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This study evaluated the salt tolerance in 40 celery germplasm resources to clarify the different salt tolerances of celery germplasm. A gradient treatment with different concentrations of NaCl solutions (100, 200, and 300 mmol·L−1) was used to simulate salt stress. After 15 days of salt treatment, 14 indicators related to plant growth, physiology, and biochemistry were determined. The results showed that different celery varieties responded differently to salt stress. Notably, there were significant variations in below-ground dry weight, root–crown ratio, antioxidant enzyme activity, and soluble protein content among the accessions under salt stress. Principal component analysis was used to identify important indices for evaluating salt tolerance, including plant height, spread, content of soluble protein, and so on. A comprehensive evaluation was conducted utilizing the salt damage index, principal component analysis, affiliation function analysis, and cluster analysis. The 40 celery germplasms were classified into five highly salt-tolerant, seven salt-tolerant, fifteen moderately salt-tolerant, nine salt-sensitive, and four highly salt-sensitive germplasms. SHHXQ, MXKQ, XBQC, XQ, and TGCXBQ were highly salt-tolerant germplasms, and BFMSGQ, HNXQ, ZQ, and MGXQW were highly salt-sensitive germplasms. The results of this study provide a reference for the variety of celery cultivation in saline areas and lay a foundation for the selection and breeding of salt-tolerant varieties of celery. [ABSTRACT FROM AUTHOR]

To clarify the impact of continuous dark stress on lignin and cellulose synthesis in celery, shade-tolerant celery varieties were screened. Yellow celery variety 'Qianhuang No.1' and green celery variety 'Qianlv No.1' were separately grown in vegetable greenhouses. Dark treatments were applied using PVC shading sleeves for 4, 8, 12, and 16 d after celery had grown 10–13 true leaf blades. This study aimed to investigate the impact of varying periods of dark treatment on the morphological characteristics, lignin accumulation, and cellulose accumulation in celery. The results showed that dark treatment led to celery yellowing, a reduced stem thickness, and an increased plant height. Analysis of lignin and cellulose contents, as well as the expression of related genes, showed that dark treatment caused down-regulation of AgLAC, AgC3′H, AgCCR, AgPOD and AgCAD genes, leading to changes in lignin accumulation. Dark treatment inhibited the expression of the AgCesA6 gene, thus affecting cellulose synthesis. Under dark conditions, the expression of AgF5H and AgHCT genes had little effect on lignin content in celery, and the expression of the AgCslD3 gene had little effect on cellulose content. Analysis of morphological characteristics, lignin accumulation and cellulose accumulation after different lengths of dark treatment demonstrated that 'Qianlv No.1' is a shade-tolerant variety in contrast to 'Qianhuang No.1'. [ABSTRACT FROM AUTHOR]

The genus Apium, belonging to the family Apiaceae, comprises roughly 20 species. Only two species, Apium graveolens and Apium leptophyllum, are available in China and are both rich in nutrients and have favorable medicinal properties. However, the lack of genomic data has severely constrained the study of genetics and evolution in Apium plants. In this study, Illumina NovaSeq 6000 and Nanopore sequencing platforms were employed to identify the mitochondrial genomes of A. graveolens and A. leptophyllum. The complete lengths of the mitochondrial genomes of A. graveolens and A. leptophyllum were 263,017 bp and 260,164 bp, respectively, and contained 39 and 36 protein-coding genes, five and six rRNA genes, and 19 and 20 tRNA genes. Consistent with most angiosperms, both A. graveolens and A. leptophyllum showed a preference for codons encoding leucine (Leu). In the mitochondrial genome of A. graveolens, 335 SSRs were detected, which is higher than the 196 SSRs found in the mitochondrial genome of A. leptophyllum. Studies have shown that the most common RNA editing type is C-to-U, but, in our study, both A. graveolens and A. leptophyllum exhibited the U-C editing type. Furthermore, the transfer of the mitochondrial genomes of A. graveolens and A. leptophyllum into the chloroplast genomes revealed homologous sequences, accounting for 8.14% and 4.89% of the mitochondrial genome, respectively. Lastly, in comparing the mitochondrial genomes of 29 species, it was found that A. graveolens, A. leptophyllum, and Daucus carota form a sister group with a support rate of 100%. Overall, this investigation furnishes extensive insights into the mitochondrial genomes of A. graveolens and A. leptophyllum, thereby enhancing comprehension of the traits and evolutionary patterns within the Apium genus. Additionally, it offers supplementary data for evolutionary and comparative genomic analyses of other species within the Apiaceae family. [ABSTRACT FROM AUTHOR]

Celery (Apium graveolens L.) is an important vegetable crop cultivated worldwide for its medicinal properties and distinctive flavor. Volatile organic compound (VOC) analysis is a valuable tool for the identification and classification of species. Currently, less research has been conducted on aroma compounds in different celery varieties and colors. In this study, five different colored celery were quantitatively analyzed for VOCs using HS-SPME, GC-MS determination, and stoichiometry methods. The result revealed that γ-terpinene, d-limonene, 2-hexenal,-(E)-, and β-myrcene contributed primarily to the celery aroma. The composition of compounds in celery exhibited a correlation not only with the color of the variety, with green celery displaying a higher concentration compared with other varieties, but also with the specific organ, whereby the content and distribution of volatile compounds were primarily influenced by the leaf rather than the petiole. Seven key genes influencing terpenoid synthesis were screened to detect expression levels. Most of the genes exhibited higher expression in leaves than petioles. In addition, some genes, particularly AgDXS and AgIDI, have higher expression levels in celery than other genes, thereby influencing the regulation of terpenoid synthesis through the MEP and MVA pathways, such as hydrocarbon monoterpenes. This study identified the characteristics of flavor compounds and key aroma components in different colored celery varieties and explored key genes involved in the regulation of terpenoid synthesis, laying a theoretical foundation for understanding flavor chemistry and improving its quality. [ABSTRACT FROM AUTHOR]

Protoplast culture and transformation technology offer a novel method for developing new plant varieties. Nonetheless, the effective preparation of protoplasts and transformation technology specific to celery has yet to be achieved. This study utilized celery seedling leaves as the primary materials to examine the key factors influencing protoplast isolation. The aim was to prepare leaf protoplasts with a high yield and of high quality and subsequently conduct transient gene transformation and expression. The findings indicated that the most effective procedure for isolating and purifying protoplasts was enzymatic digestion using an enzyme solution consisting of 2.0% cellulase, 0.1% pectolase, and 0.6 M mannitol for a duration of 8 h. Subsequently, the protoplasts were filtered through a 400-mesh sieve and purified through centrifugation at 200× g. Within this system, the overall protoplast yield was exceptionally high, reaching a viability rate of up to 95%. The transient transformation system yielded a maximum transformation efficiency of approximately 53%, as evaluated using the green fluorescent protein (GFP) as a reporter gene. The parameters of the transient transformation system were as follows: a protoplast concentration of 5 × 105 cells·mL−1, exogenous DNA concentration of 500 μg·mL−1, final concentration of PEG4000 at 40%, and transformation duration of 15 min. The transient transformation system was also utilized to further analyze the protein localization characteristics of the celery transcription factor AgMYB80. The findings indicated that AgMYB80 predominantly localizes in the nucleus, thereby confirming the reliability and effectiveness of the transient transformation system. This study successfully established an efficient system for isolating, purifying, and transforming celery protoplasts, and will serve as a basis for future studies on molecular biology and gene function. [ABSTRACT FROM AUTHOR]

The plant mitochondria play a crucial role in various cellular energy synthesis and conversion processes and are essential for plant growth. Watercress (Oenanthe javanica) is a fast-growing vegetable with strong adaptability and wide cultivation range, and it possesses high nutritional value. In our study, we assembled the O. javanica mitochondrial genome using the Illumina and Nanopore sequencing platforms. The results revealed that the mitochondrial genome map of watercress has a circular structure of 384,074 bp, containing 28 tRNA genes, 3 rRNA genes, and 34 protein-coding genes. A total of 87 SSR (simple sequence repeat) loci were detected, with 99% composed of palindrome repeats and forward repeats, while no complementary repeats were identified. Codon preference analysis indicated that watercress prefers to use codons encoding leucine, isoleucine, and serine with a preference for A/U-ending codons. Phylogenetic analysis showed that watercress is closely related to species of Bupleurum, Apium, Angelica, and Daucus, with the closest evolutionary relationship observed with Saposhnikovia divaricata and Apium graveolens. This study provides a valuable resource for the study of the evolution and molecular breeding of watercress. [ABSTRACT FROM AUTHOR]

Melatonin (MT) is crucial in plant growth, development, and response to stress. Celery is a vegetable that grows in a cool climate, and a hot climate can deteriorate its growth, yield, and quality. This study investigates the effect of exogenous melatonin on celery physiology. Transcriptional levels were analyzed by spraying celery with exogenous MT before exposing it to high temperatures. The regulatory mechanism of exogenous MT-mediated heat tolerance was examined. The results show that the exogenous MT reduced the thermal damage state of celery seedlings, as well as the malondialdehyde (MDA) content and relative conductivity (REC), increasing the oxidase activity, the osmotic regulatory substances, and chlorophyll, enhancing the leaf transpiration and the light energy utilization efficiency. We examined the mechanism of exogenous MT in mitigating high-temperature damage using the transcriptome sequencing method. A total of 134 genes were expressed differently at high temperature in the celery treated with MT compared with the untreated celery. Functional annotation analysis revealed that the differentially expressed genes were abundant in the "pyruvate metabolism" pathway and the "peroxidase activity" pathway. According to the pathway-based gene expression analysis, exogenous MT can inhibit the upregulation of pyruvate synthesis genes and the downregulation of pyruvate consumption genes, preventing the accumulated pyruvate from rapidly upregulating the expression of peroxidase genes, and thereby enhancing peroxidase activity. RT-qPCR verification showed a rising encoding peroxidase gene expression under MT treatment. The gene expression pattern involved in pyruvate anabolism and metabolism agreed with the abundant transcriptome expression, validating the physiological index results. These results indicate that the application of exogenous MT to celery significantly enhances the ability of plant to remove reactive oxygen species (ROS) in response to heat stress, thereby improving the ability of plant to resist heat stress. The results of this study provide a theoretical basis for the use of MT to alleviate the damage caused by heat stress in plant growth and development. [ABSTRACT FROM AUTHOR]

Celery is one of the mainly consumed leafy vegetables worldwide, however, its short postharvest freshness severely limits its storage and marketing. Studying the post-harvest biology and preservation techniques is important for storing celery products. This study investigated the effect of exogenous GR24 on the quality and flavor of celery during post-harvest storage. The results showed that GR24 can extend the storage life, reduce the decay and chlorophyll degradation, maintain the integrity of petiole cell morphology, and effectively maintain the contents of soluble protein, total phenols, Vc, and DPPH radical scavenging. The HS-SPME-GC/MS results showed that GR24 effectively maintained the levels of flavor compounds, especially D-Limonene, β-Pinene, beta-selinene, caryophyllene, and trans-β-Ocimene, which contribute to the special flavor of celery. Moreover, the application of an exogenous 2.0 µM GR24 solution resulted in elevated gene expression levels of AgGGPPS and AgTPS in the terpenoid pathway, thereby preserving the terpenoid content of D-Limonene, Terpinolene, and α-Copaene throughout the storage period. Consequently, spraying 2.0 µM GR24 was the most effective concentration for maintaining the sensory quality, nutritional quality, and flavor of celery during storage. [Display omitted] • Post-harvest application of GR24 improve the nutritional quality of celery products, with the 2.0 μM treatment being the most effective. • GR24 effectively maintained the levels of flavor compounds of celery during storage. • D-Limonene, β-Pinene, beta-selinene contribute to the special flavor of celery. [ABSTRACT FROM AUTHOR]

Celery is an important leafy vegetable that can grow during the cool season and does not tolerate high temperatures. Heat stress is widely acknowledged as one of the main abiotic stresses affecting the growth and yield of celery. The morphological and physiological indices of celery were investigated in the present study to explore the physiological mechanisms in response to high temperatures. Results showed that the antioxidant enzyme activity, proline, relative conductivity, and malondialdehyde were increased, while chlorophyll and the water content of leaves decreased under high-temperature conditions. Short-term heat treatment increased the stomatal conductance to cool off the leaves by transpiration; however, long-term heat treatment led to stomatal closure to prevent leaf dehydration. In addition, high temperature caused a disordered arrangement of palisade tissue and a loose arrangement of spongy tissue in celery leaves. Combined metabolomic and transcriptomic analyses were further used to reveal the regulatory mechanisms in response to heat stress at the molecular level in celery. A total of 1003 differential metabolites were identified and significantly enriched in amino acid metabolism and the tricarboxilic acid (TCA) cycle. Transcriptome sequencing detected 24,264 different genes, including multiple transcription factor families such as HSF, WRKY, MYB, AP2, bZIP, and bHLH family members that were significantly upregulated in response to heat stress, suggesting that these genes were involved in the response to heat stress. In addition, transcriptional and metabolic pathway analyses showed that heat stress inhibited the glycolysis pathway and delayed the TCA cycle but increased the expression of most amino acid synthesis pathways such as proline, arginine, and serine, consistent with the results of physiological indicators. qRT-PCR further showed that the expression pattern was similar to the expression abundance in the transcriptome. The important metabolites and genes in celery that significantly contributed to the response to high temperatures were identified in the present study, which provided the theoretical basis for breeding heat-resistant celery. [ABSTRACT FROM AUTHOR]

• The genetic diversity of celery germplasms was evaluated based on agronomic traits, quality traits and heat tolerance. • Apigenin and cellulose were the main contributors to the variation of quality traits. • The comprehensive evaluation value of celery after heat stress had a highly significant positive correlation with the heat damage index. • The heat resistance of celery was related to its hollow/solid and color. Existing celery germplasm resources must be evaluated prior to celery biological research and application of germplasm resources. In this study, 14 agronomic and quality traits, and heat-resistance of 50 celery cultivars were analyzed. The results showed that the coefficients of variation of the 14 traits ranged from 1.73% to 64.69%, 50 samples of celery could be divided into 5 groups by cluster analysis. The primary sources of variation in agronomic traits were petiole color, hollow/solid, and yield per plant, and the primary sources of variation of quality traits were apigenin and cellulose. The photosynthetic parameters and heat damage index was investigated, and the correlation between celery germplasm resources and heat-resistance was analyzed. The result showed that heat-resistance was correlated with its hollow/solid and color. This study analyzed the genetic diversity of celery germplasm resources, screened heat-resistant and heat-sensitive varieties, and performed an association analysis with the germplasm resources, which laid the foundation for the subsequent selection of heat-resistant celery varieties. [ABSTRACT FROM AUTHOR]

There are few reports on the reproductive biology of celery, which produces small flowers in a long flowering period. Anther development was analyzed by paraffin sectioning and related genes were examined by transcriptome sequencing and qPCR. The development process was divided into nine stages based on the significant changes in the cell and tissue morphologies. These stages included: archesporial stage, sporogenous cell stage, microspore mother cell stage, dyad and tetrad stage, mononuclear microspore stage, late uninucleate microspore stage, binuclear cell stage, mature pollen stage, and dehiscence stage. A total of 1074 differentially expressed genes were identified by transcriptome sequencing in the early flower bud, middle flower bud, and early flowering period. Functional annotation indicated that these genes were involved in physiological and biochemical processes such as ribosomes metabolism, sugar metabolism, and amino acid metabolism. Transcription factors such as C2H2, AP2/ERF, bZIP, WRKY, and MYB played key regulatory roles in anther development and had different regulatory capabilities at various stages. The expression patterns based on qPCR and transcriptome data of the selected transcription factor genes showed consistency, suggesting that these genes played an important role in different flower development stages. These results provide a theoretical basis for molecular breeding of new celery varieties with pollen abortion. Furthermore, they have enriched research on the reproductive biology of celery and the Apiaceae family. [ABSTRACT FROM AUTHOR]

• AMF inoculation positively impacts Se accumulation and translocation in celery. • Low Se (≤10 mg kg−1) promotes growth, high concentrations inhibit it. • AMF enhances Se uptake, improves shoot height, root weight. • +AMF with 10 mg kg−1 Se4+ produces Se-rich celery, addressing deficiencies. Celery (Apium graveolens L.) has a strong capacity to enrich selenium (Se) and is a good system for research on Se enrichment in vegetables. Arbuscular mycorrhizal fungi (AMF) are commonly used plant symbionts that affect plant growth and their effectiveness is plant species specific. However, there is little research on the effects of AMF inoculation on the accumulation and translocation of Se in celery. The treatments in this study included inoculation with AMF (+AMF) and the application of different types and concentrations of exogenous Se. We evaluated the growth, root mycorrhizal colonization, photosynthetic pigment content, ascorbate-glutathione cycle (ASA-GSH cycle), the accumulation and translocation of Se and the combination of AMF + Se compared with an untreated control. The application of low concentrations of Se (≤10 mg kg−1) stimulated celery growth, while high concentrations (>20 mg kg−1) had the opposite effect. The inhibition of celery growth was more severe with Se6+ than Se4+ when applied at the same concentration. The accumulation of Se improved in all the organs of celery as the supply increased. AMF had a significant positive effect on the accumulation and translocation of Se. In addition, +AMF significantly increased the shoot height and root fresh weight of celery and reduced the inhibitory effect of Se on growth. However, +AMF had slight effects on the levels of photosynthetic pigments and the ASA-GSH cycle. +AMF combined with 10 mg kg−1 sodium selenite (Se4+) is an effective way to produce Se-rich celery. [ABSTRACT FROM AUTHOR]