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Phytochrome-interacting factor 1b (SlPIF1b) affects the fruit quality of tomato by regulating chloroplast development.

The increased abundance and functionality of fruit chloroplasts could promote the accumulation of nutrients and flavor in the fruit. Tomato fruit has fully developed fruit chloroplasts, whose abundance and functionality have much untapped potential in improving fruit quality by controlling fruit chloroplast development. Previous studies have identified many regulatory factors that specifically regulate fruit chloroplast development in tomatoes, but there are fewer reports on tomato phytochrome-interacting factors (SlPIFs). Arabidopsis AtPIFs have been implicated in chloroplast development and chlorophyll biosynthesis. In this study, we identified and characterized an SlPIF1b mutant in tomato, named GS, which exhibited a dark green fruit shoulder with enhanced chloroplast development. RNA-seq and genotyping analysis identified a - 21 bp (A → T) mutation in the promoter of SlPIF1b, resulting in the absence of the TATA-box core transcriptional element and inhibiting SlPIF1b transcription. The overexpression of SlPIF1b in GS inhibited chloroplast development of fruits, leading to a lighter green shoulder color, decreased chlorophyll content, reduced photosynthetic activity, diminished starch accumulation, and compromised fruit quality upon ripening. Conversely, the down expression of SlPIF1b significantly enhanced fruit chloroplast development and functionality in fruits, resulting in increased chlorophyll and carotenoid accumulation. Further analysis of expression profile and transcriptional activity indicated that SlPIF1b could bind to G/PBE-box elements present in SlGLK2, SlTKN4, SlCAO1a, SlPOR1, SlPOR3, SlCAB1 and SlCAB1b promoters, thereby inhibiting their expression. This study revealed the specific regulatory mechanism by which SlPIF1b modulates chloroplast development and chlorophyll synthesis in tomato fruit and provided valuable genetic resources and a theoretical basis for tomato quality improvement.

Solanum lycopersicum

Slmsh1-induced heritable enhancement of traits for tomato breeding improvement.

Vegetable grafting is a horticultural technique employed to develop specialized plant varieties by effectively enhancing resistance to both biotic and abiotic stresses, as well as improving fruit quality and yield. However, these advantageous traits are generally non-heritable. The MSH1 gene induced heritable enhancement-through-grafting (HEG) effect on growth vigor, demonstrating promising application potential. In this study, we employed the msh1 mutant tomato as a rootstock to induce heritable superior traits and combined this approach with hybridization techniques to enhance tomato cultivars. Three Slmsh1 mutants were generated using CRISPR/Cas9 which exhibited a dwarf phenotype with whitened spots. By grafting several distinct inbred lines onto Slmsh1, we observed significant HEG, drought stress tolerance, and fruit quality. Under drought conditions, Slmsh1-grafted tomato seedlings exhibited increased biomass and enhanced drought tolerance through the regulation of antioxidant enzyme activities. Differential expression and methylation analyses of the graft progeny revealed that these heritable enhanced traits (HETs) are likely attributable to epigenetic modifications in the expression of ROS-scavenging- and hormone-related genes. Furthermore, to explore practical applications, we crossed inbred lines with HETs and evaluated the growth, yield, and fruit quality of the resulting hybrid combinations. The results indicated that these hybrid combinations improved fruit yield and quality, enhancing the total soluble solids, soluble sugar, and soluble protein content. These findings suggest that Slmsh1-grafted progenies enhanced plant biomass and drought resistance, while their hybrid combinations positively influenced root growth, yield, and fruit quality, providing new insights into the synergistic integration of genome editing and conventional breeding.

Solanum lycopersicum

Alternative oxidase pathway inhibits PuWRKY7-PuHDAC15 complex to promote ester aroma synthesis in Nanguo pear.

Volatile esters are key contributors to the characteristic aroma in fruit, and their accumulation directly dictates fruit quality and consumer acceptance. The alternative oxidase pathway is known for its role in regulating fruit quality, but its molecular mechanism in ester aroma accumulation remains unclear. Here, we demonstrated that the alternative oxidase pathway acts as the dominant respiratory pathway in Nanguo pear (Pyrus ussuriensis) during ripening and promotes ester aroma accumulation by increasing histone acetylation levels of PuAAT1 (alcohol acetyltransferase 1), the key gene governing ester synthesis. Further, we identified PuHDAC15 as a critical histone deacetylase that modulates acetylation levels and interacts with the transcription factor PuWRKY7. Mechanistically, PuWRKY7 directly binds to the W-box elements in the PuAAT1 promoter. The PuHDAC15-PuWRKY7 complex acts synergistically to repress PuAAT1 transcription, thereby decreasing its histone acetylation levels and gene expression, and consequently inhibiting ester aroma accumulation in Nanguo pear. This study reveals how the alternative oxidase pathway integrates into fruit aroma formation via epigenetic regulation and gene expression, thereby providing a scientific basis for targeted improvement of fruit quality.

Plant Proteins

Molecular mechanisms and agronomic strategies for thermotolerance in chili pepper (Capsicum annuum L.).

Heat stress is a primary environmental constraint on chili pepper (Capsicum annuum L.) productivity and fruit quality across global agricultural systems. Elevated temperatures adversely affect plant growth, flowering, fruit set, pod morphology, physiology, and metabolism. The severity of these impacts varies with the duration and intensity of heat exposure and with the stage of plant development. Reproductive development is especially vulnerable, resulting in compromised fruit formation and a decline in productivity. Heat stress disturbs photosynthesis, cellular structure integrity, and membrane stability through oxidative stress. Chili plants counter heat stress through complex molecular networks that encompass activation of antioxidant systems, heat shock protein (HSP) synthesis, osmolyte biosynthesis, and stress-responsive transcription factor expression. Recent advancements in genomics, transcriptomics, and metabolomics have elucidated fundamental regulatory pathways governing thermotolerance, highlighting the importance of heat-responsive genes, including CaHSPs, CaWRKYs, and CaNACs. This comprehensive review integrates contemporary understanding of physiological, biochemical, and molecular heat stress responses in chili pepper. Additionally, it evaluates potential agronomic and breeding strategies to strengthen crop adaptation to escalating global temperatures.

Capsicum

Cucurbitacins in Plant-Insect Interactions: Biosynthesis, Regulation, Ecological Functions, and Prospects for Crop Protection.

Cucurbitacins are highly oxygenated tetracyclic triterpenoids characterized by intense bitterness, substantial structural diversity, and important consequences for plant-herbivore interactions. Although best known from Cucurbitaceae, cucurbitacins and related cucurbitane-type metabolites also occur in phylogenetically distant herbaceous and woody plants. Genetic and biochemical studies have validated several core biosynthetic steps, including cucurbitadienol formation by oxidosqualene cyclases and subsequent modification by cytochrome P450 monooxygenases, acyltransferases, and glycosyltransferases. Tissue-preferential basic helix-loop-helix transcription factors constitute the best-characterized regulatory layer, whereas the evidence supporting accessory regulators, transporters, and environmental responses varies from functional validation to transcriptomic or genomic prediction. From the plant perspective, cucurbitacins deter feeding or impair performance in many generalist and non-adapted herbivores. By contrast, their use as host-recognition cues and feeding stimulants by specialist diabroticite beetles reflects evolved herbivore adaptations involving perception, tolerance, metabolism, or sequestration rather than a second defensive function of the plant trait. Herbivore-induced cucurbitacin accumulation has been demonstrated in particular systems, although its regulatory mechanisms and ecological generality remain unresolved. Unlike previous reviews centered primarily on cucurbitacin chemistry, pharmacological activity, or individual biosynthetic pathways, this review integrates evidence-graded pathway reconstruction and molecular regulation with taxonomic distribution, insect adaptation, domestication, and agroecological consequences. Mechanistically, this review traces how scaffold formation, oxidative tailoring, conjugation, tissue-specific regulation, and transport give rise to contrasting ecological outcomes through herbivore-specific perception, tolerance, metabolism, and sequestration. We conclude that uniformly increasing or eliminating cucurbitacins is unlikely to provide broadly effective crop resistance because either direction may favor a different herbivore group. Future priorities include functional validation of candidate genes, spatially resolved metabolite analysis, comparative investigation of non-cucurbit lineages, and field evaluation involving generalist and specialist herbivores, crop quality, and non-target organisms. These advances will support context-specific fruit-quality improvement, behavioral pest control, and integrated pest management strategies rather than cucurbitacin manipulation as a stand-alone resistance approach.

agroecology

Cis-regulatory variation in the MdCKX6 promoter is associated with allele-specific expression and fruit size in apple.

Fruit size is a key determinant of apple fruit quality and market value and is strongly influenced by phytohormone-regulated cell proliferation and expansion during early fruit development. Cytokinin oxidase/dehydrogenase (CKX) enzymes regulate cytokinin homeostasis by irreversibly degrading active cytokinins, but the contribution of natural variation in CKX genes to fruit size remains poorly understood. Here, we identified MdCKX6 as a candidate regulator of fruit growth in apple (Malus domestica). MdCKX6 exhibited pronounced allele-specific expression during fruit development in the cultivar 'Royal Gala'. Sequence analysis identified a promoter SNP associated with differential promoter activity and allele-specific expression. Genotyping of diverse apple cultivars and wild Malus accessions revealed a significant association between MdCKX6 promoter genotype and fruit size. Cultivars carrying low-expression alleles produced larger fruits, whereas high-expression alleles were associated with smaller fruits. To investigate gene function, MdCKX6 was overexpressed in tomato, resulting in reduced fruit size. Histological analyses of the transgenic tomato fruit revealed smaller pericarp cells. Transcriptome analysis of transgenic fruits revealed widespread changes in genes associated with cell-cycle regulation, cell wall modification, hormone-related processes, and transcriptional regulation. Together, these results identify MdCKX6 as a potential negative regulator of apple fruit growth and reveal an association between cis-regulatory variants, gene expression, and fruit size. This study provides new insights into the role of cytokinin metabolism in fruit development and highlights regulatory variation in MdCKX6 as a potential target for apple breeding.

Malus

Genome Editing in Solanaceae: Harnessing CRISPR-Cas Technology for Precision Crop Improvement.

Malnutrition and climate-induced stress remain major constraints to global food and nutritional security despite the yield gains of the Green Revolution. Solanaceae crops such as tomato, potato, brinjal, and pepper are key sources of vitamins, minerals, and bioactive compounds. Yet, their genetic improvement has been limited by narrow diversity and complex polygenic traits. The advent of CRISPR/Cas-mediated genome editing provides a transformative platform for precision crop improvement by enabling targeted modification of genes controlling stress tolerance, yield, and nutritional quality. In Solanaceae, CRISPR/Cas applications have successfully enhanced resistance against major pathogens (SlMlo1, SlPelo, SlDCL2), improved abiotic stress tolerance through editing of SlMAPK3, SlCBF1, and SlBZR1, and optimized fruit quality traits via modulation of Psy1, CrtR-b2, and fiAD2/3. Emerging innovations, such as base and prime editing, and RNP-mediated transgene-free delivery, are expanding the precision and scope of editing. However, challenges persist, including genotype-dependent transformation, low HDR efficiency, and incomplete understanding of off-target and epigenetic effects. Integrating CRISPR with omics-guided gene discovery, efficient transformation systems, and regulatory harmonization can accelerate the development of nutritionally enriched, stress-resilient, and sustainable Solanaceae varieties. This review synthesizes recent advances, identifies critical limitations, and outlines future opportunities for deploying CRISPR/Cas technology to achieve next-generation breeding and food system resilience.

CRISPR/Cas

The TANG cluster comprising ten nitrate transporter genes controls fruit sweetness and size in tomato.

Sucrose is a major transport form of photoassimilated carbon in tomato, Arabidopsis, and many other plant species, and plays a critical regulatory role in plant growth, development, and fruit quality. Plant vacuoles function as storage organelles, accumulating substantial quantities of metabolically inactive nitrates as a nitrogen reserve and soluble sugars as a carbon reserve. Consequently, the balance between nitrate and sucrose accumulation determines plant growth dynamics and fruit taste. In this study, we identified a gene cluster designated TANG (Total soluble solidsAccumulation viaNitrate transporterGene cluster), comprising ten nitrate transporter genes that are significantly associated with sucrose accumulation in tomato. This gene cluster mediates the transport of nitrate between the cytoplasm and vacuole, thereby influencing its storage. Functional disruption of TANG8, a member of the gene cluster, results in either enhanced sugar accumulation or increased fruit size. Selective disruption of multiple TANG cluster members yields fruits with elevated sweetness and increased fruit size in S. pimpinellifolium. The interaction between the TANG members and a tonoplast localized Sucrose Transporter 4 provides insight into the competitive accumulation of nitrate and sugar. The multiplex editing of a gene cluster provides a successful example of engineering crops with high quality and yield.

Gene cluster

High temperature induces MdGATA15 to suppress anthocyanin accumulation in apple peels.

Although GATA transcription factors are known to play broad roles in plant growth, development, and stress responses, their involvement in high-temperature-induced anthocyanin suppression remains largely unexplored. In this study, using "Otome" as the experimental material, we revealed the important role of MdGATA15 in inhibiting anthocyanin accumulation under high temperature through multiple molecular mechanisms. A series of physiological and biochemical experiments demonstrated that MdGATA15 directly binds to the promoters of anthocyanin activators MdMYB11, MdANS, and the transporter gene MdGSTF12, repressing their expression. Simultaneously, MdGATA15 activates the expression of the anthocyanin biosynthesis repressor MdMYB308, further enhancing the inhibition. Notably, MdGATA15 binds to its own promoter, forming a positive feedback loop that significantly enhances its expression under high-temperature conditions. This mechanism provides new insights into understanding how apple responds to high-temperature stress. Additionally, we identified the bHLH transcription factor MdPIF4-Like3 in apple as an interactor of MdGATA15, which stabilizes and enhances the transcriptional activity of MdGATA15, thereby further reinforcing the inhibition of anthocyanin biosynthesis. These findings highlight the central role of MdGATA15 in high-temperature-mediated suppression of anthocyanin synthesis in apple and provide significant advances in understanding the molecular mechanisms of apple's response to heat stress. This study provides a theoretical basis for breeding heat-resistant apple cultivars with improved fruit quality by targeting key transcription factors involved in high-temperature stress response.

Anthocyanins

Genomics control of biostimulant-induced stress tolerance and crop yield enhancement.

Biostimulants are changing modern agriculture, as they have the potential to secure healthy and sustainable food production while preserving the environment. They have two main biological effects: growth promotion and stress protection. Both effects can lead to enhancement of the yield and improvement of the marketable grade of the produce in crops, without compromising crop quality. Their use increased exponentially in the past decade, as they are highly efficient, ecologically friendly (non-toxic, biodegradable), and applicable to all major crops. While exponential data on the physiological mechanisms of stress protection is accumulating in recent years, the information as to how biostimulants act at the molecular level is still rather limited. Here we review the growing evidence of the biostimulants role in stress protection and yield enhancement of crops, as well as the recent transcriptomic and metabolomic data, which indicate biostimulants' molecular mode of action. In particular, we outline the role of genes encoding signaling components, plant hormones (abscisic acid, brassinosteroids, and ethylene), genes encoding transcription factors from ERF, WRKY, NAC, and MYB families, and genes related to growth, photosynthesis, and stress response. Finally, we describe strategies to study the genetic and genomics control of biostimulants mode of action, with foci on stress tolerance and yield enhancement. In Arabidopsis, established systems for biostimulants-induced protection against drought and oxidative stress will allow both forward and reverse genetics approaches to identify key genes from the biostimulants network. Mutations in such genes compromise the stress-protective effect of biostimulants. In major crops such as pepper and tomato, large Genome Wide Association Studies (GWAS) panels can be utilized to study crops responses to biostimulants in terms of drought tolerance, fruit qualities, and yield in order to pinpoint genes controlling biostimulants-induced stress protection and yield enhancement. The combination of these approaches allows identification and verification of important genes involved in the pathways of biostimulant-induced stress protection and yield enhancement, as well as deciphering parts of the intricate biostimulant-signaling network.

Crops, Agricultural

Engineering cold stress resilience in capsicum annuum through functional genomics and precision breeding.

This review synthesizes the molecular mechanisms of cold tolerance in pepper, integrating multi-omics data,genome editing, and precision breeding strategies to accelerate the development of cold-resilient cultivars. Cold stress is a significant environmental factor that affects the growth, productivity, and fruit quality of Capsicum annuum by impairing membrane integrity photosynthesis and cellular redox homeostasis. Although pepper has several endogenous cold-responsive regulators such as CaNAC035 and CabHLH035, along with antioxidant defense systems, its cold tolerance remains limited due to low transcriptional activation of key regulators, functional redundancy among cold-responsive genes, and the polygenicity of cold tolerance. These complexities, combined with low genetic diversity and linkage drag, have hindered the improvement of cold-resistant cultivars through conventional breeding. This review brings together the recent progress in understanding the molecular mechanisms of cold stress perception, signal transduction, transcriptional regulation, metabolic reprogramming, and phytohormone interactions in pepper. Precision Breeding 2.0 is a new innovation that combines the integration of multi-omics-based target identification with next-generation genome-editing techniques, allowing precise and multiplex engineering of complex and interconnected regulatory networks instead of single genes. We cover new approaches such as engineering the DREB/CBF pathway, allele-specific editing and targeted disruption of negative regulators to enhance the pathway(s) involved in cold response. Moreover, we propose a roadmap for integration of transcriptomics, proteomics, metabolomics, high-throughput phenomics, and speed breeding to accelerate the identification, validation, and deployment of superior alleles to boost cold tolerance. This review provides a foundation for developing climate-resilient pepper cultivars by connecting functional genomics with precision genome engineering approaches to maintain productivity under variable environmental conditions.

Capsicum

Genome-wide identification of potassium transporters and channels in Malus domestica genome.

Potassium (K+) is an essential nutrient for plants. It contributes to most physiological and biochemical pathways for plant metabolism, growth, and development. It is the most available plant nutrient, comprising 10–15% of plant weight. Plants have a sophisticated system of K+ transporters and channels for distribution in plant body. Apple is one of the most consumed fruits in the world. Its fruit quality and yield are positively affected by K+. However, limited information is available about K+ transport systems in Apple. In this study, 47 candidate genes (26 K+ transporters and 21 K+ channels) have been identified in Apple (Malus domestica) genome. The phylogenetic comparisons with other plants (Glycine max, Arabidopsis thaliana, and Oryza sativa) indicated that the K+ transport system is much conserved among different plants. The analysis of Gene structure showed the presence of specific introns and exon patterns for these gene families. Transcriptomic data analysis and RT-qPCR demonstrated significant variations in the transcript abundance of these genes in response to abiotic stresses. The current project represents the first report about the K+ transport system in Apple. Therefore, it may act as a starting point for further functional characterizations.

Malus

The genetic basis of chloride exclusion in grapevines.

Mediterranean regions are among the most important areas for global grape production, characterized by dry climates and frequent challenges associated with soil salinity. In these environments, chloride toxicity is a major factor limiting vine growth and fruit quality. Despite the critical role of chloride exclusion in salinity tolerance, the genetic mechanisms underlying this trait remain poorly understood. In this study, we analyzed natural variation in chloride exclusion using a diverse panel of 335 accessions representing 18 wild and cultivated Vitis species. This panel, comprising accessions from the southwestern United States and Mexico, captures a broad range of evolutionary adaptations to abiotic stress and provides a valuable genetic resource for breeding efforts aimed at introducing novel traits. Using genome-wide association and quantitative trait loci (QTL) mapping, we identified a major QTL on chromosome 8, now designated qClEx8.1, containing candidate genes encoding cation/H⁺ exchangers (CHXs), which are involved in ion transport and homeostasis. To validate these findings, we analyzed a mapping population derived from Vitis acerifolia longii 9018 and the commercial rootstock GRN3, confirming the chromosome 8 locus as a major determinant of chloride exclusion. Structural variant analysis revealed nonsynonymous substitutions within CHX genes that may influence protein function and salinity tolerance. Additionally, we discovered a novel QTL on chromosome 19 enriched with G-type lectin S-receptor-like serine/threonine-protein kinases, known regulators of stress signaling. By integrating phenotypic and genomic data across a diverse Vitis collection, this study advances our understanding of the genetic architecture underlying chloride exclusion and highlights candidate genes for breeding salt-tolerant rootstocks.

Vitis

GA4+7 alleviates pear fruit semi-russeting partly by suppressing PRX-mediated lignin deposition.

Pear fruit semi-russeting is a surface disorder that frequently occurs during fruit development and significantly diminishes fruit appearance quality and commercial value. Although Gibberellin 4 + 7 (GA4+7) has been used to reduce fruit surface defects in horticultural crops, the physiological and molecular mechanisms underlying its inhibitory effect on pear fruit semi-russeting remain poorly understood. In this study, preharvest GA4+7 treatment of 'Cuiguan' pear significantly reduced russet coverage and lignin accumulation in mature fruit skin without adversely affecting fruit size, fruit shape index, or total soluble solids content. Integrated metabolomic and transcriptomic analyses revealed that GA4+7 treatment was associated with the repression of phenylpropanoid and lignin biosynthesis at both metabolic and transcriptional levels. Among the lignin-related differentially expressed genes, two class III peroxidase genes, PpyPRX22 and PpyPRX65, were strongly downregulated by both GA4+7 and bagging treatments. Both proteins localized to the cell wall, and transient expression assays in pear fruit skin supported positive roles for PpyPRX22 and PpyPRX65 in lignin deposition. Furthermore, dual-luciferase reporter assays combined with transient overexpression experiments suggested that several PpyMYB transcription factors may regulate PpyPRX expression and lignin accumulation, with PpyMYB138 and PpyMYB139 significantly activating PpyPRX22 and/or PpyPRX65 promoter activity. Taken together, these results suggest that GA4+7 alleviates pear fruit semi-russeting at least partly by reducing lignin deposition in the fruit skin, with PpyPRX22 and PpyPRX65 potentially contributing to this process.

Class III peroxidase

Transcriptional landscape and dynamics involved in sugar and acid accumulation during apple fruit development.

In fleshy fruit, sugars and acids are central components of fruit flavor and quality. To date, the mechanisms underlying transcriptional regulation of sugar and acid during fruit development remain largely unknown. Here, we combined ATAC-seq with RNA-seq to investigate the genome-wide chromatin accessibility and to identify putative transcription factors related to sugar and acid accumulation during apple (Malus domestica) fruit development. By integrating the differentially accessible regions and differentially expressed genes, we generated a global data set of promoter-accessibility and expression-increased genes. Using this strategy, we constructed a transcriptional regulatory network enabling screening for key transcription factors and target genes involved in sugar and acid accumulation. Among these transcription factors, 5 fruit-specific DNA binding with one finger genes were selected to confirm their regulatory effects, and our results showed that they could affect sugar or acid concentration by regulating the expression of sugar or acid metabolism-related genes in apple fruits. Our transcriptional regulatory network provides a suitable platform to identify candidate genes that control sugar and acid accumulation. Meanwhile, our data set will aid in analyzing other characteristics of apple fruit that have not been illuminated previously. Overall, these findings support a better understanding of the regulatory dynamics during apple fruit development and lay a foundation for quality improvement of apple.

Malus

Integrated phytochemical and bioactivity profiling of Xanthium strumarium fruits from Korea and China: Implications for origin-specific quality specification.

BACKGROUND: Geographic origin influences the phytochemical composition and biological activities of medicinal plant resources. Xanthium strumarium L. (XS) fruit is widely used in East Asian traditional medicine. However, current pharmacopeial standards primarily recognize Chinese-derived material, despite the availability and traditional use of XS in Korea. To address this gap and support origin-informed quality specification, we compared fruits from Korea (XS-K) and China (XS-C) using chloroplast genome sequencing, targeted phytochemical profiling (high-performance liquid chromatography (HPLC) for selected phenolics and gas chromatography-flame ionization detection (GC-FID) for fatty acids and phytosterols, and multivariate chemometric analysis. RESULTS: Chloroplast genome analysis revealed high overall similarity but localized divergence around the rpoC2 locus and a greater mutation burden in XS-C, supporting origin-associated genomic differentiation. Phytochemical profiling revealed distinct origin-dependent metabolic signatures. XS-K showed higher levels of phytosterols, chlorogenic acid, 4,5-dicaffeoylquinic acid (4,5-DCQ), and xanthatin was detected only in XS-K, whereas XS-C exhibited greater abundance of total fatty acids, particularly oleic acid. Unsupervised clustering and log2 fold-change ranking confirmed clear compositional separation, and variable importance in projection (VIP) analysis identified chlorogenic acid, β-sitosterol, oleic acid, 4,5-DCQ, and xanthatin as major discriminators between origins. Bioactivity assays demonstrated that XS-K exerted stronger antioxidant effects in ABTS, DPPH and FRAP assays, stronger skin-related enzyme inhibition, and greater antibacterial activity against Staphylococcus aureus, consistent with its enriched phenolic and sterol profile. CONCLUSION: Together, chloroplast sequence variation, targeted metabolite quantification, and screening bioassays consistently distinguished XS-K from XS-C. These findings support the use of candidate markers for the origin-based authentication and quality control of XS fruit-derived ingredients. © 2026 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Fruit

Abscisic acid promotes RBOH-dependent reactive oxygen species production and lignin biosynthesis in pears via the PuABI5-PuMYB169 module.

Pear stone cell lignification, a critical determinant of fruit texture and quality, is regulated by developmental and environmental cues, with abscisic acid (ABA) playing a central role. However, the molecular mechanisms underlying its role in reactive oxygen species (ROS)-mediated lignification remain unclear. Here, we show that PuABI5, a key component in ABA signaling, directly combines with PuMYB169, the master regulator of stone cell lignification, to modulate ROS production and lignin biosynthesis in pear fruit. Exogenous application of ABA enhances H2O2 and lignin accumulation in both pear fruits and calli, and ABA-activated PuABI5 positively regulates stone cell lignification. We demonstrate that ABA-induced PuABI5 binds directly to the PuMYB169 promoter and activates its expression to promote the transcription of PuRBOHF and lignin-related genes, thereby enhancing ROS production and lignin accumulation. Notably, PuABI5 interacted with PuMYB169 to enhance the induction of PuRBOHF expression, leading to elevated levels of H2O2, which feedback to strengthen the interaction between PuABI5 and PuMYB169. Collectively, our findings elucidate that ABA induces ROS-mediated lignification of stone cells in pears by activating the PuABI5-PuMYB169 transcriptional module.

Lignin