such as G. pentaphyllum, should undergo a ploidy analysis in conjunction with population genomics studies to elucidate the development of the diversified genome size. Additionally, a genome survey of U. crinita, a medicinal plant with a relatively small genome size (509.08 Mb) and of considerable interest in southern China, revealed a low heterozygosity rate (0.382%) and moderate repeat content (51.24%). Given the limited research costs, this species represents a suitable candidate for further genomic studies on Leguminous medicinal plants characteristic of southern China. This foundational genomic information will serve as a critical reference for the sustainable development and utilization of these medicinal plants.

Simulation of Pseudostellaria heterophylla distribution in China: assessing habitat suitability and bioactive component abundance under future climate change scenariosplant components.

Pseudostellaria heterophylla is used in traditional Chinese medicine, so ensuring an adequate supply of plant material with high levels of bioactive components is important. Using an optimized maximum entropy niche model and assays of bioactive components from cultivation samples, this study started from the plant's natural distribution area and estimated correlations of ecological factors with not only abundance of the plant but also abundance of polysaccharides and heterophyllin B. These correlations were combined with the spatial analysis function in ArcGIS to generate maps of the suitability of different habitats in China for cultivating P. heterophylla under current climate conditions and different models of climate change. The following ecological factors emerged as particularly important for habitat suitability: precipitation of driest month and driest quarter, annual precipitation, annual mean temperature, temperature seasonality, and mean temperature of coldest quarter, contributing to a cumulative total of 87%. Under current climate conditions, optimum habitats of P. heterophylla were mainly distributed in the southwestern region (Guizhou) and eastern regions (Anhui, Zhejiang, Fujian, Jiangsu) of China, and only 0.197×106 km2 of these areas were optimum habitat. In future climate change scenarios, the optimal habitat area of P. heterophylla exhibited an increase across different time periods under the SSP5-8.5 climate scenario. By the 2090s, distribution area of high heterophyllin B content under SSP5-8.5 climate scenarios will increase significantly, distribution area of high polysaccharide content had little change under all three climate scenarios (SSP 1-2.6, 2-4.5, 5-8.5). The center of mass of suitable habitat migrates southwestward under scenario SSP 1-2.6 and SSP 2-4.5, while it migrates northward under scenario SSP 5-8.5. Under the three climate scenarios, the center of mass of suitable habitat migrated consistently with that of high polysaccharide content but differed from that of high heterophyllin B content. These findings provide a crucial foundation for cultivating P. heterophylla with superior medicinal properties, developing adaptive management strategies to enhance conservation efforts, and ensuring sustainable utilization in the face of global climate change.

Pseudostellaria heterophylla cultivar mixtures driven changes in rhizosphere metabolites to suppress soil-borne Fusarium disease

Pseudostellaria heterophylla cultivar mixtures driven changes in rhizosphere metabolites to suppress soil-borne Fusarium disease

Correlation analysis between Radix Pseudostelariae quality and rhizosphere soil factors of Pseudostellaria heterophylla in a cultivation region, China.

Pseudostellaria heterophylla, known for its significant bioactive ingredients, offers potential health benefits. Amounts of bioactive compounds of the tuberous root of cultivated Pseudostellaria heterophylla are sensitive to environmental conditions. We selected 22 sampling sites in Guizhou Province, China, a primary Pseudostellaria heterophylla planting area. We analyzed polysaccharides, water-soluble extractives, total ash and inorganic elements (Fe, Mn, Zn, Mg and Ca) in Radix Pseudostellariae, and pH, organic carbon (OC), available nitrogen (AN), available phosphorus (AP), available potassium (AK) and inorganic elements in the soil. Our study revealed a substantial presence of polysaccharides (85.00-181.00 mg g-1), water-soluble extractives (47.52-57.63%) and total ash (1.87-3.39%) in Radix Pseudostellariae. Polysaccharides and total ash showed no sensitivity to soil pH. Radix Pseudostellariae collected from soil with pH > 7 exhibited slightly higher levels of water-soluble extractives, Mg and Ca than that from soil with pH < 5. Conversely, soil with a pH less than 5 had higher OC, AN, AP and AK contents. Water-soluble extractives in Radix Pseudostellariae were negatively correlated with soil pH but positively correlated with OC and AN. The results imply that the sequestration of soil nutrients over long-term Pseudostellaria heterophylla cultivation could negatively impact the accumulation of some bioactive ingredients in Radix Pseudostellariae. This study has a profound implication for enhancing the quality of Radix Pseudostellariae of artificially cultivated Pseudostellaria heterophylla. © 2024 Society of Chemical Industry.

Structural characterisation of a novel polysaccharide from pseudostellaria heterophylla fibrous root and its anti-inflammatory and antioxidant activities in vitro

A novel water-soluble polysaccharide, named PF90-1, with a molecular weight of 1.8 kDa, was isolated and purified from the fibrous root of Pseudostellaria heterophylla. PF90-1 is composed of Gal, Glc and Man in a molar ratio of 73.61: 19.11: 7.28. Methylation analysis revealed that PF90-1 comprises of T-Galp, 1,4-Galp, 1,3,4-Galp, 1,2,3,4-Galp, T-Glcp and 1,3-Manp in a molar ratio of 37.89: 9.37: 17.01: 12.01: 15.88: 7.83. Bioactivity experiments showed that PF90-1 significantly improved lipopolysaccharide (LPS)-induced inflammatory damage in RAW264.7 cells by inhibiting nitric oxide (NO) production and reducing the levels of pro-inflammatory factors (IL-1β and TNF-α). In addition, PF90-1 exhibited strong antioxidant effects, protecting PC12 cells from H2O2-induced oxidative damage. This findings suggest that PF90-1 holds potential therapeutic value for the treatment of inflammatory and oxidative injuries.

Plant growth-promoting rhizobacteria enhance active ingredient accumulation in medicinal plants at elevated CO2 and are associated with indigenous microbiome.

Plant growth-promoting rhizobacteria (PGPR) and elevated CO2 (eCO2) have demonstrated their individual potential to enhance plant yield and quality through close interaction with rhizosphere microorganisms and plant growth. However, the efficacy of PGPR under eCO2 on rhizosphere microbiome and, ultimately, plant yield and active ingredient accumulation are not yet fully understood. This study investigated how the medicinal plant Pseudostellaria heterophylla (P. heterophylla) and its rhizosphere microbes respond to PGPR (Bacillus subtilis and Pseudomonas fluorescens) at eCO2 (1,000 ppm). It was found that the yield and active ingredient polysaccharides accumulation in the tuber of P. heterophylla were significantly increased by 38 and 253%, respectively. This promotion has been associated with increased root development and changes in the indigenous microbial community. Metagenomics analysis revealed a significant reduction in pathogenic Fusarium abundance in the rhizosphere. Potential biocontrol bacteria Actinobacteria and Proteobacteria were enriched, especially the genera Bradyrhizobium and Rhodanobacter. The reshaping of the rhizosphere microbiome was accompanied by the upregulation of biological pathways related to metabolite biosynthesis in the rhizosphere. These modifications were related to the promotion of the growth and productivity of P. heterophylla. Our findings highlighted the significant role played by PGPR in medicinal plant yield and active ingredient accumulation when exposed to eCO2.

Pathogen-driven Pseudomonas reshaped the phyllosphere microbiome in combination with Pseudostellaria heterophylla foliar disease resistance via the release of volatile organic compounds

BackgroundContinuous monocropping obstacles are common in plants, especially medicinal plants, resulting in disease outbreaks and productivity reductions. Foliar disease, mainly caused by Fusarium oxysporum, results in a severe decrease in the yield of Pseudostellaria heterophylla annually. Determining an effective biomethod to alleviate this disease is urgently needed to improve its productivity and quality.ResultsThis study screened thirty-two keystone bacterial genera induced by pathogens in P. heterophylla rhizosphere soil under continuous monocropping conditions. Pseudomonas, Chryseobacterium, and Flavobacterium, referred to as the beneficial microbiota, were significantly attracted by pathogen infection. The P. palleroniana strain B-BH16-1 can directly inhibit the growth and spore formation of seven primary pathogens of P. heterophylla foliar disease by disrupting fusaric acid production via the emission of volatile organic compounds (VOCs). In addition, strain B-BH16-1 enhances the disease resistance of P. heterophylla by obliterating the pathogen and assembling beneficial microbiota.ConclusionPathogen-induced Pseudomonas reshaped phyllosphere microbial communities via direct antagonism of pathogens and indirect disruption of the pathogen virulence factor biosynthesis to enhance disease suppression and improve yields. These results show that inhibiting pathogen virulence biosynthesis to reshape the plant microbial community using disease-induing probiotics will be an innovative strategy for managing plant disease, especially under continuous monoculture conditions.

Leaf grey spot caused by Arcopilus aureus on tobacco in China.

Tobacco (Nicotiana tabacum L.) is one of the most widely cultivated industrial crops worldwide. From April to July 2023, about 40% of tobacco seedlings in the greenhouse exhibited irregular taupe lesions in Zhengzhou, Henan Province, China. At an early stage of the lesion development, light grey spots with the diameter of 1-2 mm were observed, these spots gradually expanded and connected into large irregular lesions causing leaf wrinkling or withered. A total of 12 infected leaf tissues were sterilized with 75% ethanol for 45 s, rinsed three times in sterilized water and then plated on potato dextrose agar (PDA) medium for 10 days at 28°C in darkness. Seven fungal colonies that show the similar appearance were isolated and three of them (MB-1, MB-2 and MB-3) were used for subsequent identification. Colonies of these strains on PDA with loose mycelium and orange-red pigment on the underside, white aerial in the center and light yellow hyphae near the periphery, formed in the shape of a concentric ring pattern. Ascomata appeared from the 14th day, were black, spherical or ellipsoid with walls of textura angularis, and size was 53.8-101.1 μm × 50.3-104.3 μm (n=30). Terminal hairs were brown and straight, gradually tapering toward the tips. Asci clavate or fusiform, spore bearing part 16.2-29.2 × 7.3-11.4 μm (n=21), with 8 irregularly arranged ascospores, evanescent. Ascospores are brown at maturity, biapiculate, navicular or fusiform shapes with size of 8.7-12.8 μm × 4.8-6.9 μm (n=100), and more or less inaequilateral. Single spore strains derived from these strains exhibited the morphological features consistent with the original strains. The morphological characteristics of the fungus were consistent with the description of Arcopilus aureus (Chivers) X.W. Wang & Samson (= Chaetomium aureum Chivers) (Lee et al. 2019). Furthermore, the sequences of RPB2 region were amplified from these strains and the result sequences (GenBank accession no. OR513105-OR513108) all showed a 100.00% identity with A. aureus strain CBS 538.73 (GenBank accession no. KX976807.1). It was reported that the RPB2 gene was efficient in discriminating Arcopilus species (Tavares et al. 2022), thus a maximum likelihood (ML) phylogenetic tree based on the RPB2 gene sequences were constructed using MEGA 7.0 with 1000 replications of bootstrapping (Kumar et al. 2016), which revealed that these strains formed a well-supported clade with A. aureus strains of (CBS 153.52 and CBS538.73) (Wang et al. 2022). Pathogenicity analysis were performed on healthy flue-cured tobacco seedlings leaves (cv Y85) by using mycelial agar plugs (5 mm in diameter) and spore suspension (1×106 spores/mL), and the PDA plugs and sterile water were used for control group, respectively. Tobacco seedlings were incubated in a 25°C and 70% RH growth chamber. After seven days, the leaves showed obvious symptoms, with taupe lesions and yellow halos on the periphery, whereas no symptoms were found on the control leaves. The A. aureu was then reisolated from inoculated diseased leaves. Previously, A. aureus has been only reported to cause leaf black disease on Pseudostellaria heterophylla in China (Yuan et al. 2021). To our knowledge, this is the first reported of A. aureus causing tobacco leaf grey spot worldwide. Arcopilus aureus has been reported as a plant biocontrol fungus (Wang et al. 2013). However, due to the potential serious damage in tobacco seedlings caused by this fungus, the use of A. aureus as a plant biocontrol agent needs to be given more attention, and disease control measures of this pathogen should be developed.

Plant-soil hydraulic interaction and rhizosphere bacterial community under biochar and CO2 enrichment

Plant-soil hydraulic interaction and rhizosphere bacterial community under biochar and CO2 enrichment