Search Results (53)

The cultivation of asparagus (Asparagus officinalis L.) is plagued by two serious issues: “asparagus decline” and “asparagus replant problem”. The average lifespan of an asparagus plant is 15 to 20 years. However, its productivity decreases after a few years (asparagus decline). Even when these asparagus plants are replaced with new ones, the new plants remain unproductive (asparagus replant problem). The main causes of these problems are a Fusarium infection and asparagus autotoxicity. Several reviews have been conducted on Fusarium. Despite the accumulation of evidence on asparagus autotoxicity in the literature over the past four decades, no review has focused specifically on asparagus autotoxicity. It has been reported that asparagus growth is inhibited by asparagus root residues, leachates, root exudates, and rhizosphere soils. Several phenylpropanoids, including trans-cinnamic acid, p-coumaric acid, caffeic acid, and ferulic acid, have been identified as asparagus autotoxic substances in these root residues, root exudates, rhizosphere soils, growth media, and/or plant tissues. Tryptophan, 3,4-methylenedioxycinnamic acid, and iso-agatharesinol were also identified as asparagus autotoxic substances. These substances may cause autotoxicity by disrupting phytohormone levels, cellular metabolism, impairing membrane function, and by inducing oxidative stress. Although cinnamic, p-coumaric, caffeic, and ferulic acids have been reported to act as antibiotics, these compounds have also been shown to weaken the defense mechanisms of asparagus against pathogen infection, and enhance the Fusarium pathogenicity. The presence of these autotoxic substances, coupled with a Fusarium infection, may create a vicious cycle that worsens “asparagus decline” and “asparagus replant problem”. This is the first review to focus on the asparagus autotoxicity. Full article

Cashew (Anacardium occidentale L.), a vital tropical cash crop, may face yield declines in old plantations due to unexplored risks of autotoxicity. This study investigated the allelopathic and autotoxic potential of cashew plant under laboratory and greenhouse conditions. The laboratory bioassays with leaf and stem bark (10–200 mg) demonstrated a strong allelopathic effect, reducing lettuce radicle elongation to 7–46.0% and 9–79% of the control, respectively. Aqueous leaf extract (50 mg/mL) completely inhibited (0%) lettuce seed germination and reduced pepper germination to 42%. However, the root exudate of cashew seedlings did not have any inhibitory effect on the test plants. Greenhouse experiments simulating field litter fall revealed significant autotoxicity in cashew. Cashew seedlings grown in growth media amended with 10% cashew leaf powder exhibited severe growth suppression after 13 weeks, including a reduction in plant height by 58.2% compared to controls. Chlorophyll content, stem girth, and leaf number were also significantly reduced. This study concludes that cashew possesses significant allelopathic properties and a clear potential for autotoxicity, as directly evidenced by the suppressed growth of its own seedlings following the incorporation of leaf powder. These findings identify autotoxicity, mediated through leaf litter decomposition, as a critical risk factor for the replanting success and long-term sustainability of cashew orchards, necessitating further investigation into management strategies. Full article

Continuous cropping obstacle (CCO) is becoming a major restrictive factor limiting the sustainable development of morel industry. The species-specific autotoxicity of extracellular self-DNA (esDNA) may be one of the primary drivers underlying the occurrence of CCO. In this study, the effects of short fragments (≤250 bp) of esDNA or extracellular DNA (exDNA) on mycelial growth of cultivable Morchella eximia and M. sextelata were assayed. These effects were quantified using a response index (RI). The results indicated the dose-dependent, strain-specific, and conspecific autotoxicity of esDNA in cultivable morels. At ecologically relevant DNA concentrations, the strain-specific and conspecific growth inhibitory effects of esDNA in tested Morchella strains were consistently negative (RI < 0). Additionally, our study found that the growth-inhibitory effects of exDNA from M. sextelata on M. eximia strains were weaker than those observed in the reverse scenario. Taken together, our study suggests, for the first time, the conspecific autotoxicity of esDNA in cultivable Morchella under laboratory conditions, providing novel insights into the potential mechanisms of CCO and highlighting its prospective applications in morel production. Full article

To address the soil degradation and growth inhibition caused by long-term monoculture of the medicinal plant Chrysanthemum morifolium Ramat. (Hangju), we conducted a controlled experiment comparing a monoculture (control) with seven different intercropping combinations. The intercropping treatments consisted of the main crop paired with pepper, schizonepeta, edible amaranth, dandelion, maize, soya, and purple perilla. Comprehensive assessments were conducted, encompassing plant growth parameters and rhizospheric soil properties. The soil properties included physicochemical characteristics, enzyme activities, and phenolic acid content (4-hydroxybenzoic acid, vanillic acid, and ferulic acid). The results indicated that intercropping significantly altered the rhizosphere environment of Hangju (p < 0.05). Purple perilla and maize emerged as particularly effective companion plants. Intercropping with purple perilla enhanced the aboveground biomass accumulation of Hangju and increased the activities of rhizosphere catalase, sucrase, β-glucosidase, and neutral phosphatase, although it also elevated the contents of three autotoxic phenolic acids. In contrast, intercropping with maize improved Hangju biomass and enhanced the activities of sucrase, urease, neutral phosphatase, and protease, while concurrently reducing the concentrations of all three phenolic acids. Overall, maize demonstrated optimal performance in comprehensively improving soil health by modulating enzyme activities, whereas purple perilla showed a distinct advantage in directly promoting plant growth. Full article

Hydroponic systems enable constant and high-quality crop yields while avoiding soil-borne diseases and significant pedoclimatic limitations. Recycling nutrient solutions (NSs) makes these systems more environmentally friendly, but long-term cultivation often leads to a decline in the quality and quantity of final products. Biochar and compost tea (CT) are an emerging nature-based solution known to improve both soil and plant health. This study investigates whether biochar or CT treatments can counteract the physiological and productive decline observed in recycled hydroponic systems. We established a closed floating raft system in a controlled-environment greenhouse, cultivated basil (Ocimum basilicum L. cv. Eleonora) over five cycles (conditioning phase), and then performed a last cycle (recovery phase) with the application of either compost tea or biochar filtration. Plant physiology and growth parameters were monitored. As expected, basil plants grown in untreated recycled NS showed significantly lower yields and dry matter content and reduced physiological values compared to controls (fresh NS). Among the applied treatments, biochar did not show any recovery function, whereas CT treatments fully restored physiological parameters and growth performance in a concentration-dependent manner. Recycled hydroponic systems often lead to physiological decline in plants, which can be effectively counteracted by CT treatments. Full article

The continuous-cropping obstacles of Pogostemon cablin (patchouli) is severely constrained by autotoxic phenolic acids accumulated in the rhizosphere soil. Biochar adsorption and chemical oxidation are common remediation strategies; they often fail to simultaneously and efficiently remove phenolic allelochemicals while improving the soil micro-ecological environment. To address this issue, this study developed a novel biochar–urea peroxide composite particle (BC-UP). Batch degradation experiments and electron paramagnetic resonance (EPR) analysis confirmed the synergistic adsorption-oxidation function of BC-UP. A pot experiment demonstrated that application of BC-UP (5.0 g/kg) significantly alleviated phenolic acid stress. Specifically, BC-UP application significantly enhanced shoot biomass by 28.8% and root surface area by 49.3% compared to the phenolic acid-stressed treatment and concurrently reduced the total phenolic acid content in the rhizosphere soil by 37.3%. This growth promotion was accompanied by the enhanced accumulation of key bioactive compounds (volatile oils, pogostone, and patchouli alcohol). BC-UP amendment also improved key soil physicochemical properties (e.g., pH, and organic matter) and enhanced the activities of critical enzymes. Furthermore, BC-UP reshaped the microbial community, notably reducing the fungi-to-bacteria OTU ratio by 49.7% and enriching the relative abundance of Firmicutes and Nitrospirota but suppressing the Ascomycota phylum abundance. Redundancy analysis identified soil sucrase and catalase activity, total phenolic acid content, and Ascomycota abundance as key factors influencing patchouli biomass. In conclusion, BC-UP effectively mitigates phenolic acid stress through combined adsorption and radical oxidation, subsequently improving soil properties and restructuring the rhizosphere microbiome, offering a promising soil remediation strategy for patchouli and other medicinal crops. Full article

The article focuses on allelopathic interactions between plants. It presents the results of the effect of biological extracts from Solidago canadensis and Robinia pseudoacacia on seedlings of Lepidium sativum and Solidago canadensis. Solidago canadensis extracts inhibit the growth of Lepidium sativum, while Robinia pseudoacacia extracts stimulate the growth of Lepidium sativum. The application of Solidago canadensis extracts to Solidago canadensis seedlings showed signs of autotoxicity. Full article

Soil salinization and autotoxicity are major abiotic stresses constraining melon production. The ACE gene family (also known as HOTHEAD, HTH) encodes flavin-containing oxidoreductases involved in stress responses and RNA cache-mediated non-Mendelian inheritance. This study presents a comprehensive genome-wide analysis of the ACE/HTH gene family in melon through integrated bioinformatic and experimental approaches. We identified 14 CmACE genes encoding proteins of 457–595 amino acids. This gene family underwent significant expansion through tandem duplication events, particularly on chromosome 5. Phylogenetic analysis grouped these genes into three distinct clades with conserved gene structures and motif compositions. Promoter analysis identified abundant stress- and hormone-responsive cis-elements, with ABRE elements being predominant. Expression analyses revealed that multiple CmACE genes, including CmACE3, CmACE5, CmACE6 and CmACE14, were significantly upregulated under salt-alkali and autotoxicity stresses, showing distinct tissue-specific and time-dependent expression patterns. Notably, CmACE3 and CmACE6 were strongly induced under both stresses, while the tandemly duplicated pair CmACE6 and CmACE7 exhibited divergent expression patterns, suggesting functional specialization. Our findings provide the first comprehensive characterization of the CmACE gene family in melon, revealing its evolutionary history and stress-responsive regulation. These results not only offer valuable genetic resources for breeding stress-resistant melons but also lay a foundation for future research into the potential role of this conserved gene family in integrating stress adaptation with epigenetic regulatory pathways in crops. Full article

Continuous cropping of morel represents a crucial bottleneck that restricts the sustainable development of its industry. To explore the effects and mechanisms of crop rotations in alleviating continuous cropping obstacles, field experiments were conducted over two cropping years. With morel monoculture serving as the control (Control), four rotation patterns were established: tomato–morel (TM), pepper–morel (PM), watermelon–morel (WM), and cabbage–morel (CM). Soil physical and chemical properties, enzyme activities, phenolic acid substances, amino sugars, toxic metal contents, and morel yields were systematically measured. The soil quality index area (SQI-area) was employed for comprehensive evaluation. The results indicated that, in comparison to the control, rotation effectively mitigated soil salinization, optimized nutrient availability, and significantly decreased the accumulation of multiple auto-toxic phenolic acids (such as phthalic acid and benzoic acid) and toxic metals (As, Cd). All rotation treatments significantly enhanced the overall soil quality. Compared to the control, the SQI-area in rotation treatments increased by 25–137% in 2024 and 126–276% in 2025. Among these, the PM treatment exhibited the greatest increase. Furthermore, in both 2024 and 2025, the PM treatment exhibited the most substantial increase in yield. Specifically, it showed increases of 76% and 241% when compared to the control. In summary, crop rotations, particularly the pepper–morel rotation pattern, can effectively mitigate continuous cropping obstacles via multiple soil improvement mechanisms. This makes it an effective strategy for facilitating the sustainable production of morel. Full article

Continuous cropping obstacles (CCOs) lead to a decline in yield and quality under repeated cultivation in the same farmland. Notably, CCOs caused by fusarium wilt, autotoxicity, or imbalance in rhizosphere microbial communities reduce the productivity of watermelons (Citrullus lanatus). Considering the negative environmental impacts of conventional agrochemicals, it is necessary to evaluate the biocontrol efficiency of microorganisms. Therefore, this study aimed to investigate the biocontrol efficiency of Bacillus amyloliquefaciens strain PP19 against CCOs of watermelon so as to develop alternatives to agrochemicals. The inhibitory effect of PP19 on watermelon fusarium wilt was assessed through plate confrontation assays and field trials. The degradation and utilization of autotoxins by PP19 were examined via co-culture experiments. Additionally, 16S rRNA sequencing was employed to analyze the impact of PP19 on the rhizosphere soil microbial community of watermelon. Specifically, we analyzed the PP19 utilization of four phenolic autotoxins secreted by watermelon roots and assessed their effects on microbial diversity in the watermelon rhizosphere. Plant growth assays showed that PP19 improved the weight and quality of watermelon fruit. Although PP19 inhibited the growth of Fusarium oxysporum f. sp. niveum (Fon), the growth inhibitory effect was significantly enhanced by autotoxins produced by watermelon, including mixed phenolic, cinnamic, ferulic, and p-coumaric acids. Additionally, PP19 effectively degraded and utilized the autotoxins, and the autotoxins enhanced PP19’s swimming ability and biofilm formation. Moreover, PP19 treatment significantly enhanced the microbial diversity in watermelon rhizosphere, increased the number of beneficial bacterial genera, and decreased the number of pathogenic genera. Conclusively, these results suggest that B. amyloliquefaciens strain PP19 improves the resistance of watermelon to CCOs by effectively utilizing and degrading autotoxin, altering soil microbial community structure, and inhibiting Fon17 growth, resulting in improved fruit quality. Overall, PP19 possesses potential application as a biological control agent against CCOs in commercial watermelon cultivation. Full article

Dictyophora rubrovalvata is a soil-cultivated edible fungus with high economic and medicinal value, yet its continuous cultivation is frequently hindered by cropping obstacles. To elucidate the underlying ecological mechanisms, this study employed metagenomic sequencing and untargeted metabolomics (UHPLC–OE–MS) to analyze the changes in soil microbial communities and metabolite profiles under different continuous cropping treatments (CC0: Uncultivated; CC1: one cropping cycle; CC2: two cropping cycle; CC3: three cropping cycle.). Continuous cropping significantly decreased soil pH from 7.94 to 7.52 and available phosphorus (AP) from 213.69 mg/kg to 15.7 mg/kg, while increasing available nitrogen (AN) from 284.5 mg/kg to 886.33 mg/kg. The Shannon index of fungal communities rose from 3.15 to 4.55. Notably, the relative abundance of the beneficial bacterium Sphingomonas declined from 15.63% to 1.12%, whereas the pathogenic fungus Aspergillus increased from 0.06% to 3.06%. A total of 1408 secondary metabolites were detected, with 39 significantly upregulated and 416 downregulated in CC3 compared to CC0. Several autotoxic compounds, including ferulic acid, hydroxycinnamic acid derivatives, and jasmonic acid, were enriched and positively correlated with pathogenic fungi. These results suggest that continuous cropping may reshape the soil microecosystem by promoting autotoxic metabolite accumulation and pathogenic Microbial enrichment, thereby contributing to soil degradation and cropping obstacles. Full article

Continuous cropping poses a significant threat to sustainable pepper production by triggering soil degradation and growth inhibition, yet the role of root exudates in this process remains unclear. This study aimed to elucidate how continuous cropping duration (0, 1, 2, and 6 years) alters root exudate composition and drives rhizosphere feedback in green pepper. Pot experiments revealed that long-term continuous cropping (6 years) severely inhibited pepper growth, reducing photosynthetic rate (32.02%), chlorophyll content (12.26%), plant height (23.89%), and yield (42.37%). Critically, the relative abundance of 3,4-dimethylbenzaldehyde in root exudates increased progressively with cropping duration. Exogenous application of this compound or long-term monoculture extracts reduced soil pH and increased electrical conductivity, altered the rhizosphere microbial community (notably decreasing Proteobacteria abundance and fungal diversity while increasing Bacteroidota and Firmicutes), and significantly inhibited root development and vitality. Correlation analysis indicated that fungal communities were more responsive to soil property changes, while bacterial communities correlated more closely with root traits. This study demonstrates that the accumulation of specific root exudates, particularly 3,4-dimethylbenzaldehyde, is a key driver of continuous cropping obstacles in green pepper by disrupting rhizosphere microbial community structure and soil properties. This highlights the importance of managing root exudate dynamics, potentially through crop rotation or soil amendments, to mitigate these obstacles. Full article

β-ketoacyl CoA synthase (KCS) is a key enzyme in the synthesis of long-chain fatty acids. It affects plant stress resistance by regulating the chain length of fatty acid elongation products, the wax deposition in plant epidermis, and the formation of suberization layers. Through a comprehensive, genome-wide analysis, we identified members of the melon KCS (CmKCS) family and characterized their sequence features, phylogenetic relationships, and expression profiles under three abiotic stress conditions, employing bioinformatics tools and methods. Fifteen CmKCSs were identified in the melon genome and found to be unevenly distributed across eight chromosomes. The subcellular localization of most members is located on the cytoplasmic membrane and chloroplasts. The CmKCS family amplifies its members in a tandem repeat manner, which is more closely related to the cucumber KCS and has similar gene functions. Subfamilies I, IV, and VI exhibit variations in conserved domain sequences, which may indicate specific functional differentiation. The promoter region harbors various cis-acting elements related to plant hormones and abiotic stress responses. Among these, the most abundant are elements responsive to abscisic acid, methyl jasmonate, salicylic acid, and anaerobic induction. CmKCS5, CmKCS6, CmKCS10, and CmKCS12 showed high expression in autotoxicity, saline-alkali stress, and microplastic exposure environments. These four CmKCSs may play important roles in melon development and stress response. In conclusion, this study provides a comprehensive analysis of the CmKCS gene family, revealing its potential roles in melon’s response to abiotic stresses and laying a foundation for further functional characterization of these genes in stress tolerance mechanisms. Full article

Daunorubicin (DNR) is an anthracycline antibiotic originating from soil-dwelling actinobacteria extensively used to treat malignant tumors. Over the decades, extensive attempts were made to enhance the production of anthracyclines by introducing genetic modifications and mutations in combination with media optimization, but the target production levels remain comparatively low. Developing an appropriate culture medium to maximize the yield of DNR and preventing autotoxicity for the producing organism remains a challenge. Our prospective review sheds light on a method involving perturbation that enhances the precursors to regulate the type II PKS pathway, enhancing cells’ capacity to increase secondary metabolite production. The suggested method also entails the preparation of culture media for the cultivation of Streptomyces sp. and enhanced yield of DNR, as well as making it inactive with iron or its reduced forms following efflux from the producer. The iron or iron–DNR complex is encapsulated by oleic acid or lipid micelle layers in the culture media, finally resulting in the generated inactive DNR and the DNR–iron–oil complex. This idea has the potential to protect the producer organism from autotoxicity and prevent the inhibition of metabolite production. The approach of substituting sugar with oil in culture media has a dual role wherein it promotes Streptomyces growth by utilizing lipids as an energy source and encapsulating the generated DNR–iron complex in the medium. In this review, we discussed aspects like anthracycline producers, biosynthesis pathways, and gene regulation; side effects of DNR; mechanisms for autotoxicity evasion; and culture media components for the enhancement of DNR production in Streptomyces sp. We anticipate that our work will help researchers working with secondary metabolites production and decipher a methodology that would enhance DNR yield and facilitate the extraction of the resulting DNR by lowering costs in large-scale fermentation. Full article

Phenolic allelochemicals from root exudates dominate rhizosphere formation, lead to autotoxicity in plants subjected to continuous monoculture (CM) stress and induce the emergence of replant disease. However, the regulatory mechanisms governing the transport of phenolics from plant roots to the rhizosphere remain poorly understood. A potential phenolic efflux transporter from Rehmannia glutinosa, designated RgMATE35, has been preliminarily characterized. The objective of this study was to elucidate the molecular function of RgMATE35 in the secretion of phenolics and to investigate its role in the development of plant replant disease using quantitative real-time PCR (qRT-PCR), genetic transformation, HPLC-Q-TOF-MS and other analytical techniques. A tissue expression pattern analysis of RgMATE35 revealed that it is highly expressed in plant roots. Transient expression analysis confirmed the localization of the protein in plasma membranes. An assessment of the transport activity of RgMATE35 in Xenopus oocytes indicated that it plays a role in facilitating the efflux of labeled ferulic acid ([²H₃]-FA) and trans-p-coumaric acid [²H₆]-pCA. The results of functional studies in R. glutinosa demonstrated that RgMATE35 positively mediates the secretion of FA and pCA from plant roots into the rhizosphere. A molecular and physiological analysis of RgMATE35 transgenic plants subjected to CM stress revealed that the overexpression or repression of RgMATE35 resulted in notable changes in the degree of autotoxic injury in plants. These findings demonstrate that RgMATE35 plays a positive role in the development of replant disease through the secretion of phenolic acids from plant roots. They also provide a fundamental framework for elucidating the molecular regulatory mechanism through which MATEs regulate replant disease through the root secretion of allelochemicals. Full article