Abstract Grafting is a horticultural strategy for improving crop productivity and tolerance to biotic and abiotic stresses. However, the genetic basis of graft compatibility and its effects on plant growth and fruit metabolism remain poorly understood in tomato. In this study, we systematically evaluated the growth and development of tomato ( Solanum lycopersicum L.) of scions ‘72–69’ grafted onto 14 rootstocks (9 novel F 1 hybrids [GC1–GC9] and 5 commercial cultivars [GC10–GC14]). Based on mature-stage growth and yield performance, the 14 graft combinations were classified into high-compatibility (high-com, GC1–GC5) and low-compatibility (low-com, GC6–GC14) groups. Low-com combinations exhibited reduced vegetative growth and yield, earlier fruit maturation, and structural abnormalities in the scion stem tissues, whereas high-com combinations maintained stronger growth and productivity. Comparative genomic analysis of F 1 rootstocks with contrasting compatibility phenotypes identified 28 candidate genomic regions encompassing 203 genes. Among these, ethylene-overproduction protein 1 ( SlETO1 ) and wall-associated kinase-like ( SlWAKL10 ) contained heterozygous coding variants within conserved domains in the low-com rootstocks, whereas the corresponding loci were homozygous in the high-com rootstocks, suggesting their potential association with graft compatibility. Integrated transcriptomic and metabolomic analyses revealed distinct molecular and metabolic responses between the two graft-compatibility groups. Low-com fruits exhibited enhanced expression of stress- and ethylene-related genes and accumulated substantially higher levels of soluble sugars, including glucose, fructose, and sucrose, whereas high-com fruits showed greater accumulation of organic acids. Correlation analyses further indicated associations between SlWAKL10 and SlETO1 expression and soluble sugar accumulation. Collectively, our work establishes a genetic framework for rootstock-scion compatibility and reveals its systemic effects on fruit metabolism, providing critical insights for molecular breeding of graft-compatible tomato rootstocks.
Climate change has intensified the occurrence of freezing damage in peach (Prunus persica) orchards, particularly during winter dormancy, posing a major threat to sustainable peach production. Prunus davidiana, a close wild relative of peach, exhibits enhanced cold hardiness and represents a valuable genetic resource for breeding cold-tolerant cultivars. However, the mechanism underlying its superior cold adaptation remain largely unknown. In this study, comparative transcriptome analysis of 7 peach and wild relative accessions, combined with genetic transformation approaches, identified SUGARS WILL EVENTUALLY BE EXPORTED TRANSPORTER 7 (SWEET7) as a key regulator of cold tolerance in P. davidiana. PdaSWEET7 was specifically induced by cold stress in P. davidiana and enhanced cold tolerance by facilitating the transport of extracellular glucose into phloem cells, thereby promoting cellular osmotic adjustment. In addition, natural variations were exclusively present in the PdaSWEET7 promoter not only increased its own promoter activity but also interacted with basic leucine zipper 9 (bZIP9) and the myelocytomatosis (MYC) transcription factor MYC2.1 under normal and cold conditions, respectively. Collectively, this study reveals a previously unknown SWEET7-mediated mechanism responsible for cold hardiness in P. davidiana and provides valuable genetic insights for the molecular breeding of cold-tolerant peach cultivars.
The XANTHOMONAS RESISTANCE 21-binding protein 3 (XB3) gene family, encoding proteins with RING-finger or U-box domains, primarily functions as E3 ubiquitin ligases that are crucial for ubiquitin-mediated protein degradation and stress responses. This study presents the first genome-wide identification and characterization of the XB3 family in apple (Malus domestica), revealing 10 members named XBMD3s. Comprehensive analyses of phylogenetic relationships, chromosomal distribution, gene structures, conserved motifs, and promoter cis-acting elements revealed the evolutionary conservation and regulatory complexity of the XBMD3 family. The tissue-specific expression data revealed that XBMD31/31-1/31-2/31-3 and XBMD35 predominantly expressed in roots, whereas XBMD32/32-1, XBMD33/33-1, and XBMD34 exhibited preferential expression in leaves. Furthermore, all XBMD3 genes responded to drought stress, in which XBMD32 showing the strongest transcriptional induction, with an increase by more than 4.3 folds. Functional characterization demonstrated that overexpression of XBMD32 enhanced drought tolerance in transgenic tobacco plants increasing antioxidant enzyme activities and reducing reactive oxygen species (ROS) accumulation. In addition, we obtained XBMD32-overexpressing and XBMD32-silenced apple plants by Agrobacterium-mediated transient genetic transformation. The overexpression plants were more drought tolerant, whereas the silenced plants showed more sensitive phenotypes. Taken together, these findings underscore the role of the XBMD3 family in apple adaptation to drought stress, providing a basis for future functional studies and the improvement of drought tolerance.
Leaf color mutations in plants serve as valuable resources for investigating metabolic pathways related to biosynthesis of chlorophyll, flavonoid, and carotenoid. In this study, a comprehensive analysis of the physiological characteristics, transcriptomes, and metabolomic profiles of a mutant of Malus hupehensis var. pingyiensis with red leaves (RM) and normal plant (CK) with green leaves was performed. A total of 283 differentially abundant metabolites (DAMs) and 9,822 differentially expressed genes (DEGs) were identified between RM and CK. Compared with the CK, RM presented a reduced chlorophyll content and elevated levels of carotenoids, flavonoids, and anthocyanins. KEGG pathway enrichment analysis revealed that the DAMs and DEGs were associated mainly with the metabolism of chlorophyll, carotenoids, and flavonoids, with the anthocyanidin biosynthesis pathway showing the greatest enrichment. Several key anthocyanin biosynthetic genes, including chalcone isomerase (CHI), dihydroflavonol 4-reductase (DFR), UDP-Glucose:Flavonoid 3-O-Glucosyltransferase (UFGT), and UDP-glycosyltransferases (UGT), were upregulated in the red leaves, in line with a significant increase in cyanidin 3-O-glucoside (C3G) and pelargonidin 3-O-glucoside (pg3G). Furthermore, RNA sequencing (RNA-seq) analysis revealed upregulation of MdMYB10 and MdUFGT. Yeast one-hybrid (Y1H), chromatin immunoprecipitation (ChIP), and dual-luciferase reporter (LUC) assays demonstrated that MdMYB10 bound to the MdUFGT promoter fragment and subsequently upregulated its expression, leading to the accumulation of C3G and pg3G in RM. Our findings provide new insights into the regulatory mechanisms of leaf coloration and offer a foundation for the development of new cultivars with alteration of leaf color.
Climate change and soil degradation pose increasingly serious threats to global food security, highlighting the need for continued innovation and diversification in plant breeding strategies. Plant growth and development rely on precise and dynamic regulation of gene expression that enables rapid responses to environmental cues. Increasing evidence highlights the central roles of cis-regulatory elements (CREs), including RNA sequence motifs, RNA modifications, and secondary or tertiary RNA structures, in post-transcriptional control. These CREs are enriched within the untranslated regions (UTRs) of plant mRNAs. In this review, we summarize the diverse CREs characterized to date, particularly those located within the 3′UTR, and describe how they function together with trans-acting factors like RNA-binding proteins to regulate mRNA stability, translation efficiency, subcellular localization, and non-cell-autonomous mobility. These processes constitute key mechanisms for the spatiotemporal regulation of gene expression that underlies plant environmental responses and resilience. We further discuss emerging opportunities and challenges in harnessing 3′UTR CREs as targets and tools for next-generation crop improvement. By integrating recent advances in post-transcriptional biology with molecular breeding frameworks, 3′UTR CREs offer a promising framework for achieving precise, tunable, and robust regulation of agronomically important traits.
Waterlogging (WL) stress severely affects the growth and productivity of fruit crops. Cytosolic calcium (Ca2+) is recognized as a secondary messenger that initiates adaptive responses to environmental stresses. However, the mechanisms by which exogenously applied Ca2+ enhances WL tolerance remain poorly understood. In this study, we investigated whether exogenous Ca2+, applied as calcium chloride (CaCl2) and calcium oxide nanoparticles (CaO-NPs), might mitigate WL-induced damage in peach (Prunus persica) seedlings. We found that both Ca2+ formulations significantly alleviated WL-induced growth inhibition, restored photosynthetic efficiency, and maintained root system architecture and metabolic activity. Two Ca2+ treatments markedly reduced intracellular superoxide (SOD) and hydrogen peroxide accumulation, thus attenuating membrane lipid peroxidation and electrolyte leakage. Hormonal profiling demonstrated that Ca2+ suppressed excessive abscisic acid and salicylic acid accumulation while restoring jasmonate homeostasis under WL conditions. Furthermore, at the transcriptional level, Ca2+ enhanced stress tolerance by upregulating the expression of genes encoding antioxidant (PpSOD; and peroxidase, PpPOD), photosynthetic (photosystem II subunit Q, PpPsbQ; and photosystem I subunit K, PpPsaK), and Ca2+ (CBL-interacting protein kinases, PpCIPK5 and PpCIPK11). In line with reduced oxidative stress, Ca2+ also adaptively downregulated genes related to the fermentative pathway (alcohol dehydrogenase, PpADH; and lactate dehydrogenase, PpLDH), indicating a shift away from anaerobic metabolism. Notably, comparative analysis revealed that ionic Ca2+ and CaO-NP treatments resulted in largely similar outcomes under WL conditions, with only marginal differences in some parameters. Taken together, these results indicate that Ca2+-associated signaling is a putative regulatory network underlying adaptive responses to WL stress in woody fruit crops.
Zhangjiajie vine tea, derived from Ampelopsis grossedentata, is a characteristic product with pharmacological benefits for heat clearance, detoxification, liver calming, and blood pressure reduction. The content of dihydromyricetin (DMY), the primary active compound, directly affects product quality, yet the regulatory genes associated with high DMY contents remained to be determined. In this study, a total of 164 vine tea germplasms collected from Zhangjiajie were revealed to exhibit substantial variation in DMY contents, ranging from 13.96 to 41.56
Kiwifruit (Actinidia arguta) is an economically important horticultural crop worldwide with remarkably high nutritional value. However, the dynamic metabolic changes underlying fruit quality during kiwifruit ripening remain poorly understood. In this study, integrated metabolomic and transcriptomic analyses were conducted to explore the molecular basis of fruit quality across three ripening stages in three A. arguta varieties with distinct flesh characteristics: ‘Kokuwa’ (full-green flesh), ‘Xianziguang’ (red flesh), and ‘Qinghuang’ (yellow flesh). A total of 371 differentially accumulated metabolites and their coexpressed genes were classified into six distinct metabolite vs gene modules. Several metabolites, including five sugars, eight organic acids, four volatile compounds, and seventeen flavonoids, such as anthocyanins, procyanidins, and flavones, were further identified as key contributors to fruit quality formation. By integrating gene coexpression network analysis with metabolomic data, we identified a range of ripening-related genes and transcription factors involved in the biosynthesis of sugars, organic acids, anthocyanins, and the L-ascorbic acid metabolic pathway. Notably, thirteen structural genes involved in anthocyanin biosynthesis—anthocyanidin reductase (2), dihydroflavonol 4-reductase (4), flavonol synthase (5), and phenylalanine ammonia-lyase (2), were strongly correlated with multiple transcription factors, indicating that a complex regulatory network governed anthocyanin biosynthesis in A. arguta. This study provides new insights into the molecular basis of metabolite variation in kiwifruit and highlights the potential of genetic information for improving fruit quality.
Abstract Phosphate transporters (PHTs) are H2PO4 ⁻/H+ transporters that facilitate inorganic phosphate uptake from the soil and its distribution within plants. In citrus, seasonal summer drought constrains yield and limits phosphate uptake. However, the roles of PHT genes in drought response remain poorly understood. In this study, we identified 20 PtPHTs in the Poncirus trifoliata genome and classified them into five subgroups (I to V) based on phylogenetic relationships. Promoter analysis revealed abundant cis-acting elements associated with abiotic stress and phytohormone responses, while synteny analysis indicated that gene duplication contributed to PtPHT family expansion. Expression profile showed that several genes, including PtPHT1;1, PtPHT1;2, PtPHT1;3, PtPHT3;3, PtPHT4;3, PtPHT5;1, and PtPHT5;2 were significantly upregulated by drought, with PtPHT1;2 exhibiting the strongest response (about 16.4 folds). Silencing PtPHT1;2 markedly reduced phosphorus (P) accumulation in transgenic citrus calli, confirming its functional role in inorganic phosphate uptake. Yeast one-hybrid (Y1H) screening identified Related to AP2.12 (PtRap2.12), an APETALA2/ETHYLENE RESPONSE FACTOR (AP2/ERF) transcription factor, as an upstream regulator of PtPHT1;2. This interaction was validated by Y1H and dual-luciferase assays, demonstrating that PtRap2.12 directly binds to and activates the PtPHT1;2 promoter. Functional analysis further showed that overexpression of PtRap2.12 enhances drought tolerance of transgenic plants, as indicated by improved growth, reduced membrane damage, elevated antioxidant enzyme activities, and increased P accumulation. Moreover, transgenic plants displayed upregulated expression of NtPHT1;1 in shoots and NtPHT1;4 in roots of tobacco (Nicotiana tabacum) under drought conditions. In summary, this study provides a comprehensive analysis of PtPHT genes in P. trifoliata and highlights the role of the PtRap2.12–PtPHT1;2 module in regulating both phosphate uptake and drought tolerance, offering a theoretical basis for breeding citrus rootstocks with enhanced resistance to drought and phosphate deficiency.
Abstract Malate is a key determinant of peach (Prunus persica L.) fruit acidity and quality. Vacuolar H⁺-ATPase (VHA) contributes to malate accumulation in plants, but its function in peach fruit remains unclear. In this study, we identified 23 PpVHA genes in the ‘Zhongyoutao 14’ (CN14) peach genome and manually adjusted three gene models using transcriptome data. Sequence alignment and phylogenetic analysis revealed that each VHA subunit is encoded by at least one gene in peach. Based on malate content, PpVHA-c1 and PpVHA-c3 were selected as candidate genes potentially involved in malate accumulation. Transient transgenic assays revealed that both PpVHA-c1 and PpVHA-c3 promote malate accumulation in peach fruit and Nicotiana benthamiana leaves. Furthermore, we predicted nine and fourteen transcription factors as potential positive regulators of PpVHA-c1 and PpVHA-c3, respectively. These findings demonstrate that PpVHA-c1 and PpVHA-c3 function as positive regulators of malate accumulation, providing a foundation for dissecting the regulatory network controlling VHA-mediated organic acid metabolism in peach fruit.
Internal cavity formation followed by gum-like substance (GM) accumulation is a frequent quality disorder in mature ‘Fengtangli’ plum fruits, but the underlying physiological and molecular processes remain unclear. Here, we integrated widely targeted metabolomics, transcriptomics, and hormone profiling of GM, cavity-adjacent flesh (CF), and normal flesh (NF). Both GM and CF predominantly accumulated a range of secondary metabolites involved in stress response, including flavonoids, phenolic acids, and terpenoids. Compared with NF, CF exhibited significant reduction of glucose and fructose, along with increased L-malic acid, tartaric acid, and maslinic acid, and decreased cis-aconitic acid and neochlorogenic acid. These changes suggest substantial carbon redistribution that may also influence flavor. Hormone measurements further revealed a coordinated shift of signaling pathways in CF, marked by reduced auxin (IAA), cytokinins (CKs), and gibberellins and by increased jasmonic acid, salicylic acid, and abscisic acid. Consistently, CF exhibited enhanced oxidative- and defense-associated responses, including higher peroxidase activity, increased lignin deposition, and accumulation of phenylpropanoid-derived compounds. Transcriptome analysis showed that differentially expressed genes in CF were implicated in hormone signal transduction, sugar metabolism, and phenylpropanoid/flavonoid pathways. Collectively, these results demonstrate that cavity formation in plum flesh triggers carbon reallocation, secondary metabolite enrichment, and activation of defense-related pathways, providing new insight into tissue adaptation following internal cracking and gum development.
Ca2+ deficiency causes irreversible physiological disorders that markedly reduce the yield and quality of many horticultural crops, leading to substantial economic losses. Tip burn in Chinese cabbage (Brassica rapa ssp. pekinensis) is associated with Ca2+ deficiency; however, the underlying molecular mechanisms remain poorly understood. In this study, Ca2+ deficiency suppressed growth and impaired photosynthetic performance in Chinese cabbage seedlings. Under Ca2+ deficiency, cytosolic Ca2+ levels decreased, accompanied by excessive reactive oxygen species (ROS) accumulation in the leaves. Foliar application of dimethylthiourea (DMTU), an ROS scavenger, alleviated Ca2+ deficiency-induced tip burn by reducing ROS accumulation. RNA-seq analysis further revealed significant enrichment of the mitogen-activated protein kinase signaling and plant hormone signal transduction pathways during tip-burn development. Several differentially expressed genes associated with these pathways were identified as responsive to Ca2+ deficiency. Compared with normal Ca2+ and DMTU-rescued conditions, the respiratory burst oxidase homolog D (BrRbohD-2) gene was markedly upregulated under Ca2+ deficiency. Overexpression of BrRbohD-2 increased ROS accumulation and aggravated tip burn in Chinese cabbage seedlings, whereas its suppression reduced ROS levels and alleviated tip burn. These findings provide important insights into the role of BrRbohD-2 and the regulatory mechanisms underlying Ca2+ deficiency-related disorders in Brassicaceae crops.
Abstract Selenium (Se) biofortification in forage tree species offers a sustainable strategy to improve nutritional quality. This study investigated the physiological and molecular responses of Broussonetia papyrifera, a high-biomass woody species, to exogenous selenite (Na2SeO3) and selenate (Na2SeO4). Low Se concentrations (≤ 0.4 mM) significantly enhanced plant growth, while higher concentrations (0.8 mM), especially Na2SeO4, inhibited biomass accumulation in a dose-dependent manner. Both forms of Se substantially increased foliar Se content, with Na2SeO4 showing higher uptake efficiency. Genome-wide screening identified four sulfate/Na2SeO4 assimilation-related genes including ATP sulfurylase 1 (BpAPS1), BpAPS2, adenosine 5′-phosphosulfate reductase (BpAPR1), and BpAPR2. Phylogenetic analyses confirmed the evolutionary conservation of these proteins, which were localized to the chloroplasts. Tissue-specific expression patterns revealed a positive correlation between transcript levels of BpAPS1, BpAPR1, and BpAPR2 and Se content, while BpAPS2 expression was inversely correlated, indicating functional divergence. Compared to wild-type (WT) plants, transgenic Arabidopsis thaliana lines overexpressing these genes accumulated 1.27- to 1.60-fold more Se under Na2SeO4 stress, accompanied by coordinated upregulation of key endogenous Se metabolism genes like AtAPS, AtAPR, S-adenosylmethionine carriers 3 (AtSAM), homocysteine S-methyltransferase (AtHMT), methylselenol methyltransferase (AtMMT), suggesting enhanced Se assimilation and detoxification capacity. Collectively, these findings clarify the functional roles of the APS and APR gene families in Se uptake, assimilation, and detoxification in a woody crop, highlighting potential genetic targets for Se biofortification.
Abstract Actinidia rufa is a valuable species for hybridization and introgressive breeding of new kiwifruit cultivars due to its exceptional tolerance to waterlogging. In this study, a chromosome-level genome of A. rufa was assembled using Illumina short-read and PacBio Continuous Long Read (CLR) sequencing technologies. The assembled genome spans 613.66 Mb with an N50 of 3.06 Mb, and 94 scaffolds were anchored to 29 pseudochromosomes. A total of 42,484 protein-coding genes and 267.26 Mb of repetitive sequences, accounting for 49.08% of the genome, were identified. Phylogenetic analysis demonstrated a close evolutionary relationship between A. rufa and A. chinensis, with their most recent common ancestor being estimated to diverge around 7 million years ago. Demographic analysis indicated a historical population expansion in A. rufa, whose current suitable habitats are primarily found in the Japanese archipelago and Taiwan, China. Comparative genomic analysis revealed large-scale structural variations, including a chromosomal region on Chr19 in A. rufa that corresponds to two distinct segments on Chr2 and Chr9 in A. chinensis. Additionally, A. rufa cv. ‘MTS7001’ exhibited superior waterlogging tolerance compared to A. chinensis cv. ‘Donghong’. Gene expression analysis showed that, in response to early waterlogging stress, A. rufa exhibited upregulation of genes associated with energy metabolism and signaling of hormones, including those related to auxin, abscisic acid, and brassinosteroids, compared to A. chinensis. This study provides genomic insights into the genetic basis of exceptional waterlogging tolerance in A. rufa, contributing to molecular breeding efforts in kiwifruits in the future.
Abstract Superficial scald is a physiological disorder in apples (Malus domestica). A two-year study was performed to investigate the relationship between α-farnesene, ethylene, and superficial scald in ‘White Winter Pearmain’ apples. In the first year, untreated apples were stored at 0°C for 12 weeks in an observational experiment. Results indicated that the expression of ethylene perception genes and α-farnesene metabolism-related genes correlated with the onset of superficial scald. The second year involved an interventional study, where apples were treated with 1.25 mM lovastatin (LOV), 1.4 mM ethephon, and 700 mM 1-methylcyclopropene (1-MCP), prior to storage at 0°C for 12 weeks. After the storage, both LOV and 1-MCP significantly reduced α-farnesene, conjugated trienols (CTols), and ethylene levels, as well as the incidence of superficial scald, whereas flesh firmness was enhanced. The combination of LOV and 1-MCP showed the most pronounced effect, as justified by pronounced alterations in the relative expression levels of α-farnesene- and ethylene-related genes (α-farnesene synthase, MdAFS; 1-aminocyclopropane-1-carboxylate synthase 1, MdACS1; MdACS4; MdACS5B; 1-aminocyclopropane-1-carboxylate oxidase 1, MdACO1; MdACO5; MdACO7; ethylene receptor 5, MdETR5; MdETRS2; and MdETR102) during storage. Correlation analysis showed a strong association between CTol content, ethylene production rate (EPR), and the expression of MdAFS, MdACS4, MdACS5A, MdACS5B, MdACS7, MdACO1, MdACO5, and MdETRS2 with superficial scald occurrence. These findings offer new insights into the molecular mechanisms by which α-farnesene and ethylene influence superficial scald development.
Abstract Fruit softening is a critical determinant of shelf life and quality of apples (Malus domestica). While the degradation of cell wall components is a well-established driver of this process, the specific involvement of brassinosteroids (BRs) in postharvest apple softening and how their upstream regulators influence cell wall integrity perception remain unclear. In this study, transcriptomic analysis identified EXORDIUM (MdEXO) as a gene whose expression declined during storage. Real-time quantitative PCR (RT–qPCR) assays and in situ hybridization confirmed this downregulation and revealed a positive correlation between MdEXO expression level and fruit firmness. Further characterization showed that the MdEXO protein was phosphate-responsive and localized to the cell wall. Functional studies demonstrated that overexpression of MdEXO significantly enhanced fruit firmness, increased protopectin and cellulose content, and reduced soluble pectin levels. These changes were accompanied by the downregulation of key cell wall degradation-related genes, including polygalacturonase 1 (MdPG1), pectate lyase 5 (MdPL5), and β-galactosidase 9 (Mdβ-Gal9). Additionally, MdEXO overexpression increased endogenous BR levels by upregulating the BR biosynthetic gene DWARF 4 (MdDWF4). On the contrary, treatment with brassinazole (BRZ), the BR biosynthesis inhibitor attenuated the firmness-promoting effect of MdEXO overexpression. Furthermore, VIGS-mediated transient silencing of MdEXO in apple fruits produced the opposite phenotypic effects compared to the overexpression lines. These results demonstrate that MdEXO delays apple fruit softening by modulating BR biosynthesis, offering new insights into the hormonal regulation of postharvest fruit quality.
Abstract The sequencing of the Capsicum genus pangenome has stimulated interest in biotechnological strategies aimed at modulating pungency levels. While promising, such approaches require a comprehensive understanding of the ecological and physiological roles of capsaicinoids—the alkaloids responsible for pepper pungency. Although traditionally considered a defense against mammalian seed predators, accumulating evidence indicates that capsaicinoid biosynthesis is integrated into broader stress-response networks. Capsaicinoid production is influenced by genetic, ecological, and environmental factors, including light intensity, temperature, drought, and mineral nutrition, which dynamically regulate the biosynthetic pathway. Beyond defense, capsaicinoids perform internal physiological functions such as antioxidant protection, redox buffering, and nitrogen assimilation, framing pungency as a component of a coordinated metabolic strategy rather than a singular defensive trait. By connecting ecological pressures with molecular regulation, the dual ecological and physiological roles of capsaicinoid biosynthesis are emphasized, while knowledge gaps remain, particularly regarding non-Directed Deterrence Hypothesis (DDH) functions and tissue-specific expression of capsaicinoid genes. This integrated perspective provides a foundation for biotechnological interventions that modulate pungency without compromising plant resilience or metabolic homeostasis.
Abstract Gibberellins (GAs) play a critical role in regulating the balance between vegetative and reproductive growth in strawberries; however, the underlying molecular mechanisms remain largely unclear. In this study, a weekly foliar application of GA3 was performed to plugs of the short-day strawberry cultivar ‘Ninglu’ (Fragaria × ananassa). During the vegetative growth stage, GA3 treatment increased plant height by 57.7% and mean petiole length by 69.4%, in addition to enhancing the expansion of the leaf lamina and vascular tissues. Developmental analysis of the shoot apical meristem (SAM) revealed that GA3 delayed floral transition: while all control plants initiated flower buds within 40 days, only 77% of GA3-treated plants did so. Transcriptional analysis showed that GA3 significantly upregulated the expression of photoperiod-related genes in leaves, including GIGANTEA (GI), CONSTANS (CO), and FLOWERING LOCUS T 1 (FT1), which activated floral integrators such as SUPPRESSOR OF OVEREXPRESSION OF CO 1 (SOC1) and TERMINAL FLOWER 1 (TFL1). These changes subsequently suppressed key floral activators (APETALA1, AP1; FRUITFULL, FUL; and LEAFY, LFY) in the SAM. Additionally, GA3 influenced nitrogen partitioning in leaves by modulating the expression of genes associated with nitrogen metabolism (NITRATE REDUCTASE, NR; NITRITE REDUCTASE, NIR; GLUTAMINE SYNTHETASE, GS; and FD-GOGAT, GOGAT), transport (NITRATE TRANSPORTER 1.2/1.7, NRT1.2/NRT1.7; and AMMONIUM TRANSPORTER 1.1, AMT1.1), and flowering time control (FERREDOXIN-NADP( +)OXIDOREDUCTASE 1, FNR1; and CRYPTOCHROME 1, CRY1). These results suggest that GA3 may delay floral transition in strawberries through the coordinated modulation of vegetative growth, photoperiod signaling, and nitrogen metabolism, providing mechanistic insights into GA-mediated flowering control and offering potential implications for cultivation management.
Plant elicitor peptides (Peps) are conserved damage-associated molecular patterns (DAMPs) that regulate plant immunity and growth, but their roles in citrus, a major economically important fruit crop, remain underexplored. A pangenome analysis of 15 Aurantioideae species identified 17 PRECURSOR OF PEP (PROPEP) genes encoding 22-amino-acid mature Peps with conserved receptor-binding motifs. Expression analysis demonstrated that Citrus sinensis PROPEP (CsPROPEP) and its receptor CsPEPR were significantly modulated by infection with Xanthomonas citri subsp. citri (Xcc), the causal pathogen for citrus canker disease and by phytohormones, including jasmonic acid (JA) and salicylic acid (SA). Supplementing the regeneration medium with 0.01 nM CsPep boosted shoot regeneration efficiency during genetic transformation by 2.43- to 3.21-fold in Citrus sinensis. Likewise, adding CsPep to the Agrobacterium rhizogenes infection solution enhanced root development in stem cuttings, increasing lateral root numbers by 2.23- to 2.98-fold and maximum root length by 1.74- to 2.59-fold. This growth-promoting effect was conserved across other citrus species, including pummelo and lemon. Furthermore, both exogenous application of CsPep and transient overexpression of CsPROPEP activated citrus immune responses, conferring enhanced resistance to citrus canker. These findings highlight the dual role of CsPep in activating immune defenses and promoting regeneration, bridging a critical gap in DAMP peptide signaling in citrus. Our findings offer a peptide-based strategy for sustainable canker management and improved genetic transformation efficiency.
Fruit ripening and quality formation are complex biological processes governed by multiple layers of regulatory mechanisms, including transcriptional regulation, translational control, and post-translational modifications (PTMs). While transcriptional and translational regulations have been extensively studied, PTMs are increasingly recognized as equally vital regulators. As a key regulatory mechanism in plant cells, PTMs enable rapid and targeted functional modulation. These modifications involve the covalent alteration of proteins, influencing their synthesis, localization, stability, and functionality. This review summarizes recent advancements in the study of major PTMs—such as protein phosphorylation, ubiquitination, histone acetylation, histone methylation, and glycosylation—and their roles in regulating fruit ripening and quality formation. Additionally, we also highlight a number of lesser-known PTMs, including lactylation and crotonylation, in these processes. This review not only offers new perspectives for enhancing the post-translational regulatory network of fruit ripening but also provides a theoretical foundation and novel insights for improving fruit quality and postharvest storage.
