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Key message: Overexpression of AgMYB12 in celery improved the accumulation of apigenin by interacting with the AgFNS gene. Celery is a common vegetable, and its essential characteristic is medicine food homology. A natural flavonoid and a major pharmacological component in celery, apigenin plays an important role in human health. In this study, we isolated a novel R2R3-MYB transcription factor that regulates apigenin accumulation from the celery cultivar 'Jinnan Shiqin' through yeast one-hybrid screening and designated it as AgMYB12. The AgMYB12 protein was located in the nucleus. It showed transcriptional activation activity and bound specifically to the promoter of AgFNS, a gene involved in apigenin biosynthesis. Phylogenetic tree analysis demonstrated that AgMYB12 belongs to the flavonoid branch. It contains two flavonoid-related motifs, SG7 and SG7-2, and shared a highly conserved R2R3 domain with flavonoid-related MYBs. The homologous overexpression of AgMYB12 induced the up-regulation of AgFNS gene expression and accumulation of apigenin and luteolin in celery. Additionally, the expression levels of apigenin biosynthesis-related genes, including AgPAL, AgCHI, AgCHS, Ag4CL, and AgC4H, increased in transgenic celery plants. These results indicated that AgMYB12 acted as a positive regulator of apigenin biosynthesis and activated the expression of AgFNS gene. The current study provides new information about the regulation mechanism of apigenin metabolism in celery and offers a strategy for cultivating the plants with high apigenin content. [ABSTRACT FROM AUTHOR]

Gibberellins (GAs) are a group of plant hormones that play important roles in various processes. Previous studies demonstrated that GA can increase the cellulose content and lignification of plant tissues. However, the effects of altered GA levels on carrot root development have not been fully characterized. In this study, carrot roots were treated with exogenous GA3, after which thickened cell walls were detected in the xylem area. Transcriptome sequencing data revealed the changes induced by GA3. A total of 5416 differentially expressed genes (DEGs) were identified, of which 3011 and 2405 were up- and down-regulated, respectively. The DEGs were enriched in metabolic pathways, with 236 DEGs related to the cell wall. Digital gene expression data and the verification by qRT-PCR indicated that exogenous GA can alter the expression of genes involved in cell wall synthesis, suggesting a potential role for GA in cell wall organization and modification. The results of this study provide novel insights into the GA functions influencing carrot root development. [ABSTRACT FROM AUTHOR]

Increasing the level of AsA and maintaining proper lignin content will improve the quality of celery (Apium graveolens L.). However, the study on the regulation mechanism of genes related to AsA and lignin metabolism in celery was limited, especially in yellow celery. In this study, the accumulation of AsA and lignin and the expression profiles of related-genes were detected in three kinds of yellow celery. The results showed that the content of AsA was higher in the leaf blades of 'Huangtaiji' and the petioles of 'Jinhuangqincai'. The content of lignin was the highest in 'Jinhuangqincai' leaves, followed by 'Liuhehuangxinqin' and 'Huangtaiji'. The expression levels of AgAO (r = −0.032) and AgDHAR1 (r = −0.193) genes involved in AsA recycling and degradation showed negatively correlated with AsA content. AgCCoAOMT (r = 0.692) and AgF5 H (r = 0.733) genes expression were positively correlated with lignin content, while the expression of AgCAD (r = −0.694) and AgC3ʹH (r = −0.722) genes were negatively correlated with lignin content. Our current work provided potential theoretical basis for effectively changing accumulation of AsA and lignin by genetic engineering in celery. [ABSTRACT FROM AUTHOR]

Ascorbate is an antioxidant in plants. Its content is an important index to evaluate the nutritional quality of celery. In higher plant, ascorbate accumulation is effected by CO2 concentration. To study the effects of elevated CO2 (1000 µmol mol−1) on ascorbate accumulation in celery, ascorbate contents and the transcript levels of genes related to ascorbate metabolism in the leaves (leaf blade and petiole) were detected. The results of current study showed that the ascorbate and total ascorbate levels increased during all the treated stages in celery petioles, and they were 1.09–3.91 fold of the control. In leaf blades, the ascorbate contents exhibited a lower level (96.12% and 90.46% of the control) in treatments at 2 and 4 days, and then increased to 1.04 and 1.27 fold of the control in treatments at 6 and 8 days, respectively. Elevated CO2 altered the expression profiles of ascorbate-related genes and the activities of corresponding enzymes. Expression levels of the genes, AgPGI2, AgGMP, AgPMI, AgGalDH, AgGalLDH, GalUR, AgDHAR1, AgAPX1, and AgAO, in the leaf blades corresponded well to the change in ascorbate contents. At 6 days of treatment, the relative expression levels of AgPGI2, AgPMI, AgGGP1, AgGGP2, AgGalUR, AgMDHAR, AgDHAR1, and AgAPX1 in leaf blades increased, and were 4.41, 2.39, 4.65, 3.64, 3.11, 4.53, 4.59, and 3.86 times higher than that of the control. Increased ascorbate accumulation in celery leaves under elevated CO2 treatments might be also related to the change in SOD, POD, and CAT activities, as well as GSH content. These results will enhance our understanding on the effects of elevated CO2 on ascorbate accumulation and potential molecular mechanism regulating ascorbate metabolism in celery. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO 2 ) is an important regulator of plant growth and development, and its proportion in the atmosphere continues to rise now. Lignin is one of the major secondary products in plants with vital biological functions. However, the relationship between CO 2 level and xylogenesis in celery is still unknown. In order to investigate the effects of increasing CO 2 concentration on lignin accumulation in celery, ‘Jinnanshiqin’ were exposed to two CO 2 applications, 400 (e 0 ) and 1000 μmol mol −1 (e 1 ), respectively. Plant morphology and lignin distribution in celery plants treated with elevated CO 2 did not change significantly. There was an upward trend on lignin content in celery leaves, and the transcript abundance of 12 genes involved in lignin metabolism has altered in response to elevated CO 2 . The effects of high level of CO 2 on different tissues were different. Our works confirmed that CO 2 may play an important role in lignin accumulation in celery leaves. The current study will offer new evidence to understand the regulation mechanism of lignin biosynthesis under elevated CO 2 and provide a reference to improve celery quality by adjusting the growth environment. [ABSTRACT FROM AUTHOR]

• Several transgenic A. thaliana and celery lines harboring AgZDS gene were obtained. • The roles of AgZDS gene in carotenoids biosyntheisis were verified. • Overexpression of AgZDS increased the accumulation of lutein and β-carotene. • Antioxidant ability and photosynthetic ability of transgenic plants were improved. ζ-Carotene desaturase (ZDS) is one of the key enzymes regulating carotenoids biosynthesis and accumulation. Celery transgenic efficiency is low and it is difficult to obtain transgenic plants. The study on ZDS was limited in celery. Here, the AgZDS gene was cloned from celery and overexpressed in Arabidopsis thaliana and celery to verify its function. The AgZDS has typical characteristic of ZDS protein and is highly conserved in higher plants. Phylogenetic analysis showed that AgZDS has the closest evolutionary relationship with ZDSs from Solanum lycopersicum , Capsicum annuum and Tagetes erecta. Overexpression of AgZDS gene in A. thaliana and celery resulted in increased accumulations of lutein and β-carotene and up-regulated the expression levels of the genes involved in carotenoids biosynthesis. The contents of lutein and β-carotene in two lines, AtL1 and AgL5, were the highest in transgenic A. thaliana and celery, respectively. The relative expression levels of 5 genes (AtPDS , AtZISO , AtZEP , AtNCED3 , and AtCCD4) were up-regulated compared to the wild type plants. The relative expression levels of most genes in carotenoids biosynthesis pathway, such as AgPDS , AgCRTISO1 , and AgZISO , were up-regulated in transgenic celery plants. The antioxidant capacity of A. thaliana and photosynthetic capacity of celery were also enhanced. This research is the first report on the function of structure gene related to carotenoid biosynthesis in transgenic celery plants. The findings in this study demonstrated the roles of AgZDS in regulating carotenoids metabolism of celery, which laid a potential foundation for quality improvement of celery. [ABSTRACT FROM AUTHOR]