Characteristic analysis of BZR genes family and their responses to hormone treatments and abiotic stresses in Carya illinoinensis

As the core of Brassinosteroids (BR) signaling pathway, BR-resistant (BZR) transcription factor regulates thousands of targeted genes mediating photomophogenesis, pollen sterility, cell expansion and stress response. Pecan (Carya illinoinensis) is a famous trees species of Carya, and its nut has high nutritional and economic values. However, there has no report on BZR genes family in pecan yet. Herein, totals of seven CiBZR members were identified in pecan genome, which were predicted to be hydrophilic unstable proteins and located in the nucleus. CiBZR genes had close evolutionary relationships with CcBZRs and JrBZRs in both Carya cathayensis and Juglans regia. These seven CiBZR genes were located independently on 7 chromosomes without doubling or tandem duplication. Based on the analysis of conserved motifs and gene structures, CiBZR genes were divided into three categories. More than 40 cis-acting elements were found in the 2 kb promoter regions of CiBZRs, which were mainly involved in hormone, light, and stress response, and plant growth and development. Notably, some of these CiBZR proteins were mainly located in the nucleus, had the self-activation ability and interaction relationship with BIN2 kinase, and negatively regulated the expression of CiCPD and CiDWF4. Gene expressions analysis further showed that CiBZR genes could express in many tissues and shared similar expression trends during embryo development. Moreover, most CiBZR genes responded to BR, Gibberellin (GA), Strigolactone (SL), salt, acid and osmotic stress. This study provides theoretical basis for the subsequent study on the role of CiBZR family genes in plant growth, development and stress responses.

Genome-wide identification and expression analysis of BZR gene family and associated responses to abiotic stresses in cucumber (Cucumis sativus L.)

BACKGROUND

BRASSINAZOLE-RESISTANT (BZR) is a class of specific transcription factor (TFs) involved in brassinosteroid (BR) signal transduction. The regulatory mechanism of target genes mediated by BZR has become one of the key research areas in plant BR signaling networks. However, the functions of the BZR gene family in cucumber have not been well characterized.

RESULTS

In this study, six CsBZR gene family members were identified by analyzing the conserved domain of BES1 N in the cucumber genome. The size of CsBZR proteins ranges from 311 to 698 amino acids and are mostly located in the nucleus. Phylogenetic analysis divided CsBZR genes into three subgroups. The gene structure and conserved domain showed that the BZR genes domain in the same group was conserved. Cis-acting element analysis showed that cucumber BZR genes were mainly involved in hormone response, stress response and growth regulation. The qRT-PCR results also confirmed CsBZR response to hormones and abiotic stress.

CONCLUSION

Collectively, the CsBZR gene is involved in regulating cucumber growth and development, particularly in hormone response and response to abiotic stress. These findings provide valuable information for understanding the structure and expression patterns of BZR genes.

Transcription factors DkBZR1/2 regulate cell wall degradation genes and ethylene biosynthesis genes during persimmon fruit ripening

BRASSINAZOLE RESISTANT (BZR) transcription factors are critical components of the brassinosteroid signalling pathway, but their possible roles in fruit ripening have rarely been reported. In this study, four BZR sequences were isolated from persimmon fruit. Among the four BZR genes, DkBZR1/2 were expressed in persimmon fruit; DkBZR1 protein amount decreased and dephosphorylated DkBZR2 gradually accumulated during the storage period. DkBZR1/2 proteins were localized in both the nucleus and cytoplasm and accumulated in the nucleus after 24-epibrassinolide treatment. DkBZR1 suppressed the transcription of Diospyros kaki endo-1,4-betaglucanase 1 (DkEGase1) and 1-aminocyclopropane-1-carboxylate synthase 1 (DkACS1) by binding to the BR response element (BRRE) in their promoters, and DkBZR2 activated the transcription of pectate lyase 1 (DkPL1) and 1-aminocyclopropane-1-carboxylate oxidase 2 (DkACO2) by binding to the E-box motif in their promoters. Transient overexpression of DkBZR2 promoted the conversion of acid-soluble pectin to water-soluble pectin and increased ethylene production in persimmon fruit. Our findings indicate that DkBZR1 and DkBZR2 serve as repressors and activators of persimmon fruit ripening, respectively.

Response of BpBZR genes to abiotic stress and hormone treatment in Betula platyphylla

Brassinazole-resistant (BZR) transcription factors have important roles in the brassinosteroid (BR) signalling pathway and are widely involved in plant growth and abiotic stress processes. However, there are few studies on the functions and regulatory mechanisms of BZR TFs in birch. In this study, 5 BZR genes were identified from birch. The qRT-PCR results showed that the expression levels of most BpBZRs were significantly downregulated and/or upregulated in at least one organ following NaCl and PEG stress or ABA, GA₃ and JA treatments. In particular, BpBZR1 expression was changed in all three organs after exposure to NaCl stress at all time points, indicating that this gene may be involved in salt stress. The BpBZR1 transcription factor was shown to have transcriptional activation activity in a yeast two-hybrid assay. Through a transient transformation system, we found that overexpression of BpBZR1 in birch resulted in lower H₂O₂ and MDA accumulation, higher SOD and POD activities and maintained a higher photosynthetic intensity and a lower chlorophyll degradation rate than those of the control plants under salt stress. These results preliminarily showed that overexpression of the BpBZR1 gene increased the tolerance of birch to salt stress.

Genome-wide identification, characterization, and expression patterns of the BZR transcription factor family in sugar beet (Beta vulgaris L.)

BACKGROUND

BRASSINAZOLE-RESISTANT (BZR) family genes encode plant-specific transcription factors (TFs) that participate in brassinosteroid signal transduction. BZR TFs have vital roles in plant growth, including cell elongation. However, little is known about BZR genes in sugar beet (Beta vulgaris L.).

RESULTS

Therefore, we performed a genome-wide investigation of BvBZR genes in sugar beet. Through an analysis of the BES1_N conserved domain, six BvBZR gene family members were identified in the sugar beet genome, which clustered into three subgroups according to a phylogenetic analysis. Each clade was well defined by the conserved motifs, implying that close genetic relationships could be identified among the members of each subfamily. According to chromosomal distribution mapping, 2, 1, 1, 1, and 1 genes were located on chromosomes 1, 4, 5, 6, and 8, respectively. The cis-acting elements related to taproot growth were randomly distributed in the promoter sequences of the BvBZR genes. Tissue-specific expression analyses indicated that all BvBZR genes were expressed in all three major tissue types (roots, stems, and leaves), with significantly higher expression in leaves. Subcellular localization analysis revealed that Bv1_fxre and Bv6_nyuw are localized in the nuclei, consistent with the prediction of Wolf PSORT.

CONCLUSION

These findings offer a basis to predict the functions of BZR genes in sugar beet, and lay a foundation for further research of the biological functions of BZR genes in sugar beet.

Genome-Wide Identification, Characterization, and Expression Profiling of the Legume BZR Transcription Factor Gene Family

The BRASSINAZOLE-RESISTANT (BZR) family of transcription factors (TFs) are positive regulators in the biosynthesis of brassinosteroids. The latter is a class of steroid hormones that affect a variety of developmental and physiological processes in plants. BZR TFs play essential roles in the regulation of plant growth and development, including multiple stress-resistance functions. However, the evolutionary history and individual expression patterns of the legume BZR genes has not been determined. In this study, we performed a genome-wide investigation of the BZR gene family in seven legume species. In total, 52 BZR genes were identified and characterized. By analyzing their phylogeny, we divided these BZR genes into five groups by comparison with orthologs/paralogs in Arabidopsis thaliana. The intron/exon structural patterns and conserved protein motifs of each gene were analyzed and showed high group-specificities. Legume BZR genes were unevenly distributed among their corresponding genomes. Genome and gene sequence comparisons revealed that gene expansion of the BZR TF family in legumes mainly resulted from segmental duplications and that this family has undergone purifying selection. Synteny analysis showed that BZR genes tended to localize within syntenic blocks conserved across legume genomes. The expression patterns of BZR genes among various legume vegetative tissues and in response to different abiotic stresses were analyzed using a combination of public transcriptome data and quantitative PCR. The patterns indicated that many BZR genes regulate legume organ development and differentiation, and significantly respond to drought and salt stresses. This study may provide valuable information for understanding the evolution of BZR gene structure and expression, and lays a foundation for future functional analysis of the legume BZR genes by species and by gene.