Analysis of WRKY transcription factor family based on full-length transcriptome sequencing in Polygonatum cyrtonema / 中国中药杂志

WRKY transcription factor family plays an important role in plant growth and development, secondary metabolite synthesis, and biotic and abiotic stress responses. The present study performed full-length transcriptome sequencing of Polygonatum cyrtonema by virtue of the PacBio SMRT high-throughput platform, identified the WRKY family by bioinformatics methods, and analyzed the physicochemical properties, subcellular localization, phylogeny, and conserved motifs. The results showed that 30.69 Gb nucleotide bases and 89 564 transcripts were obtained after redundancy removal. These transcripts had a mean length of 2 060 bp and an N50 value of 3 156 bp. Based on the full-length transcriptome sequencing data, 64 candidate proteins were selected from the WRKY transcription factor family, with the protein size of 92-1 027 aa, the relative molecular mass of 10 377.85-115 779.48 kDa, and the isoelectric point of 4.49-9.84. These WRKY family members were mostly located in the nucleus and belonged to the hydrophobic proteins. According to the phylogenetic analysis of WRKY family in P. cyrtonema and Arabidopsis thaliana, all WRKY family members were clustered into seven subfamilies and WRKY proteins from P. cyrtonema were distributed in different numbers in these seven subgroups. Expression pattern analysis confirmed that 40 WRKY family members had distinct expression patterns in the rhizomes of 1-and 3-year-old P. cyrtonema. Except for PcWRKY39, the expression of 39 WRKY family members was down-regulated in 3-year-old samples. In conclusion, this study provides abundant reference data for genetic research on P. cyrtonema and lays a foundation for the in-depth investigation of the biological functions of the WRKY family.

The role of plant WRKY transcription factors against salt stress: a review / 生物工程学报

High salt content in soils severely hampers plant growth and crop yields. Many transcription factors in plants play important roles in responding to various stresses, but their molecular mechanisms remain unclear. WRKY transcription factors are one of the largest families of transcription factors in higher plants that are involved in and influence many aspects of plant growth and development. They play important roles in responding to salt stress. The regulation of gene expression by WRKY proteins is mainly achieved by binding to the DNA's specific cis-regulatory elements, the W-box elements (TTGACC). In recent years, there have been many studies revealing the roles and mechanisms of WRKY family members, from model plant Arabidopsis to agricultural crops. This paper reviews the latest research progress on WRKY transcription factors in response to salt stress and discusses the current challenges and future perspectives of WRKY transcription factor research.

Bioinformatics and expressional analysis of WRKY transcription factor family in Baphicacanthus cusia / 药学学报

WRKY, a class of conserved transcription factors in plants, plays important roles in plant growth, development and secondary metabolism. In the present study, 65 WRKY members were identified from de novo transcriptome sequencing data of three different tissues (root, stems and leaves) of Baphicacanthus cusia. BcWRKY proteins contained from 221 to 706 amino acids and the isoelectric point is from 4.68 to 9.68. Molecular weights range from 25 711.8 to 75 475 Da. The main secondary structures of BcWRKYs protein are random coil. A subcellular localization prediction indicated that the putative BcWRKY proteins were enriched in the nuclear region. Phylogenetic analysis showed that BcWRKYs could be categorized into three groups and five subgroups (Group IIa, Group IIb, Group IIc, Group IId and Group IIe) in Group II. Structural analysis found that all BcWRKY proteins contained a highly conserved motif WRKYGQK. Finally, the transcriptional profiles of ten BcWRKY genes highly expressed in root, stem and leaf tissues under abscisic acid (ABA), methyl jasmonate (MeJA), or salicylic acid (SA) treatment were systematically investigated using qRT-PCR analysis. Results showed that a total of ten BcWRKY genes were differentially expressed in response to ABA, MeJA, and SA treatment. This work would be provided a basis for further elucidating the molecular mechanism of WRKY transcription factors in the biosynthesis of indole alkaloids in B. cusia.

Identification and expression analysis of WRKY gene family in eukaryotic algae / 生物工程学报

WRKY is a superfamily of plant-specific transcription factors, playing a critical regulatory role in multiple biological processes such as plant growth and development, metabolism, and responses to biotic and abiotic stresses. Although WRKY genes have been characterized in a variety of higher plants, little is known about them in eukaryotic algae, which are close to higher plants in evolution. To fully characterize algal WRKY family members, we carried out multiple sequence alignment, phylogenetic analysis, and conserved domain prediction to identify the WRKY genes in the genomes of 30 algal species. A total of 24 WRKY members were identified in Chlorophyta, whereas no WRKY member was detected in Rhodophyta, Glaucophyta, or Bacillariophyta. The 24 WRKY members were classified into Ⅰ, Ⅱa, Ⅱb and R groups, with a conserved heptapeptide domain WRKYGQ(E/A/H/N)K and a zinc finger motif C-X4-5-C-X22-23-H-X-H. Haematococcus pluvialis, a high producer of natural astaxanthin, contained two WRKY members (HaeWRKY-1 and HaeWRKY-2). Furthermore, the coding sequences of HaeWRKY-1 and HaeWRKY-2 genes were cloned and then inserted into prokaryotic expression vector. The recombinant vectors were induced to express in Escherichia coli BL21(DE3) cells and the fusion proteins were purified by Ni-NTA affinity chromatography. HaeWRKY-1 had significantly higher expression level than HaeWRKY-2 in H. pluvialis cultured under normal conditions. High light stress significantly up-regulated the expression of HaeWRKY-1 while down-regulated that of HaeWRKY-2. The promoters of HaeWRKY genes contained multiple cis-elements responsive to light, ethylene, ABA, and stresses. Particularly, the promoter of HaeWRKY-2 contained no W-box specific for WRKY binding. However, the W-box was detected in the promoters of HaeWRKY-1 and the key enzyme genes HaeBKT (β-carotene ketolase) and HaePSY (phytoene synthase) responsible for astaxanthin biosynthesis. Considering these findings and the research progress in the related fields, we hypothesized that the low expression of HaeWRKY-2 under high light stress may lead to the up-regulation of HaeWRKY-1 expression. HaeWRKY-1 may then up-regulate the expression of the key genes (HaeBKT, HaePSY, etc.) for astaxanthin biosynthesis, consequently promoting astaxanthin enrichment in algal cells. The findings provide new insights into further analysis of the regulatory mechanism of astaxanthin biosynthesis and high light stress response of H. pluvialis.

Transcriptome-wide Identification and Expression Profiles of WRKY Transcription Factor in Prunella vulgaris / 中国实验方剂学杂志

Objective:To identify WRKY genes from the transcriptome dataset of Prunella vulgaris by bioinformatics method, and analyze the protein characteristics and expression level of these genes. Method:WRKY transcription factor were identified from the P. vulgaris transcriptome database，their motif，physical and chemical properties，functional annotations，family evolution and expression patterns were analyzed, and their functions were predicted. Result:A total of 23 WRKY transcription factors were identified from P. vulgaris in this study by computational prediction method.Structural analysis found that WRKY proteins contained a highly conserved motif WRKYGQK. Phylogenetic analysis of WRKYs together with the homologous genes from Arabidopsis thaliana could be divided into two groups（group Ⅰ-Ⅱ）. There were 7 members in group Ⅰ，and 16 members in group Ⅱ, group Ⅱ was subdivided into five subgroups，namely group Ⅱb （3 members），Ⅱc（5 members），Ⅱd（3 members），Ⅱe（5 members）. The physical and chemical properties of WRKY protein showed that the amino acid number was between 85 and 599，the molecular weight was between 9 527.5-66 438.45 Da，the theoretical isoelectric point was between 5.01-9.83.Among them, c13719.graph_c0，c32199.graph_c0，c24547.graph_c0，c37881.graph_c0 may play a role in the regulation of secondary metabolitessynthesis of P. vulgaris.And c32199.graph_c0，c26537.graph_c0，c23728.graph_c0 may has an effect in identifying and defensing pathogens in P. vulgaris.The transcriptional profiles of these 23 WRKY genes in various tissues were investigated using transcriptome dataset.The results showed that the expression level of WRKY genes varied significantly in different tissues. Conclusion:This study identifies the organization and transcriptional profiles of PmWRKY genes for the first time, so as to provide the helpful information for further studies of functions of WRKYs.

Cloning and expression analysis of WRKY5 gene in Dendrobium officinale / 中草药

Objective: In order to isolate and analysize the bioinformatics and expression pattern of DoWRKY5 gene from Dendrobium officinale. Methods: A WRKY gene was first obtained by transcriptome sequencing and reverse transcription-polymerase chain reaction (RT-PCR) from D. officinale and analyzed by bioinformatics tools. The tissue expression pattern and the low temperature stress, abscisic acid (ABA) stress, and sucrose stress responses were analyzed by qRT-PCR. Results: The cDNA sequence of DoWRKY5 gene was isolated, which was 1 336 bp in length, with an open reading frame (ORF) of 834 bp and an encoded polypeptide of 277 amino acid. The amino acid sequence contained a conserved WRKY domains and a zinc finger structures (C2H2), belonging to Group II of WRKY family. Expression analysis by qRT-PCR showed that DoWRKY5 was expressed in the roots, stems, and leaves of D. officinale, and the most abundant in leaves. The amount of DoWRKY5 expression were significantly increased under low temperature of 4℃ and different time. Moreover, the expression of DoWRKY5 could be induced by ABA and source. Conclusion: DoWRKY5 may be an important transcription factor to response cold stress and other abiotic stresses in D. officinale, which provides a foundation for further study of cold tolerance mechanism and cold-resistant breeding of D. officinale.