The harpin protein Hpa1 has various beneficial effects in plants, such as promoting plant growth and inducing pathogen resistance. Our previous study found that Hpa1 could significantly alleviate the mosaic symptoms of tobacco mosaic virus (TMV) in Pinellia ternata, indicating that Hpa1 can effectively stimulate resistance. Here, the potential mechanism of disease resistance and field applicability of Hpa1 against TMV in P. ternata were further investigated. The results showed that 15 µg ml⁻¹Hpa1 had stronger antiviral activity than the control, and its protective effect was better than its curative effect. Furthermore, Hpa1 could significantly induce an increase in defense-related enzyme activity, including polyphenol oxidase, peroxidase, catalase, and superoxide dismutase, as well as increase the expression of disease resistance-related genes (PR1, PR3, PR5, and PDF1.2). Concurrently, Hpa1 significantly increased the content of some disease resistance-related substances, including hydrogen peroxide, phenolics, and callose, whereas the content of malondialdehyde was reduced. In addition, field application analysis demonstrated that Hpa1 could effectively elicit a defense response against TMV in P. ternata. Our findings propose a mechanism by which Hpa1 can prevent TMV infection in Pinellia by inducing systemic resistance, thereby providing an environmentally friendly approach for the use of Hpa1 in large-scale applications to improve TMV resistance in Pinellia.

Scutellaria baicalensis Georgi (SB), a plant of the Lamiaceae family, contains flavonoids with potent human health benefits. The full mechanistic details and regulatory networks related to the biosynthesis of these compounds in SB have been the focus of recent research but are still fragmented. Similarly, a complete account of the metabolites produced, specifically flavonoids, and their distribution in different parts of the plant is incomplete. To provide a more complete picture, herein we have explored the SB metabolites and differentially expressed genes in underground and aerial tissues. Of the 947 metabolites identified, 373 were differentially accumulated flavonoids (DAFs), and 147 of these were differentially accumulated in roots relative to other tissues. Interestingly, roots accumulated more baicalin and baicalein than aboveground tissues, but they were low in scutellarein and wogonoside, in contrast to previous reports. These differences may be attributed to either plant variety, age of the plants, or the extraction protocol. Transcriptomics analysis identified 56 key genes from the flavonoid synthesis pathway in all six SB plant tissues. A weighted gene correlation network analysis conducted using four DAFs (baicalin, baicalein, scutellarein and wogonoside) produced 13 modules. Baicalin and baicalein were positively correlated with one of these modules, whereas wogonoside and scutellarein were correlated with three other modules. Gene expression in these modules was consistent with the observed accumulation of these compounds in plant tissues. Fourteen structural genes were highly correlated with baicalin, baicalein and scutellarein, and 241 transcription factors (TFs) associated to these four compounds. The 13 highly correlated structural genes and 21 highly correlated TFs were used to construct correlation networks, where genes were identified to be highly correlated with flavonoid biosynthesis genes. Overexpression of some of these genes, namely, SbMYB8 (Sb02g25620), SbMYB14 (Sb09g00160) and SbbHLH94 (Sb07g11990), in SB callus increased flavonoid content and regulated the expression of genes involved in the flavonoid biosynthesis pathway, confirming their association to flavonoid production. Overall, the present work contributes to delineating the differences in flavonoid biosynthesis among different SB tissues.

Introduction:Astragalusmembranaceus Fisch. ex Bunge is a traditional botanical drug with antibacterial, antioxidant, antiviral, and other biological activities. In the process of industrialization of A. membranaceus, most of the aboveground stems and leaves are discarded without resource utilization except for a small amount of low-value applications such as composting. This study explored the antibacterial activity of A. membranaceus stem and leaf extracts to evaluate its potential as a feed antibiotic substitute.Materials and methods: The antibacterial activity of the flavonoid, saponin, and polysaccharide fractions in A. membranaceus stems and leaves was evaluated by the disk diffusion method. The inhibitory activity of the flavonoid fraction from A. membranaceus stems and leaves on B. cereus was explored from the aspects of the growth curve, cell wall, cell membrane, biofilm, bacterial protein, and virulence factors. On this basis, the flavonoid fraction in A. membranaceus stems and leaves were isolated and purified by column chromatography to determine the main antibacterial components.Results: The flavonoid fraction in A. membranaceus stems and leaves had significant inhibitory activity against B. cereus, and the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were 1.5625 and 6.25 mg/mL, respectively. A. membranaceus stem and leaf flavonoid fraction can induce death of B. cereus in many ways, such as inhibiting growth, destroying cell wall and cell membrane integrity, inhibiting biofilm formation, inhibiting bacterial protein synthesis, and downregulating virulence factor expression. In addition, it was clear that the main flavonoid with antibacterial activity in A. membranaceus stems and leaves was isoliquiritigenin. Molecular docking showed that isoliquiritigenin could form a hydrogen bonding force with FtsZ.Conclusion:A. membranaceus stem and leaf flavonoid fractions had significant inhibitory activity against B. cereus, and the main chemical composition was isoliquiritigenin.

The degradation of Pinus sylvestris var. mongholica plantations in Youyu County on the Loess Plateau has caused major ecological issues, though the mechanisms remain poorly understood. This study explores the effects of stand age and soil properties on the rhizosphere fungal community and their potential roles in plantation degradation. Soil samples were collected from plantations of different stand ages (13, 20, 25, and 35 years), and their fungal diversity and composition were analyzed using high-throughput sequencing. The results showed that soil organic carbon and total nitrogen declined with stand age due to high nutrient demand and limited litter input. The available phosphorus and available potassium (AK) contents were identified as key limiting factors, influencing ectomycorrhizal fungi abundance and the overall soil fungal diversity. With an increasing stand age, the fungal diversity decreased, the ectomycorrhizal fungi declined, and the pathogenic fungi increased, exacerbating plantation degradation. Regression analysis further indicated a significant negative correlation between AK content and stand age, suggesting potassium deficiency as a critical driver of tree health decline. This study highlights the pivotal role of soil nutrient availability in shaping rhizosphere fungal communities and sustaining P. sylvestris plantations, offering insights into degradation mechanisms and strategies to enhance forest resilience on the Loess Plateau.

Astragalus membranaceus is a model of traditional ‘homologous nature of medicine and food’. Its stems and leaves have been proven to have a variety of biological activities. In this study, high-throughput sequencing technology was used to sequence transcriptomics and metabolomics A. membranaceus stems and leaves at different growth stages (flowerless stage, flower bud stage, flowering stage, green fruit stage, mature fruit staged, and withering stage), and a regulation analysis was conducted on its differentially expressed genes and differentially accumulated metabolites. The results showed that five hub genes, PAL, CHI, AMIE, CAD, and PRX, were found to play a central regulatory role in flavonoid biosynthesis. The combined analysis of transcriptomics and metabolomics constructed a flavonoid metabolic regulatory network during the growth and development of A. membranaceus stems and leaves. At the same time, based on the significant antioxidant activity of isoquercitrin, three genes that may be related to isoquercitrin biosynthesis were screened, namely IF7MAT, FG3, and UGT78D2. The results of this study provide insights into the biosynthesis and comprehensive development and utilization of flavonoids in A. membranaceus.