Antioxidant, Antimicrobial Activities and Characterization of Polyphenol-Enriched Extract of Egyptian Celery (Apium graveolens L., Apiaceae) Aerial Parts via UPLC/ESI/TOF-MS.

Medicinal plant extracts are increasingly considered a major source of innovative medications and healthcare products. This study focused on preparing a polyphenol enriched water extract of Egyptian celery "Apium graveolens L., Apiaceae" aerial parts (TAE) in an endeavor to accentuate its antioxidant capacity as well as its antimicrobial activity. (TAE) of celery was partitioned against different organic solvents to yield dichloromethane (DCM), ethyl acetate (EAC), and butanol (BUOH) fractions. (TAE) and the organic fractions thereof besides the remaining mother liquor (ML) were all screened for their antioxidant capacity using various protocols viz. monitoring the reducing amplitudes for ferric ions (FRAP), and radical scavenging potentials of oxygen (ORAC), 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH), and metal chelation assays. The examination procedure revealed both (TAE) extract and (DCM) fraction, to pertain the highest antioxidant potentials, where the IC50 of the (TAE) using ABTS and metal chelation assays were ca. 34.52 ± 3.25 and 246.6 ± 5.78 µg/mL, respectively. The (DCM) fraction recorded effective results using the FRAP, ORAC, and DPPH assays ca. 233.47 ± 15.14 and 1076 ± 25.73 µM Trolox equivalents/mg sample and an IC50 474.4 ± 19.8 µg/mL, respectively. Additionally, both (TAE) and (DCM) fraction exerted antimicrobial activities recording inhibition zones (mm) (13.4 ± 1.5) and (12.0 ± 1.0) against Staphylococcus aureus and (11.0 ± 1.2) and (10.0 ± 1.3) against Escherichia coli, respectively, with no anti-fungal activity. Minimum inhibitory concentration (MIC) of (TAE) and (DCM) fraction were 1250 and 2500 µg/mL, respectively. UPLC/ESI/TOF-MS unveiled the chemical profile of both (TAE) and (DCM) fraction to encompass a myriad of active polyphenolic constituents including phenylpropanoids, coumarins, apigenin, luteolin, and chrysoeriol conjugates.

Molecular mechanisms and hormonal regulation underpinning morphological dormancy: a case study using Apium graveolens (Apiaceae).

Underdeveloped (small) embryos embedded in abundant endosperm tissue, and thus having morphological dormancy (MD) or morphophysiological dormancy (MPD), are considered to be the ancestral state in seed dormancy evolution. This trait is retained in the Apiaceae family, which provides excellent model systems for investigating the underpinning mechanisms. We investigated Apium graveolens (celery) MD by combined innovative imaging and embryo growth assays with the quantification of hormone metabolism, as well as the analysis of hormone and cell-wall related gene expression. The integrated experimental results demonstrated that embryo growth occurred inside imbibed celery fruits in association with endosperm degradation, and that a critical embryo size was required for radicle emergence. The regulation of these processes depends on gene expression leading to gibberellin and indole-3-acetic acid (IAA) production by the embryo and on crosstalk between the fruit compartments. ABA degradation associated with distinct spatiotemporal patterns in ABA sensitivity control embryo growth, endosperm breakdown and radicle emergence. This complex interaction between gibberellins, IAA and ABA metabolism, and changes in the tissue-specific sensitivities to these hormones is distinct from non-MD seeds. We conclude that the embryo growth to reach the critical size and the associated endosperm breakdown inside MD fruits constitute a unique germination programme.

Expression Analysis, Functional Marker Development and Verification of AgFNSI in Celery.

Apigenin is one of the primary flavonoids in celery, which has a high medicinal value. Flavone synthase I (FNSI) is the last step enzyme in apigenin biosynthesis. In this study, the 1492 bp promoter sequence before AgFNSI initiation codon (ATG) of celery was obtained, which included methyl jasmonate (MeJA) responsive elements, light responsive elements, anaerobic induction elements and five MYB binding sites. AgFNSI was sensitive to temperature, UV-B, water deficit and MeJA. Comparative analysis of AgFNSI genome and promoter sequences among celery accessions with different apigenin content showed that there were four allelic variations in AgFNSI, and four accessions with high apigenin content belonged to AgFNSIa, and five accessions with low apigenin content belonged to AgFNSIc. Three pairs of dominant complementary markers were designed based on the single-nucleotile polymorphisms (SNPs) of the AgFNSIa and AgFNSIc genomes and promoter sequences. Three pairs of functional markers were validated by 112 celery accessions. The results showed that AFPA1/AFPB1 detected significant differences in apigenin content between different genotypes. Therefore, marker AFPA1/AFPB1 is associated with apigenin content in celery and could be used for the genetic improvement of apigenin content in celery.

Isolation, purification and characterization of an ascorbate peroxidase from celery and overexpression of the AgAPX1 gene enhanced ascorbate content and drought tolerance in Arabidopsis.

BACKGROUND: Celery is a widely cultivated vegetable abundant in ascorbate (AsA), a natural plant antioxidant capable of scavenging free radicals generated by abiotic stress in plants. Ascorbate peroxidase (APX) is a plant antioxidant enzyme that is important in the synthesis of AsA and scavenging of excess hydrogen peroxide. However, the characteristics and functions of APX in celery remain unclear to date. RESULTS: In this study, a gene encoding APX was cloned from celery and named AgAPX1. The transcription level of the AgAPX1 gene was significantly upregulated under drought stress. AgAPX1 was expressed in Escherichia coli BL21 (DE3) and purified. The predicted molecular mass of rAgAPX1 was 33.16 kDa, which was verified by SDS-PAGE assay. The optimum pH and temperature for rAgAPX1 were 7.0 and 55 °C, respectively. Transgenic Arabidopsis hosting the AgAPX1 gene showed elevated AsA content, antioxidant capacity and drought resistance. Less decrease in net photosynthetic rate, chlorophyll content, and relative water content contributed to the high survival rate of transgenic Arabidopsis lines after drought. CONCLUSIONS: The characteristics of APX in celery were different from that in other species. The enhanced drought resistance of overexpressing AgAPX1 in Arabidopsis may be achieved by increasing the accumulation of AsA, enhancing the activities of various antioxidant enzymes, and promoting stomatal closure. Our work provides new evidence to understand APX and its response mechanisms to drought stress in celery.

Genomic identification of AP2/ERF transcription factors and functional characterization of two cold resistance-related AP2/ERF genes in celery (Apium graveolens L.).

MAIN CONCLUSION: This study analyzed the AP2/ERF transcription factors in celery and showed that two dehydration-responsive-element-binding (DREB) transcription factors, AgDREB1 and AgDREB2, contribute to the enhanced resistance to abiotic stress in transgenic Arabidopsis. The AP2/ERF family is a large family of transcription factors (TFs) in higher plants that plays a central role in plant growth, development, and response to environmental stress. Here, 209 AP2/ERF family members were identified in celery based on genomic and transcriptomic data. The TFs were classified into four subfamilies (i.e., DREB, ERF, RAV, and AP2) and Soloist. Evolution analysis indicated that the AP2/ERF TFs are ancient molecules and have expanded in the long-term evolution process of plants and whole-genome duplication events. AgAP2/ERF proteins may be associated with multiple biological processes as predicted by the interaction network. The expression profiles and sequence alignment analysis of the TFs in the DREB-A1 group showed that eight genes could be divided into four branches. Two genes, AgDREB1 and AgDREB2, from the DREB-A1 group were selected for further analysis. Subcellular localization assay suggested that the two proteins are nuclear proteins. Yeast one hybrid assay demonstrated that the two proteins could bind to the dehydration-responsive element (DRE). The overexpression of AgDREB1 and AgDREB2 in Arabidopsis induced the increased tolerance to cold treatment and the up-regulation of the COR genes expression. AgDREB1 and AgDREB2 might function as transcriptional activators in regulating the downstream genes by binding to corresponding DRE to enhance stress tolerance in celery.

De novo assembly, transcriptome characterization, lignin accumulation, and anatomic characteristics: novel insights into lignin biosynthesis during celery leaf development.

Celery of the family Apiaceae is a biennial herb that is cultivated and consumed worldwide. Lignin is essential for cell wall structural integrity, stem strength, water transport, mechanical support, and plant pathogen defense. This study discussed the mechanism of lignin formation at different stages of celery development. The transcriptome profile, lignin distribution, anatomical characteristics, and expression profile of leaves at three stages were analyzed. Regulating lignin synthesis in celery growth development has a significant economic value. Celery leaves at three stages were collected, and Illumina paired-end sequencing technology was used to analyze large-scale transcriptome sequences. From Stage 1 to 3, the collenchyma and vascular bundles in the petioles and leaf blades thickened and expanded, whereas the phloem and the xylem extensively developed. Spongy and palisade mesophyll tissues further developed and were tightly arranged. Lignin accumulation increased in the petioles and the mesophyll (palisade and spongy), and the xylem showed strong lignification. Lignin accumulation in different tissues and at different stages of celery development coincides with the anatomic characteristics and transcript levels of genes involved in lignin biosynthesis. Identifying the genes that encode lignin biosynthesis-related enzymes accompanied by lignin distribution may help elucidate the regulatory mechanisms of lignin biosynthesis in celery.

Plant uptake-assisted round-the-clock photocatalysis for complete purification of aquaculture wastewater using sunlight.

A novel reactor equipped with solar batteries, Bi2O3/TiO2 film photocatalyst, and celery plant was designed and used for purification of aquaculture wastewater. The Bi2O3/TiO2 film photocatalyst started photocatalytic degradation of organonitrogen compounds under irradiation of sunlight. Meanwhile, the solar batteries absorbed and converted excess sunlight into electric energy and then started UV lamps at night, leading to round-the-clock photocatalysis. Subsequently, the inorganic nitrogen species including NH4(+), NO2(-), and NO3(-) resulting from photocatalytic degradation of the organonitrogen compounds could subsequently be uptaken by the celery plant as the fertilizer to reduce the secondary pollution. It was found that, after 24 h circulation, both organonitrogen compounds and NO2(-) species were completely removed, while NH4(+) and NO3(-) contents also decreased by 30% and 50%, respectively. The reactor could be used repetitively, showing a good potential in practical application.

Isolation and characterization of the Agvip1 gene and response to abiotic and metal ions stresses in three celery cultivars.

VIP1, a VirE2-interacting protein 1, specifically interacts with VirE2 and acts as a molecular adaptor in Agrobacterium-mediated genetic transformation. This protein is widely used in plant genetic engineering. In this study, we cloned the Agvip1 gene that encodes the AgVIP1 protein from three celery (Apium graveolens) cultivars, namely, "Liuhe Huangxinqin", "Jinnan Shiqin", and "Ventura". The sequence analysis indicated that the Agvip1 gene from the three celery cultivars contained 768 bp Open Reading Frame and encoded with 255 amino acid residues. The N-terminal of AgVIP1 contained RNA recognition motif superfamily, a conserved domain. The Agvip1 gene in three cultivars had very high homology. The phylogenetic tree of VIP1-like proteins was constructed among celery and other plant species, showing that VIP1-like proteins from Solanum lycopersicum and Solanum tuberosum in Solanaceae had the shortest evolutionary relationship with AgVIP1 from A. graveolens in Apiaceae. Quantitative real-time PCR demonstrated that the Agvip1 gene had tissue-specific expression, mainly in the celery root. The expression analysis showed that the Agvip1 gene was induced by abiotic stresses differently in three celery cultivars. In "Liuhe Huangxinqin", the Agvip1 gene was up-regulated under hot, cold stresses. In "Jinnan Shiqin", the Agvip1 gene was up-regulated obviously under cold, drought treatments. However, in "Ventura", the Agvip1 gene was up-regulated under salt stress. The Agvip1 was also induced after metal ions treatments in three celery cultivars. These findings will provide more information on the Agvip1 gene and AgVIP1 protein, and enhance the understanding of the Agvip1 gene regulatory mechanisms under abiotic and metal ions stresses in celery.

Endophytic fungi occurring in fennel, lettuce, chicory, and celery--commercial crops in southern Italy.

The occurrence of endophytic fungi in fennel, lettuce, chicory, and celery crops was investigated in southern Italy. A total of 186 symptomless plants was randomly collected and sampled at the stage of commercial ripeness. Fungal species of Acremonium, Alternaria, Fusarium, and Plectosporium were detected in all four crops; Plectosporium tabacinum was the most common in all crop species and surveyed sites. The effect of eight endophytic isolates (five belonging to Plectosporium tabacinum and three to three species of Acremonium) inoculated on lettuce plants grown in gnotobiosis was assessed by recording plant height, root length and dry weight, collar diameter, root necrosis, and leaf yellowing. P. tabacinum and three species of Acremonium, inoculated on gnotobiotically grown lettuce plants, showed pathogenic activity that varied with the fungal isolate. Lettuce plants inoculated with the isolates Ak of Acremonium kiliense, Ac of Acremonium cucurbitacearum, and P35 of P. tabacinum showed an increased root growth, compared to the non-inoculated control. The high frequency of P. tabacinum isolation recorded in lettuce plants collected in Bari and Metaponto, and in fennel plants from Foggia agricultural districts, suggests a relationship not only between a crop species and P. tabacinum, but also between the occurrence of the endophyte and the crop rotation history of the soil.

Determination and analysis of guided wave propagation using magnetic resonance elastography.

We present a novel extension of standard magnetic resonance elastography (MRE) measurement and analysis methods, which is applicable in cases where the medium is characterized by waveguides or fiber bundles (i.e., muscle) leading to constrained propagation of elastic waves. As a demonstration of this new method, MRI is utilized to identify the pathways of the individual fibers of a stalk of celery, and 3D MRE is then performed throughout the volume containing the celery fibers for a measurement of the displacements. A Helmholtz decomposition is performed permitting a separation of the displacements into longitudinal and transverse components, and an application of a hybrid Radon transform permits a spectral decomposition of wave propagation along the fibers. Dot product projections between these elastic displacements measured in the global coordinate system and three Frenet vectors representing the tangent and two corresponding orthogonal vectors along any particular fiber orientation yield the displacement contributions to wave propagation along the fiber as if it were a waveguide. A sliding window spatial Fourier transform is then performed along the length of each fiber to obtain dispersion images that portray space-wavenumber profiles. Therefore, this method can permit localized tracking and characterization of wave types, velocities, and coupling along arbitrarily oriented fibers.