Phytohormones play essential roles in plant-nematode interactions through complex crosstalk. Although these hormones often accumulate in nematode-resistant plants, the roles of abscisic acid (ABA) and ethylene (ET) in rice (Oryza sativa) resistance to the root-knot nematode (RKN) Meloidogyne graminicola (Mg) remain unclear, particularly regarding concentration dependency and underlying mechanisms. Using exogenous hormone gradient treatments, we show that only high concentrations of ABA (200 µM) and ET (500 µM) induce systemic nematode resistance. High-concentration ET triggers endogenous systemic accumulation of ET and jasmonic acid (JA), accompanied by transient suppression followed by delayed accumulation of ABA, and induces JA-, ABA-, and salicylic acid (SA)-associated transcriptional responses. Exogenous ABA leads to endogenous ABA and SA accumulation and increased expression of related genes, while it suppresses ET biosynthesis gene expression and levels, highlighting a negative feedback effect of ABA on ET. Both hormones converge on a common mitogen-activated protein kinase 5 (OsMPK5)-dependent transcriptional and translational module. Low doses of ABA (50 µM) failed to activate this module and induced plant susceptibility, highlighting a threshold requirement for immune activation. Offspring of rice plants treated bi-weekly with high doses of ABA or ET were less susceptible to nematodes. This intergenerational acquired resistance was also OsMPK5-dependent. Our findings reveal concentration-dependent systemic effects of ABA and ET, whereby high-dose ABA and ET converge on OsMPK5 to reprogram translation and defense gene expression, underpinning both immediate and heritable resistance to root-knot nematodes.

Targeted disruption of a cell wall-modifying gene α-Mannosidase using CRISPR-Cas9 enhances post-harvest shelf life in tomato through ABA accumulation.

Naringenin as a bioactive preservative: Coordinated suppression of ethylene biosynthesis and cell wall disassembly delays apple senescence during storage

Sex determination underpins genesis of male and female flowers with particularly important implications in plant breeding. Auxin and ethylene regulate femaleness in cucurbits. In this work, we identified an auxin response factor 3 (CsARF3) that plays an essential role in carpel development in cucumber. Deletion of CsARF3 resulted in an androecious phenotype with only male flowers, whereas overexpression of CsARF3 led to an increased number of female flowers. CsARF3 promotes femaleness by directly stimulating the expression of the meristem maintenance gene CsSTM and repressing the activity of the gynoecious gene CsWIP1. Auxin and ethylene exhibit a reciprocal relationship during sex determination, in which ethylene promotes carpel formation through auxin at the early stage of flower development. The auxin signaling in carpels then enhances ethylene biosynthesis to inhibit stamen development.

Immune response of root-knot nematode-infected tomato is improved by biogenic copper nanoparticles.

PpERF.E3 regulates peach fruit ripening and softening by mediating ethylene biosynthesis and cell wall degradation

Control of fruit ripening, quality and yield is of major scientific, nutritional and commercial importance. The burst of ethylene (ET) production at the initiation of ripening is the most critical event controlling climacteric (CL) fruit ripening, yet little is known about how it is initiated. ABA is known to be capable of inducing ET production in many biological processes. However, the mechanism for this ABA induced ET production (AEP) and its potential importance in the burst of ET production that initiates ripening are unclear. Here, we report a branched signalling network involving ABA-activation of multiple SlSnRK2 (SNF1-related protein kinase 2) kinases, which, when overexpressed in tomato, stimulated ABA-induced ET production. Two key components, SlSnRK2.1 and SlSnRK2.4, phosphorylate an HD-Zip homeobox transcription factor, SlHB1, which transcriptionally activates ACC oxidase (SlACO1), required for ethylene synthesis. Concurrently, SlSnRK2.1 and SlSnRK2.4 phosphorylate two mitogen-activated protein kinases, SlMPK1/2, resulting in the post-translational stabilisation of ACC synthase (SlACS2), which generates the precursor 1-aminocyclopropane-1-carboxylic acid (ACC) that is converted to ET by ACO1. Removal of SlSnRK2.1 by CRISPR/Cas9 mutation was sufficient to alter the progress of fruit ripening. These results indicate that ABA is a primary hormonal signal modulating CL fruit ripening that stimulates ethylene production by targeting different steps in the ethylene biosynthesis pathway by both transcriptional and post-translational mechanisms. Further analysis revealed that removal of SlSnRK2.1 signalling also affected other aspects of the life cycle by prolonging the flowering period and suppressing seed development, indicating the potential for modifying fruit cropping and seedlessness.

ABSTRACT The developmental processes leading to the “ready to eat” ripening stage in kiwifruit differs by variety. In the present study, the effects of exogenous ethylene on quality and volatile compounds, as well as ripening-related gene expression, of red-fleshed kiwifruit cultivars (Actinidia chinensis cv. “Hongyang” and “Qihong”) were investigated. For postharvest ripening, uniform-sized fruits free from physical defects were treated with exogenous ethylene at 100 μL L−1 for 3 days at 25°C. At the “ready to eat” stage, soluble solids content was increased; however, firmness and titratable acidity decreased clearly in both cultivars. A total of 28 volatile compounds were identified including, 10 aldehydes & amines, 7 alcohols, and 11 esters. The ethanol and methyl butanoate showed strong associations with the ethylene treatment in both cultivars. In addition, results indicated that the “ready to eat” stage in red-fleshed kiwifruit could be distinguished by hexanal in “Hongyang,” and by both hexanal and (E)-2-hexenal in “Qihong.” Transcriptome analysis identified 121 and 1813 unigenes that were differentially expressed in the control 3-day and ethylene 3-day treatments vs. at harvest, respectively, in “Hongyang.” In “Qihong,” a total of 45 and 1136 unigenes were differentially expressed in the same comparison. Among these, genes involved in ethylene biosynthesis, cell wall degradation, and volatile emission, such as ACO, β-gal, PL, and Alcohol dehydrogenase, were significantly upregulated by ethylene treatment, which contributes to “ready to eat” quality of both kiwifruit cultivars.

CsNAC25 negatively regulates cold tolerance in tea plants through modulation of CBF pathway and ethylene biosynthesis.

Cadmium-induced ER stress, autophagy and ethylene biosynthesis in leaves and roots of Arabidopsis thaliana and their dependence on stress intensity

Ethylene promotes lateral root formation following waterlogging in an epiphytic orchid, Cymbidium tracyanum.

Metabolic network divergence: polyamine and ethylene biosynthesis dynamics in Arabidopsis thaliana and Solanum lycopersicum

SUMMARYFar‐red (FR) light, a critical environmental signal perceived via phytochrome photoreceptors, modulates numerous aspects of plant development; yet, its role in reproductive processes such as fruit growth and ripening remains less clear. In this study, we investigated the developmental stage‐specific effects of FR light on fruit development, anatomy, and metabolism in dwarf tomato (Solanum lycopersicum) plants. FR light was applied during three distinct stages: vegetative phase, early fruit development, and late fruit development. Three corresponding plant batches were analyzed: (i) full‐growth cycle plants for final fruit weight and plant architecture, (ii) plants harvested at the mature green stage for anatomical measurements, and (iii) plants during early fruit formation for integrated transcriptomic and metabolomic profiling of source (leaf) and sink (fruit) tissues. FR exposure from flowering to the full‐grown green fruit stage increased total fruit weight by enhancing fruit size, linked to an increase in both mesocarp cell layers and cell size. These anatomical changes were associated with transcriptional upregulation of genes related to auxin, gibberellins, and brassinosteroid biosynthesis and signaling in both leaves and fruits. Additionally, FR light accelerated the onset of ripening, coinciding with transcriptional upregulation of abscisic acid and ethylene biosynthesis pathways. Furthermore, our results reveal that FR light is initially perceived in leaves and subsequently modulates fruit development and ripening through hormone‐mediated signaling. This study provides new insights into the light‐regulated plasticity of reproductive development and highlights the importance of FR timing in optimizing fruit fresh weight and sugar content.

Endogenous ethylene production occurs across biological kingdoms, yet its pathophysiological roles remain incompletely defined. In situ detection of ethylene is impeded by its inherent volatility and chemical inertness. Here, we report BORh, a new turn-on fluorescent probe that operates via ethylene-triggered displacement of a rhodium quencher from a BODIPY-rhodacycle scaffold, liberating the intensely fluorescent BOET. BORh exhibits high sensitivity and selectivity, broad pH tolerance, and negligible cytotoxicity. In mammalian PC12 cells, it permits real-time visualization of both exogenously supplied and in situ generated ethylene. Within photosynthetic systems, BORh overcomes cell wall barriers and chlorophyll autofluorescence, enabling in situ monitoring of ethylene dynamics in algae (Chlamydomonas reinhardtii) and higher plant (Arabidopsis thaliana and Allium cepa) tissues. Remarkably, BORh-enabled fluorescence imaging revealed synchronous upregulation of ethylene and reactive oxygen species (ROS) under plant abiotic stress. H2O2 exhibited concentration-dependent biphasic regulation of ethylene biosynthesis, whereas ethylene exerted no reciprocal effect on ROS generation. These findings establish ROS as upstream regulators of ethylene biosynthesis within plant stress signaling cascades. BORh emerges as a robust chemical tool for spatiotemporal dissection of ethylene biochemistry, offering new insights into ROS-ethylene crosstalk during plant stress responses and paving the way for future investigations of ethylene function in mammalian pathophysiology.

Waterlogging stress is a major abiotic stress that severely limits plant growth and development. However, little is known about the effects of waterlogging stress on the growth and development of gymnosperms. In this study, we demonstrated that the TgRAV1-TgWRKY74-TgACS13 module regulates ethylene-enhanced root vitality during waterlogging stress in the gymnosperm Torreya grandis. Root vitality, the physiological status of root tissues, reflects their metabolic activity and cell viability of roots. Waterlogging stress induces ethylene accumulation in T. grandis roots, thereby enhancing root vitality. The ethylene biosynthesis gene TgACS13 positively regulates root vitality under waterlogging stress by increasing ethylene levels. The transcription factors TgWRKY74 and TgRAV1 directly regulate TgACS13 expression by binding to its promoter. Furthermore, waterlogging stress activates TgWRKY74 to promote TgACS13 transcription and alleviates the inhibitory effect of TgRAV1 on its expression, resulting in ethylene-enhanced root vitality during waterlogging stress. In addition, TgRAV1 interacts with TgWRKY74 both in vivo and in vitro, reducing the transcriptional activity of TgWRKY74 by inhibiting its DNA-binding ability without affecting the transcriptional activity of TgRAV1. Therefore, the TgRAV1-TgWRKY74 module finely tunes TgACS13 expression to regulate ethylene accumulation through multiple mechanisms, thereby maintaining the vitality of T. grandis roots exposed to waterlogging stress.

Timely initiation of fruit ripening is crucial for improving agricultural efficiency and shelf life. While the progression of tomato ripening and the roles of ethylene and its core transcriptional controls are well established from the breaker (BR) stage onwards, the molecular mechanisms that fine-tune the transition from fruit development to ripening remain poorly understood. In this study, we identified a previously uncharacterized NAC transcription factor (TF), Ripening Accelerator (RAR), as a key negative modulator of climacteric ripening onset. In fruit, RAR is highly expressed at the mature green (MG) stage and downregulated at BR stage, preceding the climacteric ethylene burst. Silencing RAR via RNA interference significantly accelerated fruit ripening and ethylene production prior to BR stage, especially under high light conditions. RAR directly represses ACC Synthase 2 (ACS2), a key ethylene biosynthesis gene. Although RAR can form a heterodimer with the ripening-promoting NAC TF Non-Ripening (NOR), this heterodimer exhibits weaker transcriptional activation than the NOR homodimer, indicating a repressive effect of RAR on NOR-mediated activation. Moreover, RAR expression is negatively regulated by ethylene, forming a feedback loop that modulates the timing of ripening onset. Our findings uncover a previously unrecognized regulatory checkpoint in the ripening program, where RAR probably acts as a developmental safeguard to prevent premature ripening. Targeted manipulation of RAR offers a promising strategy for fine-tuning ripening onset and improve postharvest fruit quality across diverse environmental conditions.

Ethylene is a key hormone in plant development, but how its endogenous levels quantitatively regulate the dose-dependent balance between cotton fiber length and strength has been poorly understood. Here, it is shown that natural variations in ethylene content across Gossypium species (G. hirsutum, G. arboreum, and G. raimondii) correlate with their distinct fiber length and secondary cell wall (SCW) attributes. A post-translational mechanism is identified where a kinase-deficient variant of CASEIN KINASE1 (PK1) stabilizes key ACS1 isoforms to enhance ethylene biosynthesis. In tetraploid cotton (G. hirsutum), elevated ethylene inhibits elongation but promotes SCW deposition, yielding shorter, stronger fibers, while suppressing GhACS1 impairs both processes. Mechanistically, a hierarchical GhEIN3-GhERF-GhCOBL4 transcriptional cascade is uncovered that orchestrates this balance. Remarkably, elevating ethylene in the diploid ancestor G. arboreum elicits the opposite phenotype: longer, thinner fibers. This is explained by a functional inversion in the transcriptional response of the physically conserved cascade, which is activated in G. hirsutum but repressed in G. arboreum. The findings establish a tunable module governing a dose-dependent balance between fiber length and strength, and its evolutionary divergence provides novel targets to break this developmental constraint in cotton engineering.

Abstract The plant hormone salicylic acid (SA) effectively suppresses ethylene biosynthesis in apple (Malus domestica) fruit. However, the underlying molecular mechanism remains unclear. Here, we identified a WRKY transcription factor, MdWRKY40, which was upregulated in response to SA treatment. MdWRKY40 functioned as a transcriptional repressor of the ethylene biosynthesis gene MdACS1 (1-aminocyclopropane-1-carboxylic acid synthase 1). In addition, we found that the expression of U-box-type E3 ubiquitin ligase MdPUB24 was downregulated following SA treatment. MdPUB24 interacted with MdWRKY40 and mediated its ubiquitination, leading to the degradation of MdWRKY40 via the 26S proteasome pathway, which was suppressed by SA. Together, these results suggest that the MdPUB24-MdWRKY40-MdACS1 regulatory module mediates SA-induced suppression of ethylene biosynthesis by post-translational modification during apple fruit ripening. These findings offer new insights into the molecular basis of fruit ripening inhibition and shelf-life extension.

Lateral root (LR) formation is governed by a complex regulatory network that includes various internal factors such as transcription factors (TFs) and phytohormones, of which ethylene is a key repressor. However, the core TFs that regulate ethylene biosynthesis and LR development remain unknown. Here, we found that the WRKY TF SbWRKY50 was required for LR development in Sorghum bicolour L. Overexpression of SbWRKY50 in sorghum increased the number and length of LRs, whereas both decreased in the CRISPR/Cas9-edited SbWRKY50 mutant. SbWRKY50 positively regulated LR generation by directly repressing several 1-aminocyclopropane-1-carboxylate synthase (ACS) genes. In addition, SbWRKY50 directly interacted with SbBMI1A to facilitate the recruitment of the PRC1 complex and induced H2A ubiquitination (H2Aub) accumulation on SbACS genes, thereby promoting epigenetic silencing and LR formation. The positive role of SbWRKY50 in stay-green and LR formation improves the agronomic traits of sorghum, improving drought tolerance and potentially contributing to increased sorghum yield.

In plants, ABF (ABA-responsive element binding factor)/AREB (ABA-responsive element binding) proteins regulate processes such as abiotic stress response, pathogen defense, and seed germination. However, the specific function and regulatory networks of ABF/AREB transcription factors during fruit ripening remain largely unknown. In this study, we found that the expression level of SlABF4 is abundant in tomato fruits and gradually decreases during the ripening process. Functional analysis confirmed that SlABF4 was localized in the cell nucleus and responded to ABA treatment. To further investigate the function of SlABF4 in fruit ripening, we generated overexpressing SlABF4 lines and CRISPR/Cas9-slabf4 knockout mutants. Compared with wild type (WT), the onset of fruit ripening in OE-SlABF4 lines was delayed and ethylene production reduced, while the slabf4-deficient mutants showed accelerated fruit ripening and increased ethylene release. Meanwhile, transcriptomic and qRT-PCR analyses indicated that the expression levels of several fruit ripening-related transcriptional factors and ethylene-associated genes were downregulated in OE-SlABF4 lines and upregulated in CR-slabf4 mutants. Importantly, yeast one-hybrid (Y1H), dual-luciferase reporter assays and electrophoretic mobility shift assays (EMSA) demonstrated that SlABF4 directly binds to the promoters of ethylene biosynthesis genes (SlACS2 and SlACS12) and represses their expression. Moreover, we found that SlABF4 can physically interact with two key ripening-related transcription factors (SlFUL1 and SlMADS1) to regulate tomato fruit ripening in vivo and in vitro, while SlABF4 inhibited the expression of SlACS2 to modulate ethylene biosynthesis. Together, these findings expand our insights into the negative regulatory role and molecular mechanism of SlABF4 in the fruit ripening process, which will provide support for precise breeding designed to mediate fruit ripening in tomato.