Fruit softening significantly impacts the shelf-life and economic value of fruits. Sweet cherries (Prunus avium L.) are particularly prone to damage during transportation due to softening. While ethylene regulates cell wall degradation and fruit softening in various crops, its role and underlying mechanism in sweet cherry softening remain largely unclear. This study demonstrates that 1-aminocyclopropane-1-carboxylic acid (ACC), a key precursor in the synthesis of ethylene, steadily increases throughout sweet cherry fruit development and ripening, while ethylene treatment reduces fruit firmness. Ethylene treatment negatively regulates the transcriptional level of PavSPL7, a gene encoding a plant-specific SQUAMOSA Promoter Binding Protein-Like 7 (SPL) family protein. Overexpression of PavSPL7 suppresses the transcriptional levels of genes involved in cell wall loosening (the expansin A6 gene PavEXPA6), pectin degradation (the pectin methyl esterase gene PavPMEI2 and the pectate lyase gene PavPL8), and ethylene biosynthesis (the ACC synthase gene PavACS7), thereby inhibiting fruit softening. These results suggest that ethylene and PavSPL7 antagonistically regulate fruit softening in sweet cherry through negative feedback loop. It is thus proposed that ethylene promotes pectin degradation by downregulating PavSPL7 expression, thereby facilitating fruit softening. Our work gains insight into molecular mechanism underlying ethylene-mediated regulation of fruit softening in sweet cherry and provides potential targets for manipulation of fruit development and ripening.
Blueberry is an economically important fruit crop, and demand for it is rising. Despite being essential for advancing precision breeding of blueberries, genetic transformation platforms remain limited for transgenic applications. In this study, we used the widely cultivated blueberry cultivar ‘Legacy’ (Vaccinium corymbosum) as the experimental material to establish an efficient adventitious shoot-regeneration system and an Agrobacterium-mediated transformation protocol. Adventitious bud development was promoted via a two-step protocol: induction on WPM medium with 2 mg/L TDZ and 0.5 mg/L NAA, followed by elongation on WPM medium with 3 mg/L ZT. Younger leaves from the shoot tips were selected as explants for the regeneration system. Wounding treatment, placing the abaxial (back) side in contact with the medium, and a 12-d dark treatment at the initial regeneration stage significantly improved the adventitious shoot regeneration rate. Building upon this regeneration system, an Agrobacterium-mediated genetic transformation protocol was developed using a vector carrying the reporter genes enhanced green fluorescent protein (Egfp) and CgRuby1, an anthocyanin-regulating transcription factor from purple pummelo (Citrus grandis). The optimal parameters included culturing Agrobacterium-mediated in liquid medium, preparing the Agrobacterium suspension with an OD600 of 0.8, a 1-h vacuum infiltration, 6 d of co-cultivation, and selection on adventitious shoot regeneration medium containing 10 mg/L kanamycin, which enhanced the regeneration rates of resistant shoots. Polymerase chain reaction (PCR) analysis confirmed that transgenic plants carrying CgRuby1 were achieved with a final transformation efficiency of 6.5%. Phenotypic analysis revealed that the transgenic plants accumulated significantly higher anthocyanin levels in their leaves than the wild-type plants. In addition, key blueberry anthocyanin biosynthetic genes, including VcCHS, VcFHT, VcDFR, VcANS, and VcUFGT, were markedly upregulated in the transgenic lines. Taken together, we have successfully established an efficient transformation system that may hold great potential for functional characterization of genes involved in various processes.
Fresh fruits and vegetables are critical sources of essential nutrients and natural pigments, playing a significant role in human health. However, low-temperature stress represents a major abiotic factor influencing plant growth and development. Exposure to low temperatures during the growing phase can markedly diminish both fruit yield and quality. Additionally, postharvest handling, including transportation, retail, and storage, accelerates senescence and spoilage, resulting in considerable economic losses. Although cold storage effectively reduces respiration rates and prolongs shelf life, improper application can lead to chilling injury in cold-sensitive produce, further exacerbating commercial losses. Chilling injury impairs hormone balance, disrupts cellular membrane integrity, damages photosynthetic function, and alters enzyme activity. This review examines the mechanisms underlying chilling injury and cold resistance in produce. Focusing on recent advances in cold tolerance research, particularly using Arabidopsis thaliana as a model system, it discusses the latest insights into chilling injury. Additionally, the physiological foundation of cold resistance and the role of plant hormones in this process are explored. The conclusion synthesizes identified research gaps, highlights enduring challenges, and proposes directions for future research.
The development of insertion‒deletion (InDel) markers provides a valuable tool for genetic and genomic studies in tea (Camellia sinensis) plants. In this study, 4,370,229 InDel markers were identified through genome resequencing of Lingtou Dancong (BY) and Shuixian 7 (SX7). Transcriptome based on RNA sequencing revealed differential expression of 1,125 genes involved in plant-pathogen interaction pathways. Based on genome resequencing of the two tea varieties with a shared genetic background and RNA-seq dataset for post-anthracnose infection, molecular markers for anthracnose resistance in tea plants were developed by identifying specific InDels within the disease resistance-associated interval. The InDel marker linked to anthracnose resistance was located at 123,508,930 bp on chromosome Chr10. Tea plants with DNA bands of 590-bp or heterozygous bands amplified by the primer were resistant to the disease, while those with 431-bp bands were susceptible. When tested across 206 different tea varieties, the Indel marker CsRc demonstrated an 88.59% genotype–phenotype match, confirming its applicability for detecting anthracnose resistance/susceptibility in tea plants. Additionally, the CsRc marker was found to be located within the serine/threonine protein kinase gene, suggesting that ATP plays a critical role in the metabolic processes of tea plants. Taken together, our findings unravel important Indel markers for efficiently distinguishing valuable tea genotpes with desirable resistance to anthracnose, which holds great potential for facilitating disease resistance breeding in the future.
Iron (Fe), an essential micronutrient for plants, critically influences crop yield and quality. The IRON MAN (IMA) gene family regulates Fe uptake, but its functional role in apple (Malus domestica) remains unclear. This study performed phylogenetic and tissue-specific expression analyses of the MdIMAs gene family in apple under Fe deficiency. Among the MdIMAs genes, MdIMA1 was revealed to act as the key regulatory gene involved in Fe deficiency response. Heterologous expression of MdIMA1 in Arabidopsis thaliana significantly enhanced Fe deficiency tolerance, as manifested by increased fresh weight, chlorophyll content, ferric chelate reductase (FCR) activity, plasma membrane H+-ATPase activity, and Fe concentration. Moreover, genes associated with rhizosphere acidification and Fe transport and absorption were upregulated upon MdIMA1 overexpression, leading to promoted Fe uptake and utilization. Similarly, heterologous expression in tomato improved fresh weight and chlorophyll content, and enhanced both fruit yield and Fe concentration under Fe-deficient conditions. Meanwhile, MdIMA1 overexpression in apple calli resulted in elevated Fe deficiency tolerance through increasing H+-ATPase activity, while silencing MdIMA1 reduced this activity. Collectively, these results indicate that MdIMA1 positively regulates Fe uptake and utilization, providing a valuable target gene of significance for improving Fe nutrition in apples.
Abiotic stress severely restricts plant growth, necessitating swift and, at times, heritable reprogramming of gene expression. To regulate chromatin states and fine-tune stress-responsive pathways, plants rely on four key epigenetic mechanisms: DNA methylation, histone modifications, small RNA-mediated silencing, and chromatin remodeling. Cytosine methylation in CG, CHG, and CHH contexts, mediated by Methyltransferase 1 (MET1), Chromomethylase 3 (CMT3), and Domains Rearranged Methyltransferase 2 (DRM2), controls promoter accessibility, transposable-element activity, and stress-induced transcription at loci such as High-Affinity K⁺ Transporter 1 (HKT1), Nine-cis-epoxycarotenoid dioxygenase 3 (NCED3), and Chromatin Remodeling 12 (CBF). Histone acetylation and methylation are catalyzed by General Control Non-Repressed 5 (GCN5), Arabidopsis Trithorax 1/SET Domain Group (ATX/SDG) methyltransferases, and reversed by Histone Deacetylase/HISTONE DEACETYLASE2C (HDA6/19/HD2C) or Jumonji-C Domain-Containing Protein (JMJ) demethylases. Small RNAs, produced via the RdDM pathway (Pol IV/V, RDR2, DCLs), direct non-CG methylation, enabling rapid and reversible modulation of transcription in ion transporters, ABA signaling genes, and stress-related transcription factors. Chromatin remodelers like Chromatin Remodeling 12 (CHR12) and Pickle Chromatin Remodeler (PKL), alongside epitranscriptomic modifications, such as m6A and m5C (written by MTA/MTB and NSUN2, and erased by ALKBH demethylases), further influence transcript stability, translation, and heat-responsive transposable-element activation. These interconnected processes also generate stress memory, marked by sustained H3K4me3, persistent CHH hypomethylation, and siRNA loss at transposable-element loci, enabling faster reactivation during recurrent stress or, in some cases, transgenerational inheritance. This review offers an integrated framework that links molecular epigenetic mechanisms with adaptive stress physiology and highlights emerging opportunities for epigenetic priming, targeted epigenome editing, and trait engineering to develop climate-resilient crops.
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.
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.
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.