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.