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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]

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]

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]

[Objectives] AgHSFB2 of celery (Apium graveolens L.) belongs to HSF gene family, which plays key roles in protecting plants from heat stress. Studying the related genes and proteins of the HSF family is important to exploring the heat resistant mechanism of celery. [ Methods ] AgHSFB2 gene was isolated from three celery cultivars, 4 Liuhehuangxinqin' 'Jinnanshiqin' and 'Ventura', respectively. Sequence analysis and quantitative real-time PCR were used to detect the expression profdes under different temperature treatments(4,38 and 42 °C ). [Results]Sequence analysis indicated that the ORF length of AgHSFB2 was 918 bp,encoding 305 amino acids. The predicted molecular weight of AgHSFB2 was 34 048 and pi value was 5.09. Phylogenetic analysis between AgHSFB2 of celery and HSF family factors in Arabidopsis showed that AgHSFB2 was close to HSFB2a and HSFB2b in the HSFB2 subgroup. Phylogenetic analysis among differnt plants illuminated that the HSFB2 of celery was close to Solarium tuberosum and Solarium lycopersicum from Solanaceae. Structure analysis implied that AgHSFB2 was composed of 3 a helixes and 4 p sheets. Quantitative real-time PCR analysis demonstrated that AgHSFB2 was tissue-specific and cultivars-specific. AgHSFB2 was mainly expressed in leaves of the three celery cultivars. Under different temperature treatments (4,38 and 42 °C ) , the expression profiles of AgHSFB2 had similar response trend, but the response time and intensity of AgHSFB2 had significant differences. AgHSFB2 of 'Ventura' was greatly upregulated after 2 h in 4 °C and 38 °C treatments. AgHSFB2 in 'Jinnanshiqin' and 'Ventura' both were upregulated obviously after 1 h in 42 °C treatment. [ Conclusions] The excessive expression of heat shock proteins can be induced by the overexpression of AgHSFB2 gene, helping the plants resist damages from the high temperature stress. [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]

• 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]