Search Results (161)

Northern corn leaf blight (NCLB), caused by Exserohilum turcicum, is a major foliar disease of maize worldwide. To develop sustainable alternatives that reduce chemical products, we evaluated Bacillus velezensis EM-A8 (GenBank accession number OL704805) as a biocontrol agent under greenhouse and field conditions. The aims of this study were as follows: (i) characterize phytohormone production in two formulations containing the BCA; (ii) assess the influence of the BCA on plant biomass and yield; (iii) compare the efficacy of both formulations in controlling NCLB under field conditions; and (iv) determine whether the treatments affected salicylic acid and phenolic compound levels in maize tissues. The strain synthesized a broad spectrum of phytohormones, including salicylic acid, indoleacetic acid, indolebutyric acid, jasmonic acid, abscisic acid and gibberellic acid, as well as cytokinins such as kinetin, zeatin, and 6-benzylaminopurine. Foliar application increased maize dry biomass by 30%. In field trials, both formulations effectively suppressed NCLB, reducing the number of symptomatic leaves by 25–50% compared with controls. Furthermore, treated plants exhibited yield increases exceeding 1000 kg/ha. These findings demonstrate that B. velezensis EM-A8 provides effective biocontrol of E. turcicum while simultaneously enhancing maize growth and yield under field conditions. Future work should aim to scale up the use of B. velezensis EM-A8 in integrated pest management programs and evaluate its long-term impact on soil microbiota, plant health, and yield sustainability. Full article

The conformational landscape of 3-indoleacetamide, a key intermediate in plant hormone biosynthesis, has been comprehensively investigated using state-of-the-art laser-ablation chirped-pulse Fourier transform microwave (LA-CP-FTMW) and laser-ablation molecular beam Fourier transform microwave (LA-MB-FTMW) spectroscopy. Remarkably, 3-indoleacetamide exhibits unprecedented conformational rigidity within the tryptophan-derived molecule family, displaying only a single stable conformer characterized by distinctive a-, b-, and c-type rotational transitions. This singular conformational behavior contrasts dramatically with the structural flexibility observed in closely related tryptophan derivatives such as tryptophan, serotonin, tryptamine, and 3-indoleacetic acid. The unique structural constraint imposed by the acetamide functional group provides unprecedented insights into the molecular determinants governing the distinct biological roles of tryptophan-derived compounds. This work establishes a potential correlation between conformational flexibility and biological function, from neurotransmission to plant hormone regulation, offering new perspectives on structure-activity relationships in bioactive natural products. Full article

Phoebe bournei is an important economic tree species in China, its large-scale propagation is limited by the difficulty of adventitious root (AR) formation in cuttings. In this study, morphological, physiological, and transcriptomic analyses were conducted to investigate the process of AR formation in P. bournei. The results showed that ARs mainly originated from callus tissue. During AR formation, soluble sugar and soluble protein contents changed significantly. Malondialdehyde (MDA) and oxygen free radicals (OFRs) peaked at first sampling stage (PB0), while the activities of polyphenol oxidase (PPO) and indoleacetic acid oxidase (IAAO) exhibited similar patterns. Lignin content increased during callus induction stage, whereas phenolic content continuously declined throughout rooting. Endogenous hormone levels also changed markedly, and Orthogonal partial least squares discriminant analysis (OPLS-DA) analysis indicated that indole-3-acetic acid (IAA) and abscisic acid (ABA) played dominant roles in this process. KEGG enrichment analysis revealed significant enrichment of the phenylpropanoid biosynthesis pathway in all three comparison groups. A total of 48 differentially expressed genes (DEGs) were enriched in plant hormone signal transduction pathways, with 22 and 14 genes associated with IAA and ABA signaling, respectively. Weighted gene co-expression network analysis (WGCNA) further identified two hub modules related to IAA and ABA contents, including eight hub genes such as D6PKL1 and ISTL1. Correlation analysis revealed that the hub genes D6PKL1 and HSP were significantly positively correlated with IAA4 in the IAA signaling pathway. Overall, this study provides new insights into the mechanisms underlying AR formation in P. bournei cuttings and offers a theoretical basis for optimizing its clonal propagation system. Full article

Following new trends in green development, many studies have focused on the high-value utilization of fish resources through green biological processes. This study innovatively introduced a one-step process of mixed strain–enzyme synergy (MES) with which to prepare tilapia hydrolysates and explored the synergistic effects of strains and enzymes on both the protein hydrolysis process and its products’ characteristics via comparative experiments. Further, soybean was used as a model crop to verify the agronomic effects of the hydrolysates. The addition of exogenous papain increased hydrolysis by 31.94% compared to the fermentation-only group. Peptides and amino acids contents in the mixed strains were higher than those in the single fermentation process (p < 0.05), while 8.46 mg/L of indoleacetic acid was produced through fermentation. Hydrolysates promoted the growth of lateral roots in soybean seedlings (p < 0.05) via the use of a 2500-fold dilution of the biostimulant, increasing the root area and stem length and reducing the sugar content of soybean seedlings by 1.59-, 1.44- and 1.69-fold compared to those in Hoagland’s nutrient solution. These results lay a foundation for the biological preparation of biostimulants for hydroponic vegetables through the utilization of fish waste resources, aligning with green development goals. Full article

Subsurface drip irrigation can improve crop water and fertilizer use efficiency, but it can cause soil hypoxia. We report on experiments performed in Aksu Prefecture, Xinjiang (41°17′ N latitude, 80°17′ E longitude), from April 2023 to October 2024 using oxygenated drip irrigation from the surface to 50 cm depth in an apple (Malus pumila Mill.) orchard, to examine the effects of drip irrigation on inter-root hypoxia, tree growth, fruit quality, and yield. Compared with surface oxygenated drip irrigation (CK), irrigating at 10 and 30 cm increased soil water content in the root system, elevated gibberellin, zeatin ribosides, and indoleacetic acid contents and reduced abscisic acid contents in new shoot tips. Compared with CK, branch and leaf nitrogen, phosphorus, and potassium contents were increased with irrigation at depths of 10 and 30 cm. The leaf nitrogen (N), phosphorus (P), and potassium (K) contents were increased by 18.03%, 22.42%, and 16.63%, respectively, in the treatment with a burial depth of 30 cm. Among treatments, irrigation at 30 cm produced the highest average daily plant water potential, and irrigation at 50 cm was the lowest. Maximum leaf soil–plant analysis development (SPAD) values occurred when irrigated at 30 cm, and minimum values occurred at 50 cm. For both years, the largest range of light flux utilization occurred when irrigated at 30 cm and the lowest when irrigated at 50 cm. Significant correlations between indoleacetic acid (IAA), total gibberellin (GA), zeatin riboside (ZRs), leaf N content, leaf K content, plant water potential (PWP), net photosynthetic rate (Pn), SPAD, and apple yield were determined by partial mantel analysis. A significant correlation was found between abscisic acid (ABA), IAA, GA, leaf P and K content, and apple quality. Principal component analysis revealed a burial depth of 30 cm had the highest principal component composite score, indicating that this burial depth, and oxygenation and fertilization regime most favored apple growth, yield, and quality. Full article

Investigating the physiological responses and resistance mechanisms in plants under drought stress provides critical insights for optimizing irrigation water utilization efficiency and promoting the development of irrigation science. In this study, cotton seedlings were cultivated in a light incubator. Three drought stress levels were applied: mild (M1, 50–55% field moisture), moderate (M2, 45–50%), and severe (M3, 40–45%). Transcriptome analysis was performed under mild and severe stress. The results revealed that differentially expressed genes (DEGs) related to proline degradation were down-regulated and proline content increased in cotton. Under different stress treatments, cotton exhibited a stress-intensity-dependent regulation of carbohydrate metabolism and soluble sugar content decreased and then increased. And the malondialdehyde content analysis revealed a dose-dependent relationship between stress intensity and membrane lipid peroxidation. Stress activated the antioxidant system, leading to the down-regulation of DEGs for reactive oxygen species production in the mitogen-activated protein kinase (MAPK) signaling pathway. Concurrently, superoxide dismutase activity and peroxidase content increased to mitigate oxidative damage. Meanwhile, the photosynthetic performance of cotton seedlings was inhibited. Chlorophyll content, stomatal conductance, the net photosynthetic rate, the transpiration rate and water use efficiency were significantly reduced; intercellular carbon dioxide concentration and leaf stomatal limitation value increased. But photosynthesis genes (e.g., PSBO (oxygen-evolving enhancer protein 1), RBCS (ribulose bisphosphate carboxylase small chain), and FBA2 (fructose-bisphosphate aldolase 1)) in cotton were up-regulated to coordinate the photosynthetic process. Furthermore, cotton seedlings differentially regulated key biosynthesis and signaling components of phytohormonal pathways including abscisic acid, indoleacetic acid and gibberellin. This study elucidates the significant gene expression of drought-responsive transcriptional networks and relevant physiological response in cotton seedlings and offers a theoretical basis for developing water-saving irrigation strategies. Full article

Kiwifruit (Actinidia spp.) is a globally important economic fruit with high nutritional value. Fruit peelability, defined as the mechanical ease of separating the peel from the fruit flesh, is a critical quality trait influencing consumer experience and market competitiveness and has emerged as a critical breeding target in fruit crop improvement programs. The present review systematically synthesized existing studies on kiwifruit peelability, and focused on its evolutionary trajectory, genotypic divergence, quantitative evaluation, possible underlying mechanisms, and artificial manipulation strategies. Kiwifruit peelability research has advanced from early exploratory studies in New Zealand (2010s) to systematic investigations in China (2020s), with milestones including the development of evaluation metrics and the identification of genetic resources. Genotypic variation exists among kiwifruit genera. Several Actinidia eriantha accessions and the novel Actinidia longicarpa cultivar ‘Guifei’ exhibit superior peelability, whereas most commercial Actinidia chinensis and Actinidia deliciosa cultivars exhibit poor peelability. Quantitative evaluation highlights the need for standardized metrics, with “skin-flesh adhesion force” and “peel toughness” proposed as robust, instrument-quantifiable indicators to minimize operational variability. Mechanistically, peelability is speculated to be governed by cell wall polysaccharide metabolism and phytohormone signaling networks. Pectin degradation and differential distribution during fruit development form critical “peeling zones”, whereas ethylene, abscisic acid, and indoleacetic acid may regulate cell wall remodeling and softening, collectively influencing skin-flesh adhesion. Owing to the scarcity of easy-to-peel kiwifruit cultivars, artificial manipulation methods, including manual peeling benchmarking, lye treatment, and thermal peeling, can be employed to further optimize kiwifruit peelability. Currently, shortcomings include incomplete genotype-phenotype characterization, limited availability of easy-peeling germplasms, and a fragmented understanding of the underlying mechanisms. Future research should focus on methodological innovation, germplasm development, and the elucidation of relevant mechanisms. Full article

The role of rhizosphere bacteria in facilitating plant invasion is increasingly acknowledged, yet the influence of specific microbial functional traits remains insufficiently understood. This study addresses this gap by isolating two bacterial strains, Bacillus sp. ScRB44 and Pseudomonas sp. ScRB22, from the rhizosphere of the invasive weed Solidago canadensis. We assessed their nitrogen utilization capacity and indoleacetic acid (IAA) production capabilities to evaluate their ecological functions. Our three-stage experimental design encompassed strain promotion, nutrient stress, and competition phases. Bacillus sp. ScRB44 demonstrated robust IAA production and significantly improved the nitrogen utilization efficiency, significantly enhancing S. canadensis growth, especially under nutrient-poor conditions, and promoting a shift in biomass allocation toward the roots, thereby conferring a competitive advantage over native species. Conversely, Pseudomonas sp. ScRB22 exhibited limited functional activity and a negligible impact on plant performance. These findings underscore that the ecological impact of rhizosphere bacteria on invasive weeds is closely linked to their specific growth-promoting functions. By enhancing stress adaptation and optimizing resource allocation, certain microorganisms may facilitate the establishment of invasive weeds in adverse environments. This study highlights the significance of microbial functional traits in invasion ecology and suggests novel approaches for microbiome-based invasive weed management, with potential applications in agricultural soil health improvement and ecological restoration. Full article

Camellia azalea is an endemic species within the genus Camellia that exhibits the trait of summer flowering, which is of significant ornamental and research value. Nevertheless, research on the regulatory mechanisms of flower formation in C. azalea is still limited, so in this study, transcriptome sequencing and analysis of endogenous hormone contents were conducted at three distinct growth stages: floral induction, floral organ maturation, and anthesis. Illumina sequencing yielded a total of 20,643 high-quality unigenes. Comparative analyses of representative samples from the three growth stages identified 6681, 1925, and 8400 differentially expressed genes (DEGs), respectively. These DEGs were further analyzed for functional enrichment using the GO and KEGG databases. Additionally, core genes from each flowering pathway underwent expression pattern analysis and network diagram construction. This revealed that the flower development process in C. azalea is linked to the specific expression of the genes involved in the photoperiod, temperature, and autonomous pathways and is subject to comprehensive regulation by multiple pathways. Further analysis of the dynamic trends of five endogenous hormone contents and plant hormone signal transduction genes revealed significant differences in the requirements of endogenous hormones, such as gibberellins and indoleacetic acid, by C. azalea at distinct growth stages. Additionally, the majority of genes on the phytohormone signal transduction pathway demonstrated a high correlation with the changes in the contents of each hormone. The present study integrates physiological and molecular approaches to identify key genes and metabolic pathways that regulate the summer flowering of C. azalea, thereby laying a theoretical foundation for further investigations into its flowering mechanism and related functional genes. Full article

Oncidium has an important market value, with important high-grade cut orchids and potted flowers on the flower market. In the Oncidium cut flowers production industry, there is a common phenomenon that the development of vegetative buds disrupts the normal generation cycle of the inflorescence induction, so-called “bud jumping”. In this study, vegetative bud differentiation and flower bud differentiation were divided into three stages, namely, the initial stage of differentiation, the leaf primordial/flower primordial differentiation stage, and the late stage of leaf bud/flower bud differentiation, as observed by paraffin sectioning. Secondly, we analyzed the differences between the vegetative buds of “bud jumping” plants and the flower buds of normal flowering plants by transcriptome sequencing. The transcriptome analysis results revealed significant differences among plant signaling pathways, particularly in gibberellins, auxins, and cytokinins, which play important roles in this phenomenon’s formation. In conjunction with the transcriptome analysis, the researchers conducted field experiments by applying plant growth regulators on the newborn pseudobulb of young Oncidium plants measuring approximately 49 mm in length. The results showed that the treatment groups of 100 mg/L of gibberellic acid (GA₃) and 100 mg/L GA₃ + 10 mg/L 6-Benziladenine (6-BA) exhibited the highest rate of flower bud differentiation instead of the least “bud jumping” phenomenon, and the “bud jumping” phenomenon was significantly reduced under 25 mg/L, 50 mg/L, and 75 mg/L 3-indoleacetic acid (IAA) treatments. The application of exogenous gibberellins, cytokinins, and auxins can effectively reduce the occurrence of “bud jumping”. Full article

Despite chemical exchange often serving as the first step in plant–microbe interactions, the specialized chemical metabolites produced by grass–Epichloë endophyte symbiosis as mediators of host growth, nutrient acquisition, and modulators of the rhizosphere community under low-nitrogen conditions are areas lacking in knowledge. In this study, we investigated the plant growth-promoting effects of the Epichloë endophyte strain and identified the growth of the Epichloë strain under different types of nitrogen source treatments. In addition to the in vitro test, we evaluated growth performance for Epichloë endophyte–infected plants (E+) and Epichloë endophyte–free plants (E−) in a pot trial under 0.01 mol/L urea treatment. Seedlings from E+ and E− groups were collected to analyze the plant bacterial microbiome and root metabolites. The E. gansuensis endophyte strain was found not to produce indoleacetic acid (IAA), pectinase, or contain ferritin. The nitrogenase gene, essential for nitrogen fixation, was also absent. These results suggest that E. gansuensis endophyte strains themselves do not contain attributes to promote plant growth. Concerning N fertilization, it was observed an increase in the colony diameter of E. gansuensis strain was observed only in the NO₃⁻-N (NN) treatment, while inhibition was observed in the urea-N (UN) treatment. E. gansuensis endophyte symbiosis significantly increased tiller number and plant dry weight. Overall, our results suggest that the E+ plants had more root forks and greater average root diameter compared to E− plants under the UN treatment. In a pot experiment using UN, data from 16S rRNA amplicon sequencing revealed that E. gansuensis endophyte infection significantly altered the bacterial community composition in shoot and root, and significantly increased Shannon (p < 0.001) and Chao 1 (p < 0.01) indexes. The relative abundance of Acidobacteriota, Actinomycetota, Cyanobacteriota, Fibrobacterota, Myxococcota, and Patescibacteria in the shoot, and Cyanobacteriota, Pseudomonadota, and Verrucomicrobiota in the root were significantly increased by E. gansuensis endophyte infection. Similarly, E. gansuensis endophyte symbiosis shifted the metabolite composition of the host plants, with the E+ plants showing a higher number of metabolites than the E− plants. In addition, co-metabolism network analysis revealed that the positive relevance between exudates and microorganisms in the root of the E+ plants is higher than that of the E− plants. These findings provide valuable insights into the knowledge of the effects of the symbiotic relationship between host plants and Epichloë endophyte on interspecific interactions of plant microbiome, beneficial for harnessing endophytic symbiosis, promoting plant growth. Full article

The Orchidaceae family is of significant decorative, pharmaceutical, alimentary, and cultural importance worldwide. This family is very vulnerable due to illegal looting, habitat destruction, and climate change. The development of new hybrids helps meet the demand for specimens that possess outstanding appearance, fragrance, and resistance characteristics and may reduce illegal looting. The objective of this research was to investigate the in vitro propagation of the hybrid Rhyncattleanthe Queen Bee JLA 1 (Rth. Queen Bee JLA 1). Shoot induction was performed with germinated seedlings that were 1 cm in length on semi-solid MS medium with different 6-Benzylaminopurine (BAP), 1-Naphthaleneacetic acid (NAA), 3-Indoleacetic acid (IAA), and 3-indolebutyric acid (IBA) concentrations. Micropropagation was conducted using a temporary immersion system (TIS), a liquid continuous immersion system (CIS), and a conventional semi-solid system (SSS). Afterwards, all regenerated seedlings underwent an acclimatization stage. The highest numbers of shoots (7.04) and leaves (14.28) were obtained with the combination of 1.5 mg L⁻¹ BAP and 0.4 mg L⁻¹ NAA, while the addition of 0.4 mg L⁻¹ IBA in combination with 1.5 mg L⁻¹ BAP enhanced the length of stems (2.12 cm) and leaves (1.88 cm). TIS produced the highest number of shoots (15.68), leaves (22.92), stem length (5.94 cm), and number of leaves (3.50) in seedlings analyzed. The combination of growth regulators BAP and NAA together with the temporary immersion system influenced both the development of the vitroplants and their vegetative development after acclimatization of the hybrid Rth. Queen Bee JLA1 orchid. Full article

Sweet potato (Ipomoea batatas (L.) Lam.), as an important crop, is rich in polyphenols, vitamins, minerals, and other nutrients in its roots and leaves and is gradually gaining popularity. The use of endophytic bacteria to improve the quality of sweet potato can protect the environment and effectively promote the sustainable development of the sweet potato industry. In this study, 12 strains of endophytic bacteria were isolated from sweet potato. Through nitrogen fixation, phosphorus solubilization, indoleacetic acid production, siderophore production, ACC deaminase production, and carboxymethyl cellulose production, three strains with multiple biological activities were screened out. Among them, MEPW12 had the most plant growth-promoting functions. In addition, MEPW12 promoted host chlorophyll accumulation and inhibited pathogen growth and colonization in sweet potato roots and can utilize various carbon sources and salts for growth. It can also grow in extreme environments of high salt and weak acid. MEPW12 was identified as Bacillus amyloliquefaciens with a genome size of 3,928,046 bp and a GC content of 46.59%. After the annotation of multiple databases, it was found that MEPW12 had multiple enzymatic activities and metabolic potential. Comparative genomics and pan-genomics analyses revealed that other Bacillus sp. strains of MEPW12 have similar functions. However, due to adaptation to different growth environments, there are still genomic differences and changes. Inoculation with MEPW12 induced the high expression of IbGH3.10, IbERF1, and other genes, thereby promoting the growth of sweet potatoes. Bacillus amyloliquefaciens strain MEPW12 is a sweet potato endophyte with multiple growth-promoting functions, which can promote the growth of sweet potato seedlings. This study provides new microbial resources for developing microbial agents and improving the quality of sweet potatoes. Full article

Plant regulators, such as auxins, modulate the synthesis of specialized metabolites and aid in the bioprospection of molecules. Annona emarginata is known to produce antifungal alkaloids and serves as a rootstock for Annona atemoya. This study evaluated the effects of indoleacetic acid (IAA), indolebutyric acid (IBA), and naphthaleneacetic acid (NAA) applications on the accumulation of alkaloids in ungrafted A. emarginata and grafted with A. atemoya. Total alkaloids were analyzed by spectrophotometry, and alkaloid profiles were analyzed by DI-MS at 8, 14, and 20 days after treatments (DAT). The results indicated that IAA and NAA had the strongest effects on increasing the synthesis of alkaloids in the roots of ungrafted seedlings. In grafted plants, IBA had a more pronounced effect on roots; however, at final evaluation, all three auxins had an impact on both roots and leaves. Chemometric analysis revealed that auxins also altered the alkaloid composition in both seedling types. Nineteen alkaloids were identified regardless of treatment and harvest time. Eight alkaloids were identified for the first time in A. emarginata and nine were identified in A. atemoya. The main alkaloids found in ungrafted seedlings treated with IAA, IBA, and NAA were liriodenine and lanuginosine. In grafted seedlings, liriodenine and reticuline were the primary alkaloids found in roots, whereas liriodenine, lanuginosine, and reticuline were significantly present in leaves. The use of auxins to enhance alkaloid biosynthesis demonstrates their potential for bioprospection and the development of crops tolerant to biotic stress. Full article

Tryptophan hydroxylase (Tph), the rate-limiting enzyme of serotonin (5-hydroxytryptophan; 5-HT) synthesis, exists in two isoforms, Tph1 and Tph2. Tph1 upregulates peripheral 5-HT synthesis and blood 5-HT levels, whereas Tph2 upregulates brain 5-HT synthesis. Here, we show that plasma and brain levels of tryptophan and its metabolites, including 5-HT, 5-hydroxy indoleacetic acid, indolepropionic acid, indole-3-acetic acid, kynurenine, and xanthurenic acid, are decreased in young (8-week-old) Tph1-mutant mice compared with age-matched wild-type mice. In older (7-month-old) Tph1-mutants, the decreases in tryptophan and its metabolites outside the 5-HT pathway were diminished. Although single-housed Tph1 mutants displayed age-related alterations in food intake, body weight, and plasma FGF21 levels, blood glucose levels were lower in both young and older Tph1 mutants compared with age-matched wild-type mice. These findings suggest that Tph1 regulates tryptophan and its metabolites in the plasma and brain, as well as blood glucose homeostasis. Full article