Hemipteran insects feed on phloem sap and excrete substantial amounts of honeydew that accumulate on plant leaves. Rich in carbohydrates and microbes, honeydew is known to mediate ecological interactions between insect pests and their natural enemies. However, the mechanisms and ecological consequences of honeydew-associated microbes in plant-herbivore interactions have not been fully elucidated. In this study, we investigated the impact of honeydew deposition by the mealybug Phenacoccus solenopsis on herbivore fitness and the underlying mechanisms. Application of crude honeydew to cotton plants reduced weight gain in both P. solenopsis and Helicoverpa armigera and inhibited phloem ingestion by P. solenopsis. While sterilized honeydew also suppressed the growth of H. armigera, it did not affect P. solenopsis. Both crude and sterilized honeydew induced jasmonic acid (JA)- and salicylic acid (SA)-dependent defense responses and promoted SA accumulation in cotton. To evaluate the contribution of honeydew-associated microbes, we isolated and identified three bacterial genera, Acinetobacter, Bacillus, and Staphylococcus, from honeydew, using 16S rRNA sequencing. Exogenous application of Acinetobacter or Bacillus to cotton leaves suppressed weight gain in both herbivore species and reduced phloem ingestion by P. solenopsis. Additionally, each bacterial isolate activated the expression of JA- and SA-responsive genes and enhanced the accumulation of both hormones. These results demonstrate that honeydew-associated microbes play a key role in plant-herbivore interactions by activating plant defenses. Our study reveals that hemipteran honeydew microbes can function as exogenous elicitors of plant resistance against herbivorous insects.

Pseudomonas syringae functions as a model phytopathogen causing numerous crop diseases, resulting in substantial economic losses in global agriculture. Presently, management of P. syringae predominantly depends on chemical pesticides; however, their prolonged application has contributed to escalating resistance and environmental contamination, highlighting urgent requirement for sustainable biological control approaches. In this review, we examine recent advances in the utilization and mechanistic understanding of natural products derived from plants, animals, and microorganisms for the control of P. syringae. Plant-derived compounds—including flavonoids, terpenoids, and alkaloids—inhibit P. syringae infection by targeting the bacterial type III secretion system (T3SS), disrupting cell membrane integrity, promoting reactive oxygen species (ROS) accumulation, and activating plant immune signaling pathways such as salicylic acid (SA) and jasmonic acid (JA) cascades. Animal-derived substances, such as chitosan, propolis, and antimicrobial peptides, primarily exert antibacterial effects through membrane disruption and immune system stimulation. Microbial-derived natural products contribute to synergistic disease suppression by modulating host immunity and interfering with the pathogen’s quorum sensing mechanisms. Evidence indicates that these natural products possess multi-target antimicrobial properties, offering a rich repository of candidate molecules, such as baicalein, lignans, and carvacrol, for the development of eco-friendly antibacterial agents. Future investigations should focus on detailed characterization of these bioactive compounds and their specific disease targets, optimization of extraction methodologies to improve stability and bioavailability, and comprehensive assessment of environmental safety to advance the industrial implementation of sustainable biocontrol strategies

Abstract The delayed flower bud opening of Lonicera japonica ‘Huajin 6’ extends its harvest window and enhances agricultural value, yet the underlying molecular basis remains unclear. Here, we assembled a chromosome-level genome of ‘Huajin 6’ using PacBio sequencing and high-throughput chromosome conformation capture (Hi-C) scaffolding (824.72 Mb, scaffold N50 = 91.2 Mb). Comparative genomic analyses revealed a subfamily-specific contraction of lipoxygenase (LOX) genes, particularly within the 9-LOX clade, which is associated with a reduced jasmonate biosynthetic capacity during floral development. Transcriptomic and hormone profiling showed coordinated suppression of jasmonic acid (JA) biosynthesis-related genes and a marked reduction of JA and its bioactive derivatives during the transition from the complete white stage to flower opening. A JA-responsive co-expression module enriched in cell wall modification genes exhibited attenuated activation in ‘Huajin 6’. Functional assays further demonstrated that exogenous JA restored timely flower bud opening in both ‘Huajin 6’ and L. macranthoides, while heterologous expression of Lonicera LOX genes enhanced jasmonate accumulation in Arabidopsis. Together, these findings are consistent with a jasmonate threshold model in which LOX gene contraction constrains JA accumulation during floral transition, contributing to delayed flower bud opening and highlighting how genome structural variation influences hormone-dependent flowering dynamics.

White-flowered alfalfa (Medicago sativa L.) persisting in Qinghai–Tibet Plateau’s saline–alkali habitats provides a unique model to explore floral color polymorphism-linked ecological adaptation. We systematically compared phenotypic, physiological, transcriptomic, and metabolomic profiles of white-flowered (WF) and purple-flowered (PF) alfalfa under high-altitude cold/saline–alkali field conditions (three biological replicates; Student’s t-test). WF showed a significant growth-defense trade-off: flower size and chlorophyll a content decreased by 18.9% and 46.0%, with reduced gibberellin levels, while jasmonic acid (36.3%), proline (51.5%), antioxidant enzyme activities, total flavonoids (17.7%), and condensed tannins (18.2%) were significantly increased (p < 0.001). Multi-omics analysis revealed phenylpropanoid pathway reprogramming (suppressed anthocyanin biosynthesis, precursor accumulation) and coordinated hormone signaling (jasmonic acid activation, salicylic acid inhibition). Our findings confirm the white-flower trait is not an isolated mutation. It is a key component of a coordinated adaptive syndrome, mediated by metabolic reprogramming and hormonal crosstalk. These results provide theoretical and technical support for breeding stress-resistant alfalfa varieties suitable for marginal land cultivation.

Jasmonates influence carotenoids biosynthesis, the pigments responsible for tomato fruit coloration, but their effect on carotenoids synthesis remains controversial. Lycopene is the predominant carotenoid in ripe tomato fruits, accounting for more than 90% of the total carotenoid content in the fruit. Our study clarified this paradox by demonstrating that methyl jasmonate (MeJA) affects post-harvest tomato lycopene accumulation differently depending on light conditions and we identified SlPIF1a as the central regulatory factor mediating this light-JA crosstalk. In light, MeJA enhances lycopene synthesis by directly activating the expression of the SlPSY1 gene through the SlMYC2 transcription factor. SlMYC2 also inhibits the expression of SlPIF1a, encoding a negative regulator of light signal that degrades in light and accumulates in darkness. In dark conditions, the accumulated SlPIF1a interacts with SlMYC2 inhibiting its activation on SlPSY1 expression. Additionally, the MeJA-induced acetyltransferase SlNATA1 interacts with and acetylates SlPIF1a, enhancing its repression on SlPSY1. Our research uncovers a new mechanism for the dual regulation of lycopene synthesis by jasmonic acid under different light conditions.

This review highlights endophyte occurrence and diversity, mechanisms, signaling crosstalks, and innovative coating applications, positioning endophytes as eco-friendly tools bridging fundamental research and practical crop protection in horticultural crops. Endophytes are microorganisms that asymptomatically reside in plant tissues proving to be valuable partners in the realm of sustainable horticultural disease management. Their prevalence and diversity on horticultural crops indicate that there is a large pool of such microbial taxa with underused potential for promoting plant health. These endophytes use a variety of mechanisms in their fight against pathogens, including direct antagonism, niche and nutrient competition, and triggering of host defense mechanisms. Signaling crosstalk of the endophytes with the host plants can reprogram pathways like jasmonic acid, salicylic acid, and ethylene, leading to primed immunity and enhanced stress tolerance. The creation of enzymes (chitinase, glucanase) and bioactive metabolites is the main mechanism of pathogen growth suppression, while antimicrobial compounds and secondary metabolites are aimed at defense. Recent advances point out the promising use of endophytic formulations as bio-coatings on fruits to limit their post-harvest diseases, thus making the endophytic concept an eco-friendly substitute for synthetic chemicals. Advancements in the development and commercialization of endophyte-based coating materials demonstrate that they hold much promise as a low-cost and environmentally benign disease management strategy for horticultural industries.The aim of this review is to summarize recent insights into the diversity, molecular and biochemical mechanisms of action against pathogens, and translational potential of the metabolites from endophytes. It also calls attention to the endophytic coating as a new type of endophyte application that represents a bridge between basic research and an actual commercial coating. Taken collectively, this knowledge places endophytes as attractive parts of eco-sound, biologically initiated system of crop protection.

Medicago sativa is one of the world’s most important forage plants, possessing strong nitrogen-fixing and regrowth capabilities. Promoting its growth not only enhances stress resistance but also reduces the use of chemical fertilizers. The value of Centella asiatica is primarily reflected in its medicinal properties. Currently, endophytic fungal resources of C. asiatica are scarce, and their potential to promote medicinal components and the underlying mechanisms remains unclear. This study employed DNA extraction techniques to isolate and identify endophytic fungi from different parts of C. asiatica. We systematically analyzed the plant growth-promoting traits of endophytic fungi. After screening for the optimal strain and inoculating it into Medicago sativa, we elucidated the mechanisms underlying its growth-promoting effect using metabolomic sequencing. Research findings: A total of 18 endophytic fungal strains were isolated, belonging to 12 genera. Among them, five indole-3-acetic acid (IAA) strains were identified, with strain J4 demonstrating the highest IAA production (17.157 mg·L−1). The J4 strain has iron-transporting carrier activity, while 15 strains exhibit nitrogen-fixing activity. Inoculation with the Plectosphaerella plurivora strain significantly increases M. sativa’s germination rate, fresh weight, dry weight, and plant height. Metabolomic analysis indicates that P. plurivora may promote anthocyanin and jasmonic acid accumulation by regulating pathways such as flavonoid biosynthesis and pyrimidine metabolism, thereby promoting growth. This study reveals the mechanism by which endophytic fungi enhance M. sativa growth at the metabolomic level. This study reveals the growth-promoting mechanism of endophytic fungi in M. sativa from a metabolomic perspective, providing a theoretical basis for increasing forage yield and offering new insights into sustainable agricultural development.

Osmanthus fragrans is a well-known ornamental tree species for its pleasing floral fragrance. Linalool, as the characteristic aromatic component of O. fragrans, holds significant potential for applications in the flavor and fragrance industry. Although jasmonic acid (JA) is well documented to regulate the biosynthesis and accumulation of various plant secondary metabolites, its role in linalool biosynthesis remains largely unclear. Here, we discovered a positive correlation between the endogenous JA levels and linalool accumulation during the flowering stage of O. fragrans. Exogenous JA treatment was shown to enhance linalool biosynthesis by activating the linalool synthase gene OfTPS2. Dual-LUC and EMSA assays demonstrated that the key protein in the JA signaling pathway, OfJAZ3, interacted with OfMYB21 and subsequently suppressed the transcriptional activation of OfTPS2 mediated by OfMYB21. Functional validation further revealed that overexpression of OfJAZ3 significantly inhibited linalool biosynthesis in O. fragrans, A. thaliana, and N. tabacum plants. In contrast, JA promoted the degradation of OfJAZ3, thereby disrupting the formation of the OfJAZ3-OfMYB21 complex and relieving its inhibitory effect on OfTPS2. Split-LUC, BiFC, and pull-down assays confirmed that OfJAZ3 interacted with the F-box protein OfCOI1 (a key component of the E3 ubiquitin ligase SCFCOI1 complex), and JA treatment enhanced the strength of this interaction. Moreover, OfCOI1 was found to participate in OfTPS2 regulation by facilitating the ubiquitination and degradation of OfJAZ3. In conclusion, our findings elucidate the molecular mechanism by which OfJAZ3-OfMYB21 complex mediates JA signaling to regulate linalool biosynthesis in O. fragrans.

Synergistic defense in cotton: Lignin-mediated barriers and JA/ET signaling pathways against Verticillium wilt.

Functional characterization of the key enzyme gene SmAOC1/2 in Salvia miltiorrhiza Bunge jasmonic acid biosynthesis pathway.

Low-nitrate-inducible overexpression of PagTCP30.1 promotes root elongation in Populus alba × P. glandulosa (84 K).

MeJA regulates plant root growth, development and phosphorus uptake to adapt to low phosphorus stress.

Root-irrigation with Bacillus velezensis TX2 induces systemic resistance to soft rot disease via jasmonic acid and salicylic acid dependent pathways in Colocasia esculenta

Volatile organic compounds of Enterobacter asburiae SA-9 suppress Meloidogyne graminicola in Rice via multiple mechanisms.

CRISPR/Cas-mediated polyphenol oxidase gene knockout in potato reveals divergent roles in resistance to bacterial wilt and late blight.

Identification and validating native biocontrol bacteria Bacillus strain MZ3-12 against bacterial wilt.

Genomic and functional analysis of Pseudomonas protegens CS11 reveals multifaceted biocontrol mechanisms against Sclerotinia sclerotiorum via antifungal metabolites, root colonisation and plant defence induction in tomato.

Dynamic transcriptomic and metabolomic responses of rice under high light stress.

Multi-omics reveals that Sophora alopecuroides lysine decarboxylase (SaLDC)-mediated polyamine metabolism enhances salt tolerance and early flowering in Arabidopsis.

Deciphering serotonin's functional role in postharvest: Fruit-specific preservation of red fruit quality.