Genes In Chinese Cabbage Research Articles

Identification and Functional Exploration of BraGASA Genes Reveal Their Potential Roles in Drought Stress Tolerance and Sexual Reproduction in Brassica rapa L. ssp. pekinensis.

Gibberellic acid-stimulated Arabidopsis sequences (GASAs) are a subset of the gibberellin (GA)-regulated gene family and play crucial roles in various physiological processes. However, the GASA genes in Brassica rapa have not yet been documented. In this study, we identified and characterized 16 GASA genes in Chinese cabbage (Brassica rapa L. ssp. pekinensis). Analysis of the conserved motifs revealed significant conservation within the activation segment of BraGASA genes. This gene family contains numerous promoter elements associated with abiotic stress tolerance, including those for abscisic acid (ABA) and methyl jasmonate (MeJA). Expression profiling revealed the presence of these genes in various tissues, including roots, stems, leaves, flowers, siliques, and callus tissues. When plants were exposed to drought stress, the expression of BraGASA3 decreased notably in drought-sensitive genotypes compared to their wild-type counterparts, highlighting the potentially crucial role of BraGASA3 in drought stress. Additionally, BraGASAs exhibited various functions in sexual reproduction dynamics. The findings contribute to the understanding of the function of BraGASAs and provide valuable insights for further exploration of the GASA gene function of the BraGASA gene in Chinese cabbage.

BrWax1 function in wax biosynthesis was verified by allelic mutations in Chinese cabbage

The primary function of cuticular wax is to prevent non-stomatal water loss, while the wax deficiency conferring a glossy appearance on plants is conductive to crop commodity qualities. We previously mapped a wax-deficient gene BrWax1 in a natural mutant ‘08A235-2’ by SSR marker, and predicted Bra013809 (BrWax1) as the candidate gene in Chinese cabbage (Brassica rapa L. ssp. pekinensis). In order to verifying the function of BrWax1, two allelic wax-crystal deficiency mutants wdm4 and wdm8 from an EMS mutagenesis population of Chinese cabbage were screened. wdm4 was applied to identify the mutant gene, with the finding that BraA01g015290.3C, the homologous of AT4G24510 (AtCER2), was the candidate gene. Bra013809 in Brara_Chiifu_V1.5 and BraA01g015290.3C in Brara_Chiifu_V3.0 were annotated as the same gene in Brassicaceae Database. A SNP (C to T) on BrWax1 in wdm4 resulted in a stopgain, and a SNP (G to A) on BrWax1 in wdm8 led to the deletion of 38 bases which caused a stopgain at the 190th amino acid. These results finally verified the function of BrWax1 in the wax biosynthesis. Our findings emphasize the crucial role of the BrWax1 gene in cuticular wax biosynthesis in Chinese cabbage and suggest its potential as a valuable genetic resource for breeding for glossy appearance.

Functional analysis of the key BrSWEET genes for sugar transport involved in the Brassica rapa-Plasmodiophora brassicae interaction

Plasmodiophora brassicae, the causative agent of clubroot disease, establishes a long-lasting parasitic relationship with its host by inducing the expression of sugar transporters. Previous studies have indicated that most BrSWEET genes in Chinese cabbage are up-regulated upon infection with P. brassicae. However, the key BrSWEET genes responsive to P. brassicae have not been definitively identified. In this study, we selected five BrSWEET genes and conducted a functional analysis of them. These five BrSWEET genes showed a notable up-regulation in roots after P. brassicae inoculation. Furthermore, these BrSWEET proteins were localized to the plasma membrane. Yeast functional complementation assays confirmed transport activity for glucose, fructose, or sucrose in four BrSWEETs, with the exception of BrSWEET2a. Mutants and silenced plants of BrSWEET1a, -11a, and -12a showed lower clubroot disease severity compared to wild-type plants, while gain-of-function Arabidopsis thaliana plants overexpressing these three BrSWEET genes exhibited significantly higher disease incidence and severity. Our findings suggested that BrSWEET1a, BrSWEET11a, and BrSWEET12a play pivotal roles in P. brassicae-induced gall formation, shedding light on the role of sugar transporters in host-pathogen interactions.

Mapping-Based Localization of Blackleg-Resistant Candidate Genes of Chinese Cabbage (Brassica rapa).

Recently, blackleg disease has seriously impacted the cultivation and development of Brassica crops. In this study, we conducted mapping-based localization of blackleg-resistant candidate genes in Chinese cabbage. Through phenotype evaluation, Chinese cabbage materials 15S414 and 15S420 were selected as blackleg-resistant and blackleg-susceptible parents, respectively. Inheritance pattern analysis suggested that the dominant major genes mainly determined the blackleg resistance of Chinese cabbage. Upon bulked segregant analysis, the blackleg-resistant candidate genes were initially located within a 4.3-Mb interval on chromosome A06. Through construction of the genetic linkage map, blackleg-resistant candidate genes were further limited to a region of 160 kb containing seven resistance-related genes. Coding sequence variation analysis revealed that all seven resistance-related genes displayed various degrees of single nucleotide polymorphism variations between the parent materials 15S414 and 15S420.

Genome-Wide Identification, Expression Analysis and Functional Study of DELLA Genes in Chinese Cabbage (Brassica rapa L. ssp. pekinensis).

DELLA protein is a crucial factor which played pivotal roles in regulating numerous intriguing biological processes in plant development and abiotic stress responses. However, little is known about the function and information of DELLA protein in Chinese cabbage. Using 5 DELLA gene sequences in Arabidopsis Thaliana as probes, 5 DELLA genes in Chinese cabbage were identified by Blast search in Chinese cabbage database (Brassica database (BRAD)). The National Center for Biotechnology Information (NCBI), ExPaSy, SWISS-MODEL, DNAMAN, MEGA 11, PlantCARE were used to identify and analyze the DELLA gene family of Chinese cabbage. Gene expression was analyzed by quantitative real-time polymerase chain reaction (qRT-PCR). The function of BraA10gRGL3 was verified by overexpression and phenotypic analysis of BraA10gRGL3 and yeast hybrid. In this study, 5 BraDELLAs homologous to Arabidopsis thaliana were identified and cloned based on the Brassica database, namely, BraA02gRGL1, BraA05gRGL2, BraA10gRGL3, BraA06gRGA and BraA09gRGA. All BraDELLAs contain the DELLA, TVHYNP, and GRAS conserved domains. Cis-element analysis revealed that the promoter regions of these 5 DELLA genes all contain light-responsive elements, TCT motif, I-box, G-box, and box 4, which are associated with GA signaling. Transcriptome analysis results proved that the expression of BraA02gRGL1, BraA05gRGL2, and BraA10gRGL3 in Y2 at different growth stages were lower than them in Y7, which is consistent with the phenotype that Y7 exhibited stronger stress tolerance than Y2. It is worth emphasizing that even through the overexpression of BraA10gRGL3-Y7 in Arabidopsis resulted in smaller leaf size and lower fresh weight compared to the wild type (WT) Arabidopsis: Columbia, a stronger response to abiotic stresses was observed in BraA10gRGL3-Y7. It indicated that BraA10gRGL3-Y7 can improve the stress resistance of plants by inhibiting their growth. Moreover, the yeast two-hybrid experiment confirmed that BraA10gRGL3-Y7 can interacted with BraA05gGID1a-Y7, BraA04gGID1b1, BraA09gGID1b3-Y2, and BraA06gGID1c, whereas BraA10gRGL3-Y2 cannot interact with any BraGID1. Collectively, BraDELLAs play important role in plant development and response to abiotic stress. The differences in amino acid sequences between BraA10gRGL3-Y2 and BraA10gRGL3-Y7 may result in variations in their protein binding sites, thus affecting their interaction with the BraGID1 family proteins. This systematic analysis lays the foundation for further study of the functional characteristics of DELLA genes of Chinese cabbage.

Efficient transformation of the isolated microspores of Chinese cabbage (Brassica rapa L. ssp. pekinensis) by particle bombardment

BackgroundThe low efficiency of genetic transformation in Chinese cabbage (Brassica rapa L. ssp. pekinensis) is the key problem affecting functional verification. Particle bombardment is a widely used method along with the Agrobacterium-mediated method. As a physical means, it has almost no restrictions on the type of host and a wide range of receptor types, which largely avoids the restriction of explants. The bombardment parameters, which include the number of bombardments, the bombardment pressure, and the bombardment distance, may affect the microspores' genetic transformation efficiency.ResultsThe transformation efficiency was improved using the particle bombardment method under the combination of bombardment shot times (3, 4, 5) × bombardment pressure (900, 1100, 1350 psi) × bombardment distance (3, 6, 9 cm). The average viability of microspores in the treatment group ranged from 74.76 to 88.55%, while the control group was 88.09%. When the number of shot times was 4, the number of embryos incubated in the treatment group ranged from 16 to 236 per dish, and the control group had 117 embryos per dish. When the bombardment parameters of the biolistic method were 4 shot times—1350 psi—3 cm, 4 times—1100 psi—3 cm, and 4 times—900 psi—3 cm, they had high transient expression efficiency, and the average number of transformed microspores was 21.67, 11.67, and 11.67 per dish (3.5 mL), respectively. When the bombardment parameters were 4 times, 900 psi, and 6 cm, the highest genetically transformed embryos were obtained, and the transformation efficiency reached 10.82%.ConclusionA new genetic transformation system with proper parameters for Chinese cabbage microspores was established using particle bombardment. This proper transformation system could provide a useful tool for the improvement of cultivar quality and the investigation of functional genes in Chinese cabbage.

Genome-Wide Identification of BrassinaZole Resistant (BZR) Gene Family in Brassica rapa ssp. pekinensis and Its Expression Pattern During Flowering Process

The BrassinaZole Resistant (BZR) gene family mediates the signal transduction of brassinolide, which is vital in regulating vegetative and reproductive growth of plants. In this research, a comprehensive analysis of all candidate BrBZR genes in Chinese cabbage (Brassica rapa ssp. pekinensis) was conducted using bioinformatics methods, including protein physicochemical properties, evolutionary relationship, gene structure, and conserved domains. Additionally, these candidate genes’ expression patterns during flowering development were analyzed utilizing transcriptome data, and key genes that regulate flowering of Chinese cabbage were screened. In the results, 14 BrBZR genes were identified, with coding sequence (CDS) lengths of 460–1162 bp, and encoding proteins of 152–386 amino acids. The majority of BrBZRs had a highly conserved motif 1 as well as numerous regulatory elements associated with hormone and abiotic stress responses. Transcriptome sequencing showed that 12 BrBZRs were expressed during the flowering development, among which BrBES1.1 and BrBES1.2 were highly expressed, with FPKM ranges of 61.78–99.91 and 43.71–76.69, respectively. Their expression was upregulated during vernalization and flower bud differentiation, suggesting that they may play a key role in regulating the flowering process of Chinese cabbage. Overall, our study provides comprehensive insights into the BrBZR gene family, and has important implications for the further elucidation of the mechanisms that regulate flower development in Chinese cabbage and potentially other related Brassica species.

Genome-Wide Identification of the NRT1 Family Members and Their Expression under Low-Nitrate Conditions in Chinese Cabbage (Brassica rapa L. ssp. pekinensis).

Nitrate transporters (NRTs) actively take up and transform nitrate (N) to form a large family with many members and distinct functions in plant growth and development. However, few studies have identified them in the context of low nitrate concentrations in Chinese cabbage (Brassica rapa L. ssp. Pekinensis), an important vegetable in China. This study focuses on the identification and analysis of the nitrate transporter 1 (NRT1) gene family as well as various aspects, including its phylogenic distribution, chromosomal position, gene structure, conserved motifs, and duplication pattern. Using bioinformatics methods, we identified and analyzed 84 BrNRT1 genes distributed on ten chromosomes. Furthermore, we conducted an analysis of the expression profile of the NRT1 gene in various tissues of Chinese cabbage exposed to varying nitrate concentrations. A phylogenetic analysis revealed that BrNRT1s members are distributed in six distinct groups. Based on an analysis of gene structure and conserved motifs, it can be inferred that BrNRT1 exhibits a generally conserved structural pattern. The promoters of BrNRT1 were discovered to contain moosefs (MFS) elements, suggesting their potential role in the regulation of NO3- transport across the cell membrane in Chinese cabbage. A transcriptome study and a subsequent RT-qPCR analysis revealed that the expression patterns of some BrNRT1 genes were distinct to specific tissues. This observation implies these genes may contribute to nitrate uptake and transport in various tissues or organs. The results offer fundamental insights into investigating the NRT1 gene family in Chinese cabbage. These results provide basic information for future research on the functional characterization of NRT1 genes in Chinese cabbage and the elucidation of the molecular mechanisms underlying low nitrogen tolerance in Chinese cabbage.

Genome-wide identification and expression analysis of the GASA gene family in Chinese cabbage (Brassica rapa L. ssp. pekinensis)

BackgroundThe Gibberellic Acid-Stimulated Arabidopsis (GASA) gene family is widely involved in the regulation of plant growth, development, and stress response. However, information on the GASA gene family has not been reported in Chinese cabbage (Brassica rapa L. ssp. pekinensis).ResultsHere, we conducted genome-wide identification and analysis of the GASA genes in Chinese cabbage. In total, 15 GASA genes were identified in the Chinese cabbage genome, and the physicochemical property, subcellular location, and tertiary structure of the corresponding GASA proteins were elucidated. Phylogenetic analysis, conserved motif, and gene structure showed that the GASA proteins were divided into three well-conserved subfamilies. Synteny analysis proposed that the expansion of the GASA genes was influenced mainly by whole-genome duplication (WGD) and transposed duplication (TRD) and that duplication gene pairs were under negative selection. Cis-acting elements of the GASA promoters were involved in plant development, hormonal and stress responses. Expression profile analysis showed that the GASA genes were widely expressed in different tissues of Chinese cabbage, but their expression patterns appeared to diverse. The qRT-PCR analysis of nine GASA genes confirmed that they responded to salt stress, heat stress, and hormonal triggers.ConclusionsOverall, this study provides a theoretical basis for further exploring the important role of the GASA gene family in the functional genome of Chinese cabbage.

Identification and characterization of the gene BraANS.A03 associated with purple leaf color in pak choi (Brassica rapa L. ssp. chinensis).

BraANS.A3 was the key gene controlling purple leaf color in pak choi, and two short fragments of promoter region in green pak choi might be interfering its normal expression. Pak choi (B. rapa L. ssp. chinensis) is an influential and important vegetable with green, yellow, or purple leaves that is cultivated worldwide. The purple leaves are rich in anthocyanins, but the underlying genetics and evolution have yet to be extensively studied. Free-hand sections of the purple leaves indicated that anthocyanins mainly accumulate throughout the adaxial and abaxial epidermal leaf cells. Segregation analyses of an F2 population of a B. rapa ssp. chinensis L. purple leaf mutant ZBC indicated that the purple trait is controlled by an incompletely dominant nuclear gene. Bulked segregant analysis (BSA) showed that the key genes controlling the trait were between 24.25 and 38.10Mb on chromosome A03 of B. rapa. From the annotated genes, only BraA03g050560.3C, homologous to Arabidopsis AtANS, was related to the anthocyanin synthesis pathway. Genome annotation results and transcriptional sequencing analyses revealed that the BraANS.A3 gene was involved in the purple leaf trait. qRT-PCR analyses showed that BraANS.A3 was highly upregulated in ZBC but hardly expressed in the leaves of an inbred homozygous line of B. campestris ssp. chinensis L. green leaf mutant WTC, indicating that BraANS.A3 played a key role catalyzing anthocyanin synthesis in ZBC. Full-length sequence alignment of BraANS.A3 in WTC and ZBC showed that it was highly conserved in the gene region, with significant variation in the promoter region. In particular, the insertion of two short fragments of the promoter region in WTC may interfere with its normal expression. The promoter regions of ANS in six Brassica species all had multiple cis-elements involved in responses to abscisic acid, light, and stress, suggesting that ANS may be involved in multiple metabolic pathways or biological processes. Protein-protein interactions predicted that BraANS.A3 interacts with virtually all catalytic proteins in the anthocyanin synthesis pathway and has a strong relationship with Transparent Testa 8 (TT8). These results suggest that BraANS.A3 promotes anthocyanin accumulation in purple pak choi and provide new insights into the functional analysis of anthocyanin-related genes in Chinese cabbage and transcriptional regulatory networks.

Analysis of the role of BrRPP1 gene in Chinese cabbage infected by Plasmodiophora brassicae.

The clubroot disease caused by Plasmodiophora brassicae (P. brassicae) poses a serious threat to the economic value of cruciferous crops, which is a serious problem to be solved worldwide. Some resistance genes to clubroot disease in Brassica rapa L. ssp pekinensis cause by P. brassicae have been located on different chromosomes. Among them, Rcr1 and Rcr2 were mapped to the common candidate gene Bra019410, but its resistance mechanism is not clear yet. In this experiment, the differences of BrRPP1 between the resistant and susceptible material of Chinese cabbage were analyzed by gene cloning and qRT-PCR. The gene function was verified by Arabidopsis homologous mutants. The expression site of BrRPP1 gene in cells was analyzed by subcellular localization. Finally, the candidate interaction protein of BrRPP1 was screened by yeast two-hybrid library. The results showed that the cDNA sequence, upstream promoter sequence and expression level of BrRPP1 were quite different between the resistant and susceptible material. The resistance investigation found that the Arabidopsis mutant rpp1 was more susceptible to clubroot disease than the wild type, which suggested that the deletion of rpp1 reduces resistance of plant to clubroot disease. Subcellular location analysis confirmed that BrRPP1 was located in the nucleus. The interaction proteins of BrRPP1 screened from cDNA Yeast Library by yeast two-hybrid are mainly related to photosynthesis, cell wall modification, jasmonic acid signal transduction and programmed cell death. BrRPP1 gene contains TIR-NBS-LRR domain and belongs to R gene. The cDNA and promoter sequence of BrRPP1 in resistant varieties was different from that in susceptible varieties led to the significant difference of the gene expression of BrRPP1 between the resistant varieties and the susceptible varieties. The high expression of BrRPP1 gene in resistant varieties enhanced the resistance of Chinese cabbage to P. brassicae, and the interaction proteins of BrRPP1 are mainly related to photosynthesis, cell wall modification, jasmonic acid signal transduction and programmed cell death. These results provide important clues for understanding the mechanism of BrRPP1 in the resistance of B. rapa to P. brassicae.

Identification of a Leafy Head Formation Related Gene in Chinese Cabbage (Brassica rapa L. ssp. pekinensis)

Leafy head formation is one of the most important characteristics of Chinese cabbage, and the process is regulated by a series of genes and environmental factors. In this study, a non-heading short leaf mutant slm was identified from an ethyl methane sulfonate mutagenesis (EMS) population of the heading Chinese cabbage line FT. The most significant phenotypic characteristics of slm was shortening leaves and increasing leaf numbers, which led to failure to form a leafy head. Genetic analysis showed that a single recessive gene Brslm was responsible for the mutant phenotype. Mutmap analysis suggested that Brslm was located on chromosome A07, and four candidate genes were predicted. KASP analysis demonstrated that BraA07g039390.3C was the target gene of the candidates. BraA07g039390.3C is a homologous to Arabidopsis CLV1 encoding receptor kinase with an extracellular leucine-rich domain. Sequencing analysis revealed that a single SNP from G to A occurred in 904th nucleotide of Brclv1, which resulted in the change of the 302nd amino acid from Asp to Asn. The SNP was co-segregated with the mutant phenotype in F2 individuals and located on the conserved domains. These results indicated that BrCLV1 was the mutant gene for slm which led to shortening leaves and increasing leaf numbers, disrupting the leafy heading formation in FT. These findings contribute to revealing the BrCLV1 function in leafy head formation in Chinese cabbage.

Insight into the effect of low temperature treatment on trichome density and related differentially expressed genes in Chinese cabbage.

Trichome is important for help plant resist adversity and external damage. However, it often affects the appearance and taste of vegetables. In the present study, the trichome density of leaves from two Chinese cabbage cultivars with and without trichomes treated at low temperature are analyzed by biological microscope, and the differentially expressed genes related to trichomes formation were screened through transcriptome sequencing. The results showed that the number of leaves trichomes was reduced by 34.7% at low temperature compared with room temperature. A total of 661 differentially expression genes effecting trichomes formation were identified at the CT vs C, LCT vs LC, CT vs LCT. Several differentially expression genes from every comparison group were enriched in plant hormone signal transduction and amino acid biosynthesis pathway. Combined with the central genes obtained by WGCNA analysis, five candidate genes Bra029778, Bra026393, Bra030270, Bra037264 and Bra009655 were screened. qRT-PCR analysis verified that the gene expression differences were in line with the trend of transcriptome data. This study not only found possible new key genes and laid a foundation for revealing the molecular mechanism regulating the formation of trichome in Chinese cabbage, but also provided a new way to study plant surface trichomes.

HSP70 Gene Family in Brassica rapa: Genome-Wide Identification, Characterization, and Expression Patterns in Response to Heat and Cold Stress.

Heat shock proteins protect plants from abiotic stress, such as salt, drought, heat, and cold stress. HSP70 is one of the major members of the heat shock protein family. To explore the mechanism of HSP70 in Brassica rapa, we identified 28 putative HSP70 gene family members using state-of-the-art bioinformatics-based tools and methods. Based on chromosomal mapping, HSP70 genes were the most differentially distributed on chromosome A03 and the least distributed on chromosome A05. Ka/Ks analysis revealed that B. rapa evolution was subjected to intense purifying selection of the HSP70 gene family. RNA-sequencing data and expression profiling showed that heat and cold stress induced HSP70 genes. The qRT-PCR results verified that the HSP70 genes in Chinese cabbage (Brassica rapa ssp. pekinensis) are stress-inducible under both cold and heat stress. The upregulated expression pattern of these genes indicated the potential of HSP70 to mitigate environmental stress. These findings further explain the molecular mechanism underlying the responses of HSP70 to heat and cold stress.

Screening and Functional Verification of Vernalization-Related Genes in Chinese Cabbage

Flowering is very important for leaf head formation and breeding. Investigating the key genes related to vernalization process can reveal the flowering regulation mechanism and guide production and germplasm breeding. In this study, two Chinese cabbage (Brassica rapa subsp. pekinensis) inbred lines ‘1#’ and ‘2#’ with different winterness were used to identify vernalization-related genes. After low-temperature treatment, the transcriptomes of the shoot apex of the two lines were analyzed. The Arabidopsis thaliana homologues of 2,932 common differentially expressed genes with the same change trend after vernalization of two inbred lines were analysed based on Gene Ontology annotation and description. The results showed that, three genes were identified that may be related to the vernalization: Bra031210, Bra009126 and Bra033615. In which Bra031210 and Bra009126 were cloned, named BrGRP7.1 and BrCPD1, with open reading frames lengths of 507 and 1443 bp, encoding 168 and 480 amino acids, respectively. Through the expression patterns analysis, the expression of BrGRP7.1 showed a trend of initial decreasing (dipping at stage 1) and then increasing (peaking at stage 5) during flower bud differentiation of both inbred lines. Incontrast, BrCPD1 showed a first decreasing, then increasing, and last decreasing trend during flower bud differentiation of both lines. These two genes were transferred into wild-type A. thaliana. The flowering time of T2 generation of BrGRP7.1- and BrCPD1-transgenic plants was 2.31~5.11 days and 2.64~4.35 days earlier than the wild-type, respectively. In conclusion, this study screened three genes that involved in the vernalization process. Through functional verification, BrGRP7.1 and BrCPD1 were proved to have the ability to promote flowering time. This study provided a reference for further study on the flowering mechanism of Chinese cabbage.

Development of molecular markers based on CRa gene sequencing of different clubroot disease-resistant cultivars of Chinese cabbage.

CRa is a key gene in Chinese cabbage (Brassica rapa ssp. pekinensis) that confers resistance to Plasmodiophora brassicae. In order to efficiently screen the clubroot resistance (CR) gene CRa in breeding, two functional codominant markers of the CRa gene were developed. In this study, through comparing the CRa allele sequences in resistant and susceptible cultivars of Chinese cabbage, we found two insertion and deletion of sequence variations in the fourth exon between resistant and susceptible cultivars. Two functional codominant markers for CRa gene were obtained based on the variations, namely, CRaEX04-1 and CRaEX04-3. The lengths of the extended fragment of CRaEX04-1 marker were 321bp and 186bp in resistant and susceptible cultivars, respectively. In contrast, those of CRaEX04-3 were 704bp and 413bp, respectively. We verified the genetic stability between the developed markers and CRa gene using 57 Chinese cabbage cultivars with known resistance and two genetic populations. The results showed that the marker identification was completely consistent with the known phenotypes in 57 cultivars. The marker identification results followed the 3:1 of Mendel's first law in the F2 population, and the 1:1 of Mendel's first law in the BC1. CRaEX04-1 and CRaEX04-3 can be used as a practical molecular marker for breeding and germplasm resource creation of clubroot disease-resistant Chinese cabbage.

Triplication is the main evolutionary driving force of NLP transcription factor family in Chinese cabbage and related species

The NODULE-INCEPTION-like protein (NLP) is a plant-specific transcription factor (TF) family that plays an important role in both signal transduction and nitrate assimilation. However, the NLP gene family in Chinese cabbage (Brassica rapa) has yet to be studied. Here we identified 17, 16, and 32 NLP genes in Chinese cabbage, Brassica oleracea, and Brassica napus, respectively. We found that duplication of those NLP genes almost always originated from genome-wide duplication events. Further analysis (using Arabidopsis as a reference) revealed that the NLP family in Chinese cabbage and B. oleracea was characterized by direct expansion caused by whole-genome duplication. By contrast, indirect expansion characterized B. napus, which arose from hybridization and fusion of the two species. In addition, phylogenetic and homology analyses showed that the Brassica NLP gene family has been highly conserved in evolution. Finally, we also identified optimal codons for four studied species. Altogether, through comparative genome analysis methods, we presented compelling evidence that triplication is the main driving force for the NLP TF family's evolution in Chinese cabbage and related Brassica plants, a process evidently highly conserved. This work will help in better understanding the impact of genome-wide duplication on gene families of plants.

Genome-Wide Identification and Analysis of CC-NBS-LRR Family in Response to Downy Mildew and Black Rot in Chinese Cabbage.

The nucleotide-binding site–leucine-rich repeat (NBS–LRR) gene family is the largest group of plant disease resistance (R) genes widespread in response to viruses, bacteria, and fungi usually involved in effector triggered immunity (ETI). Forty members of the Chinese cabbage CC type NBS–LRR family were investigated in this study. Gene and protein characteristics, such as distributed locations on chromosomes and gene structures, were explored through comprehensive analysis. CC–NBS–LRR proteins were classified according to their conserved domains, and the phylogenetic relationships of CC–NBS–LRR proteins in Brassica rapa, Arabidopsis thaliana, and Oryza sativa were compared. Moreover, the roles of BrCC–NBS–LRR genes involved in pathogenesis-related defense were studied and analyzed. First, the expression profiles of BrCC–NBS–LRR genes were detected by inoculating with downy mildew and black rot pathogens. Second, sensitive and resistant Chinese cabbage inbred lines were screened by downy mildew and black rot. Finally, the differential expression levels of BrCC–NBS–LRR genes were monitored at 0, 1, 3, 6, 12 and 24 h for short and 0, 3, 5, 7, 10 and 14 days for long inoculation time. Our study provides information on BrCC–NBS–LRR genes for the investigation of the functions and mechanisms of CC-NBS-LRR genes in Chinese cabbage.

Gene co-expression network analysis reveals key pathways and hub genes in Chinese cabbage (Brassica rapa L.) during vernalization

BackgroundVernalization is a type of low temperature stress used to promote rapid bolting and flowering in plants. Although rapid bolting and flowering promote the reproduction of Chinese cabbages (Brassica rapa L. ssp. pekinensis), this process causes their commercial value to decline. Clarifying the mechanisms of vernalization is essential for its further application. We performed RNA sequencing of gradient-vernalization in order to explore the reasons for the different bolting process of two Chinese cabbage accessions during vernalization.ResultsThere was considerable variation in gene expression between different-bolting Chinese cabbage accessions during vernalization. Comparative transcriptome analysis and weighted gene co-expression network analysis (WGCNA) were performed for different-bolting Chinese cabbage during different vernalization periods. The biological function analysis and hub gene annotation of highly relevant modules revealed that shoot system morphogenesis and polysaccharide and sugar metabolism caused early-bolting ‘XBJ’ to bolt and flower faster; chitin, ABA and ethylene-activated signaling pathways were enriched in late-bolting ‘JWW’; and leaf senescence and carbohydrate metabolism enrichment were found in the two Chinese cabbage-related modules, indicating that these pathways may be related to bolting and flowering. The high connectivity of hub genes regulated vernalization, including MTHFR2, CPRD49, AAP8, endoglucanase 10, BXLs, GATLs, and WRKYs. Additionally, five genes related to flower development, BBX32 (binds to the FT promoter), SUS1 (increases FT expression), TSF (the closest homologue of FT), PAO and NAC029 (plays a role in leaf senescence), were expressed in the two Chinese cabbage accessions.ConclusionThe present work provides a comprehensive overview of vernalization-related gene networks in two different-bolting Chinese cabbages during vernalization. In addition, the candidate pathways and hub genes related to vernalization identified here will serve as a reference for breeders in the regulation of Chinese cabbage production.

Comparative analysis of long noncoding RNAs in angiosperms and characterization of long noncoding RNAs in response to heat stress in Chinese cabbage

Long noncoding RNAs (lncRNAs) are widely present in different species and play critical roles in response to abiotic stresses. However, the functions of lncRNAs in Chinese cabbage under heat stress remain unknown. Here, we first conducted a global comparative analysis of 247,242 lncRNAs among 37 species. The results indicated that lncRNAs were poorly conserved among different species, and only 960 lncRNAs were homologous to 524 miRNA precursors. We then carried out lncRNA sequencing for a genome-wide analysis of lncRNAs and their target genes in Chinese cabbage at different stages of heat treatment. In total, 18,253 lncRNAs were identified, of which 1229 differentially expressed (DE) lncRNAs were characterized as being heat-responsive. The ceRNA network revealed that 38 lncRNAs, 16 miRNAs, and 167 mRNAs were involved in the heat response in Chinese cabbage. Combined analysis of the cis- and trans-regulated genes indicated that the targets of DE lncRNAs were significantly enriched in the “protein processing in endoplasmic reticulum” and “plant hormone signal transduction” pathways. Furthermore, the majority of HSP and PYL genes involved in these two pathways exhibited similar expression patterns and responded to heat stress rapidly. Based on the networks of DE lncRNA-mRNAs, 29 and 22 lncRNAs were found to interact with HSP and PYL genes, respectively. Finally, the expression of several critical lncRNAs and their targets was verified by qRT-PCR. Overall, we conducted a comparative analysis of lncRNAs among 37 species and performed a comprehensive analysis of lncRNAs in Chinese cabbage. Our findings expand the knowledge of lncRNAs involved in the heat stress response in Chinese cabbage, and the identified lncRNAs provide an abundance of resources for future comparative and functional studies.