University MOOC should be added with farmer interested sections and provide individualized service to adapt to farmer training.

Vegetables represent an important agricultural industry in China. New farmers and new technologies for vegetable production have emerged in recent years, which makes farmer training very necessary. On the other hand, massive open online courses (MOOCs) are currently widely used in universities. The purpose of this study is to investigate the importance of different sections of a university MOOC focused on olericulture to farmers with different demographic characteristics and provide a basis to improve university MOOCs for farmer training. The survey results suggest that the age, education level, gender, farmer scale, facility type and profit of farmer learners are important factors determining evaluations of the importance of different MOOC sections, indicating that services customized to different farmer populations are necessary. Among different sections of MOOC "Olericulture", farmers with younger age, higher education, larger farm, more advanced facility and more profit were more interesting in sections include cultural, social and theoretical knowledge, and less interesting in practical skill sections. Based on the survey, eight new sections including one marketing subsection (new agricultural supplies and market news), one social subsection (laws and regulations), two practical subsections (practice videos, photos and videos from other farms), and three comprehensive subsections (discussion of practical issues, mechanization, and smart olericulture) were added to the original MOOC, and the results indicate that this improvement is efficient in enhancing the importance evaluations and profits of all farmer learners, especially among those with high education levels.

Morphological characteristics, anatomical structure, and dynamic change of ascorbic acid under different storage conditions of celery.

Ascorbic acid (AsA) is a crucial antioxidant in vegetables. Celery (Apium graveolens L.) is a vegetable of Apiaceae and is rich in AsA. Till now, the effects of different storage conditions on celery morphological characteristics, anatomical features, and antioxidant accumulation are unclear. Here, the celery cvs. 'Sijixiaoxiangqin' and 'Liuhehuangxinqin' were selected as experimental materials, and the two celery plants grown for 65 days were harvested from soils and stored in light at room temperature (25 °C), darkness at low temperature (4 °C), and darkness at room temperature (25 °C) for 0, 6, 24, 30, 48, and 54 h, respectively. The results showed that celery in darkness had better water retention capacity than celery in light. Morphological changes in celery mesophyll, leaf veins, and petioles were the least in darkness at low temperature (4 °C). The weight loss rate and wilting degree in darkness at low temperature (4 °C) were the lowest, and the AsA content remained at a high level. The expression patterns of GDP-D-mannose pyrophosphorylase (AgGMP) and L-galactose dehydrogenase (AgGalDH) were similar to the change of AsA content. The results indicated that low temperature and dark was the optimized storage condition for 'Sijixiaoxiangqin' and 'Liuhehuangxinqin' celery. AgGMP and AgGalDH genes may play an important role in the accumulation of AsA in celery. This paper will provide potential references for prolonging the shelf life of celery and other horticultural crops.

Differential hydroxylation efficiency of the two non-heme carotene hydroxylases: DcBCH1, rather than DcBCH2, plays a major role in carrot taproot.

Carotene hydroxylase plays an important role in catalyzing the hydroxylation of carotene to xanthopylls, including two types: non-heme carotene hydroxylase (BCH type) and heme-containing cytochrome P450 hydroxylase (P450 type). Two BCH-encoding genes were annotated in the carrot genome. However, the role of BCHs and whether there are functional interactions between the duplicated BCHs in carrot remains unclear. In this study, two BCH encoding genes, DcBCH1 and DcBCH2, were cloned from carrot. The relative expression level of DcBCH1 was much higher than that of DcBCH2 in carrot taproots with different carotene accumulation levels. Overexpression of DcBCH1 in 'KRD' (high carotene accumulated) carrot changed the taproot color from orange to yellow, accompanied by substantial reductions in α-carotene and ß-carotene. There was no obvious change in taproot color between transgenic 'KRD' carrot overexpressing DcBCH2 and control carrot. Simultaneously, the content of α-carotene in the taproot of DcBCH2-overexpressing carrot decreased, but the content of ß-carotene did not change significantly in comparison with control carrot. Using the CRISPR/Cas9 system to knock out DcBCH1 in 'KRD' carrot lightened the taproot color from orange to pink-orange; the content of α-carotene in the taproot increased slightly, while the ß-carotene content was still significantly decreased, compared with control carrot. In DcBCH1-knockout carrot, the transcript level of DcBCH2 was significantly increased. These results indicated that in carrot taproot, DcBCH1 played the main function of BCH enzyme, which could hydroxylate α-carotene and ß-carotene; DcBCH1 and DcBCH2 had functional redundancy, and these two DcBCHs could partially compensate for each other.

AgGMP encoding GDP-D-mannose pyrophosphorylase from celery enhanced the accumulation of ascorbic acid and resistance to drought stress in Arabidopsis.

Ascorbic acid (AsA) is an important nutrient in celery, the conversion of D-mannose-1-P to GDP-D-mannose catalyzed by GDP-D-mannose pyrophosphorylase (GMPase) represents the first committed step in the biosynthesis of AsA. To clarify the function of the AgGMP gene of celery, the AgGMP gene was cloned from celery cv. 'Jinnan Shiqin' . It contains an open reading frame (ORF) with the length of 1,086 bp, encoding 361 amino acids. AgGMP protein was highly conserved among different plant species. Phylogenetic analysis demonstrated that the GMP proteins from celery and carrot belonged to the same branch. AgGMP protein was mainly composed of three α-helixes and certain random coils. No signal peptide was found in the AgGMP protein. The subcellular localization indicated that the AgGMP protein was located in the cytoplasm. The relative expression levels of AgGMP in 'Jinnan Shiqin' were significantly up-regulated at 2 h and 4 h under drought stress treatments. AsA contents in transgenic Arabidopsis lines hosting AgGMP gene were higher than that in wild type plants, and the root lengths were also longer in the MS medium containing 300 mM mannitol. The present study provides useful evidence for the functional involvement of AgGMP in regulating AsA accumulation and response to drought stress in celery.

AgMYB12, a novel R2R3-MYB transcription factor, regulates apigenin biosynthesis by interacting with the AgFNS gene in celery.

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.

Origin, evolution, breeding, and omics of Apiaceae: a family of vegetables and medicinal plants.

Many of the world's most important vegetables and medicinal crops, including carrot, celery, coriander, fennel, and cumin, belong to the Apiaceae family. In this review, we summarize the complex origins of Apiaceae and the current state of research on the family, including traditional and molecular breeding practices, bioactive compounds, medicinal applications, nanotechnology, and omics research. Numerous molecular markers, regulatory factors, and functional genes have been discovered, studied, and applied to improve vegetable and medicinal crops in Apiaceae. In addition, current trends in Apiaceae application and research are also briefly described, including mining new functional genes and metabolites using omics research, identifying new genetic variants associated with important agronomic traits by population genetics analysis and GWAS, applying genetic transformation, the CRISPR-Cas9 gene editing system, and nanotechnology. This review provides a reference for basic and applied research on Apiaceae vegetable and medicinal plants.

Integrative genome, transcriptome, microRNA, and degradome analysis of water dropwort (Oenanthe javanica) in response to water stress.

Water dropwort (Liyang Baiqin, Oenanthe javanica (BI.) DC.) is an aquatic perennial plant from the Apiaceae family with abundant protein, dietary fiber, vitamins, and minerals. It usually grows in wet soils and can even grow in water. Here, whole-genome sequencing of O. javanica via HiSeq 2000 sequencing technology was reported for the first time. The genome size was 1.28 Gb, including 42,270 genes, of which 93.92% could be functionally annotated. An online database of the whole-genome sequences of water dropwort, Water dropwortDB, was established to share the results and facilitate further research on O. javanica (database homepage: http://apiaceae.njau.edu.cn/waterdropwortdb ). Water dropwortDB offers whole-genome and transcriptome sequences and a Basic Local Alignment Search Tool. Comparative analysis with other species showed that the evolutionary relationship between O. javanica and Daucus carota was the closest. Twenty-five gene families of O. javanica were found to be expanded, and some genetic factors (such as genes and miRNAs) related to phenotypic and anatomic differentiation in O. javanica under different water conditions were further investigated. Two miRNA and target gene pairs (miR408 and Oja15472, miR171 and Oja47040) were remarkably regulated by water stress. The obtained reference genome of O. javanica provides important information for future work, thus making in-depth genetic breeding and gene editing possible. The present study also provides a foundation for the understanding of the O. javanica response to water stress, including morphological, anatomical, and genetic differentiation.

AgZDS, a gene encoding ζ-carotene desaturase, increases lutein and ß-carotene contents in transgenic Arabidopsis and celery.

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 ß-carotene and up-regulated the expression levels of the genes involved in carotenoids biosynthesis. The contents of lutein and ß-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.

Overexpression of a carrot BCH gene, DcBCH1, improves tolerance to drought in Arabidopsis thaliana.

BACKGROUND: Carrot (Daucus carota L.), an important root vegetable, is very popular among consumers as its taproot is rich in various nutrients. Abiotic stresses, such as drought, salt, and low temperature, are the main factors that restrict the growth and development of carrots. Non-heme carotene hydroxylase (BCH) is a key regulatory enzyme in the ß-branch of the carotenoid biosynthesis pathway, upstream of the abscisic acid (ABA) synthesis pathway. RESULTS: In this study, we characterized a carrot BCH encoding gene, DcBCH1. The expression of DcBCH1 was induced by drought treatment. The overexpression of DcBCH1 in Arabidopsis thaliana resulted in enhanced tolerance to drought, as demonstrated by higher antioxidant capacity and lower malondialdehyde content after drought treatment. Under drought stress, the endogenous ABA level in transgenic A. thaliana was higher than that in wild-type (WT) plants. Additionally, the contents of lutein and ß-carotene in transgenic A. thaliana were lower than those in WT, whereas the expression levels of most endogenous carotenogenic genes were significantly increased after drought treatment. CONCLUSIONS: DcBCH1 can increase the antioxidant capacity and promote endogenous ABA levels of plants by regulating the synthesis rate of carotenoids, thereby regulating the drought resistance of plants. These results will help to provide potential candidate genes for plant drought tolerance breeding.

DcCCD4 catalyzes the degradation of α-carotene and ß-carotene to affect carotenoid accumulation and taproot color in carrot.

Carotenoids are important natural pigments that give bright colors to plants. The difference in the accumulation of carotenoids is one of the key factors in the formation of various colors in carrot taproots. Carotenoid cleavage dioxygenases (CCDs), including CCD and 9-cis epoxycarotenoid dioxygenase, are the main enzymes involved in the cleavage of carotenoids in plants. Seven CCD genes have been annotated from the carrot genome. In this study, through expression analysis, we found that the expression level of DcCCD4 was significantly higher in the taproot of white carrot (low carotenoid content) than orange carrot (high carotenoid content). The overexpression of DcCCD4 in orange carrots caused the taproot color to be pale yellow, and the contents of α- and ß-carotene decreased sharply. Mutant carrot with loss of DcCCD4 function exhibited yellow color (the taproot of the control carrot was white). The accumulation of ß-carotene was also detected in taproot. Functional analysis of the DcCCD4 enzyme in vitro showed that it was able to cleave α- and ß-carotene at the 9, 10 (9', 10') double bonds. In addition, the number of colored chromoplasts in the taproot cells of transgenic carrots overexpressing DcCCD4 was significantly reduced compared with that in normal orange carrots. Results showed that DcCCD4 affects the accumulation of carotenoids through cleavage of α- and ß-carotene in carrot taproot.

The Accumulation of Lutein and ß-Carotene and Transcript Profiling of Genes Related to Carotenoids Biosynthesis in Yellow Celery.

Carotenoids are the general term of natural pigments. The formation of plant color is probably related to the components of carotenoids. As the yellow variety of celery, it is rich in the composition and content of carotenoids. However, the transcript profiling and roles of the genes related to carotenoids biosynthesis in yellow celery remain unclear. In this study, three yellow celery cultivars at different growth stages were used to analyze the content and composition of carotenoids and transcriptional changes of carotenoid biosynthesis-related genes. The lutein and ß-carotene were detected in yellow celery cultivar, while α-carotene and lycopene were not detected. The contents of lutein and ß-carotene were higher in leaf blades than in petioles. During the growth and development, the contents of lutein and ß-carotene gradually decreased in celery. Compared with the other two cultivars, the contents of lutein and ß-carotene were the highest in 'Huangtaiji' of 65 days after sowing (DAS) and 85 DAS and 'Liuhehuangxinqin' of 105 DAS, respectively. The expression levels of AgLCYB and AgPSY2 genes were significantly correlated with lutein and ß-carotene contents. This work provided a reference for the further study on carotenoid metabolisms in yellow celery and also made sense on the way of cultivating yellow celery with high carotenoids content.

A celery transcriptional repressor AgERF8 negatively modulates abscisic acid and salt tolerance.

Ethylene response factors (ERFs) widely exist in plants and have been reported to be an important regulator of plant abiotic stress. Celery, a common economic vegetable of Apiaceae, contains lots of ERF transcription factors (TFs) with various functions. AP2/ERF TFs play positive or negative roles in plant growth and stress response. Here, AgERF8, a gene encoding EAR-type AP2/ERF TF, was identified. The AgERF8 mRNA accumulated in response to both abscisic acid (ABA) signaling and salt treatment. AgERF8 was proving to be a nucleus-located protein and could bind to GCC-box. The overexpression of AgERF8 in Arabidopsis repressed the transcription of downstream genes, AtBGL and AtBCH. Arabidopsis overexpressing AgERF8 gene showed inhibited root growth under ABA and NaCl treatments. AgERF8 transgenic lines showed low tolerance to ABA and salt stress than wild-type plants. Low increment in SOD and POD activities, increased accumulation of MDA, and significantly decreased plant fresh weights and chlorophyll levels were detected in AgERF8 hosting lines after treated with ABA and NaCl. Furthermore, the overexpression of AgERF8 also inhibited the levels of ascorbic acid and antioxidant-related genes (AtCAT1, AtSOD1, AtPOD, AtSOS1, AtAPX1, and AtP5CS1) expression in transgenic Arabidopsis. This finding indicated that AgERF8 negatively affected the resistance of transgenic Arabidopsis to ABA and salt stress through regulating downstream genes expression and relevant physiological changes. It will provide a potential sight to further understand the functions of ERF TFs in celery.

The gene encoding lycopene epsilon cyclase of celery enhanced lutein and ß-carotene contents and confers increased salt tolerance in Arabidopsis.

Celery (Apium graveolens L.) is a leafy vegetable of Apiaceae, which is greatly popular because of its rich nutrients. Lutein and ß-carotene are two important carotenoids. Lycopene epsilon cyclase (LCY-ε) is a key branch point enzyme in the carotenoid biosynthetic pathway. In this study, we cloned the AgLCY-ε gene from celery and overexpressed it in Arabidopsis. The results showed that both lutein and ß-carotene accumulation increased significantly in transgenic Arabidopsis hosting AgLCY-ε gene, compared with wild type (WT) plants. The transcription levels of AtPSY and AtCRTISO genes involved in carotenoids biosynthesis also increased in transgenic lines. One-month-old transgenic Arabidopsis seedlings were treated with 200 mM NaCl. The malondialdehyde (MDA) content in transgenic Arabidopsis plants after salt treatment was significantly lower, and the activities of the two antioxidant enzymes, superoxide dismutase (SOD) and peroxidase (POD), were significantly increased than that of WT plants. Overexpression of AgLCY-ε gene showed increased lutein and ß-carotene accumulations, and enhanced salt tolerance in transgenic plants.

AgNAC1, a celery transcription factor, related to regulation on lignin biosynthesis and salt tolerance.

The NAC transcription factor participates in various biotic and abiotic stress responses and plays a critical role in plant development. Lignin is a water-insoluble dietary fiber, but it is second only to cellulose in abundance. Celery is the main source of dietary fiber, but its quality and production are limited by various abiotic stresses. Here, AgNAC1 containing the NAM domain was identified from celery. AgNAC1 was found to be a nuclear protein. Transgenic Arabidopsis thaliana plants hosting AgNAC1 have longer root lengths and stomatal axis lengths than the wide type (WT). The evidence from lignin determination and expression levels of lignin-related genes indicated that AgNAC1 plays a vital role in lignin biosynthesis. Furthermore, the results of the physiological characterization and the drought and salt treatments indicate that AgNAC1-overexpressing plants are significantly resistive to salt stress. Under drought and salt treatments, the AgNAC1 transgenic Arabidopsis thaliana plants presented increased superoxide dismutase (SOD) and peroxidase (POD) activities and decreased malondialdehyde (MDA) content and size of stomatal apertures relatively to the WT plants. The AgNAC1 served as a positive regulator in inducing the expression of stress-responsive genes. Overall, the overexpressing AgNAC1 enhanced the plants' resistance to salt stress and played a regulatory role in lignin accumulation.

A novel plant protein-disulfide isomerase participates in resistance response against the TYLCV in tomato.

MAIN CONCLUSION: Overexpression or silencing of the SlPDI could increase plants resistance or sensitivity to TYLCV through enhancing or reducing the plant's antioxidant capacity. Tomato yellow leaf curl virus (TYLCV), a plant virus that could infect a variety of crops, is particularly destructive to tomato growth. Protein disulfide isomerase (PDI) is a member of the thioredoxin (Trx) superfamily, is capable of catalyzing the formation and heterogeneity of protein disulfide bonds and inhibiting the aggregation of misfolded proteins. Studies have shown that PDI plays important roles in plant response to abiotic stress, there is no research report on the function of PDI in response to biotic stress, especially TYLCV infection. Here, we identified a tomato PDI gene, SlPDI, was involved in regulating tomato plants resistance to TYLCV. Subcellular localization results showed that SlPDI was located at the endoplasmic reticulum (ER), and its location remained unchanged after infection with TYLCV virus. Overexpression or silencing of SlPDI could increase plants resistance or sensitivity to TYLCV. Transgenic plants that overexpressing SlPDI exhibit enhanced antioxidant activity evidenced by lower hydrogen peroxide (H2O2) level and higher activity of superoxide dismutase (SOD) and peroxidase (POD) in comparison with WT plants, after infected by TYLCV. Moreover, the SlPDI-silencing plants showed opposite results. The promoter analyzes result showed that SlPDI was involved in response to salicylic acid (SA), and our experimental results also showed that the expression level of SlPDI was induced by SA. Taken together, our results indicated that SlPDI could regulate plant resistance to TYLCV through enhancing the protein folding function of ER and promoting the synthesis and conformation of antioxidant-related proteins.

The ascorbate peroxidase 1 regulates ascorbic acid metabolism in fresh-cut leaves of tea plant during postharvest storage under light/dark conditions.

Postharvest storage conditions affect the ascorbic acid (AsA) levels in fresh-cut leaves of horticultural crops. However, the detailed mechanism of AsA metabolism in the fresh-cut leaves of tea plant (Camellia sinensis) during postharvest storage under light/dark conditions remains unclear. To investigate the AsA mechanism, we treated fresh-cut tea leaves with light/dark during postharvest storage. An ascorbate peroxidase 1 (CsAPX1) protein involved in AsA metabolism was identified by iTRAQ analysis. Gene expression profile of CsAPX1 encoding ascorbate peroxidase (APX) was regulated by light/dark conditions. AsA accumulation and APX activity were suppressed by light/dark conditions. SDS-PAGE analysis showed that the molecular mass of recombinant CsAPX1 protein was about 34.45 kDa. Subcellular localization indicated that CsAPX1 protein was a cytosol ascorbate peroxidase. Overexpression CsAPX1 in Arabidopsis indicated that the decrease of AsA content and APX activity in transgenic lines were less significant than that of WT during postharvest storage under light/dark conditions. These data suggested that CsAPX1 involved in regulating AsA metabolism through effecting on the changes of AsA accumulation and APX activity in fresh-cut tea leaves during postharvest storage under light/dark conditions.

Advances in AP2/ERF super-family transcription factors in plant.

In the whole life process, many factors including external and internal factors affect plant growth and development. The morphogenesis, growth, and development of plants are controlled by genetic elements and are influenced by environmental stress. Transcription factors contain one or more specific DNA-binding domains, which are essential in the whole life cycle of higher plants. The AP2/ERF (APETALA2/ethylene-responsive element binding factors) transcription factors are a large group of factors that are mainly found in plants. The transcription factors of this family serve as important regulators in many biological and physiological processes, such as plant morphogenesis, responsive mechanisms to various stresses, hormone signal transduction, and metabolite regulation. In this review, we summarized the advances in identification, classification, function, regulatory mechanisms, and the evolution of AP2/ERF transcription factors in plants. AP2/ERF family factors are mainly classified into four major subfamilies: DREB (Dehydration Responsive Element-Binding), ERF (Ethylene-Responsive-Element-Binding protein), AP2 (APETALA2) and RAV (Related to ABI3/VP), and Soloists (few unclassified factors). The review summarized the reports about multiple regulatory functions of AP2/ERF transcription factors in plants. In addition to growth regulation and stress responses, the regulatory functions of AP2/ERF in plant metabolite biosynthesis have been described. We also discussed the roles of AP2/ERF transcription factors in different phytohormone-mediated signaling pathways in plants. Genomic-wide analysis indicated that AP2/ERF transcription factors were highly conserved during plant evolution. Some public databases containing the information of AP2/ERF have been introduced. The studies of AP2/ERF factors will provide important bases for plant regulatory mechanisms and molecular breeding.

Integrative transcriptome, proteome, and microRNA analysis reveals the effects of nitrogen sufficiency and deficiency conditions on theanine metabolism in the tea plant (Camellia sinensis).

Nitrogen (N) is associated with amino acid metabolism in higher plants. Theanine is an important amino acid in tea plants. To explore the relationship between theanine metabolism and N conditions, we examined the differentially expressed genes (DEGs), proteins (DEPs), and microRNAs (DEMs) involved in theanine metabolism in tea plant shoots and roots under N sufficiency and deficiency conditions. Transcriptome, proteome, and microRNA analyses were performed on tea plant shoots and roots under N sufficiency and deficiency conditions. The contents of theanine, expression levels of genes involved in theanine metabolism, contents of proteinogenic amino acids, and activity of enzymes were analyzed. The DEP-DEG correlation pairs and negative DEM-DEG interactions related to theanine metabolism were identified based on correlation analyses. The expression profiles of DEGs and negative DEM-DEG pairs related to theanine biosynthesis were consistent with the sequencing results. Our results suggest that the molecular and physiological mechanism of theanine accumulation is significantly affected by N sufficiency and deficiency conditions. The DEGs, DEPs, and DEMs and the activity of the enzymes involved in theanine biosynthesis might play vital roles in theanine accumulation under N sufficiency and deficiency conditions in the shoots and roots of tea plants.

NAC Family Transcription Factors in Carrot: Genomic and Transcriptomic Analysis and Responses to Abiotic Stresses.

Carrot is an annual or biennial herbaceous plant of the Apiaceae family. Carrot is an important vegetable, and its fresh taproot, which contains rich nutrients, is the main edible part. In the life cycle of carrot, NAC family transcription factors (TFs) are involved in almost all physiological processes. The function of NAC TFs in carrot remains unclear. In this study, 73 NAC family TF members in carrot were identified and characterized using transcriptome and genome databases. These members were divided into 14 subfamilies. Multiple sequence alignment was performed, and the conserved domains, common motifs, phylogenetic tree, and interaction network of DcNAC proteins were predicted and analyzed. Results showed that the same group of NAC proteins of carrot had high similarity. Eight DcNAC genes were selected to detect their expression profiles under abiotic stress treatments. The expression levels of the selected DcNAC genes significantly increased under treatments with low temperature, high temperature, drought, and salt stress. Results provide potentially useful information for further analysis of the roles of DcNAC transcription factors in carrot.