The bZIP transcription factors in Liriodendron chinense: Genome-wide recognition, characteristics and cold stress response

Genome-wide identification, expression analysis, and functional study of the bZIP transcription factor family and its response to hormone treatments in pea (Pisum sativum L.)

BACKGROUND

Basic leucine zipper (bZIP) protein is a plant-specific transcription factor involved in various biological processes, including light signaling, seed maturation, flower development, cell elongation, seed accumulation protein, and abiotic and biological stress responses. However, little is known about the pea bZIP family.

RESULTS

In this study, we identified 87 bZIP genes in pea, named PsbZIP1 ~ PsbZIP87, via homology analysis using Arabidopsis. The genes were divided into 12 subfamilies and distributed unevenly in 7 pea chromosomes. PsbZIPs in the same subfamily contained similar intron/exon organization and motif composition. 1 tandem repeat event and 12 segmental duplication events regulated the expansion of the PsbZIP gene family. To better understand the evolution of the PsbZIP gene family, we conducted collinearity analysis using Arabidopsis thaliana, Oryza sativa Japonica, Fagopyrum tataricum, Solanum lycopersicum, Vitis vinifera, and Brachypodium distachyon as the related species of pea. In addition, interactions between PsbZIP proteins and promoters containing hormone- and stress-responsive cis-acting elements suggest that the regulation of PsbZIP expression was complex. We also evaluated the expression patterns of bZIP genes in different tissues and at different fruit development stages, all while subjecting them to five hormonal treatments.

CONCLUSION

These results provide a deeper understanding of PsbZIP gene family evolution and resources for the molecular breeding of pea. The findings suggested that PsbZIP genes, specifically PSbZIP49, play key roles in the development of peas and their response to various hormones.

Genome-Wide Identification of bZIP Transcription Factors in Faba Bean Based on Transcriptome Analysis and Investigation of Their Function in Drought Response

Faba bean is an important cool-season edible legume crop that is constantly threatened by abiotic stresses such as drought. The basic leucine zipper (bZIP) gene family is one of the most abundant and diverse families of transcription factors in plants. It regulates plant growth and development and plays an important role in the response to biotic and abiotic stresses. In this study, we identified 18 members of the faba bean bZIP transcription factor family at the genome-wide level based on previous faba bean drought stress transcriptome sequencing data. A phylogenetic tree was constructed to group the 18 VfbZIP proteins into eight clades. Analysis of cis-acting elements in the promoter region suggested that these 18 VfbZIPs may be involved in regulating abiotic stress responses such as drought. Transcriptome data showed high expression of seven genes (VfbZIP1, VfbZIP2, VfbZIP5, VfbZIP7, VfbZIP15, VfbZIP17, and VfbZIP18) in the drought-tolerant cultivar under drought stress, in which VfbZIP1, VfbZIP2, and VfbZIP5 were consistently expressed as detected by quantitative real-time polymerase chain reaction (qRT-PCR) compared to the transcriptome data. Ectopic overexpression of the three VfbZIPs in tobacco, based on the potato Virus X (PVX) vector, revealed that VfbZIP5 enhanced the drought tolerance. Overexpressed VfbZIP5 in plants showed lower levels of proline (PRO), malondialdehyde (MDA), and peroxidase (POD) compared to those overexpressing an empty vector under 10 days of drought stress. Protein-protein interaction (PPI) analysis showed that VfbZIP5 interacted with seven proteins in faba bean, including VfbZIP7 and VfbZIP10. The results depict the importance of VfbZIPs in response to drought stress, and they would be useful for the improvement of drought tolerance.

Systematic Characterization of GATA Transcription Factors in Liriodendron chinense and Functional Validation in Abiotic Stresses

The Liriodendron chinense in the Magnoliaceae family is an endangered tree species useful for its socio-economic and ecological benefits. Abiotic stresses (cold, heat, and drought stress), among other factors, affect its growth, development, and distribution. However, GATA transcription factors (TFs) respond to various abiotic stresses and play a significant role in plant acclimatization to abiotic stresses. To determine the function of GATA TFs in L. chinense, we investigated the GATA genes in the genome of L. chinense. In this study, a total of 18 GATA genes were identified, which were randomly distributed on 12 of the total 17 chromosomes. These GATA genes clustered together in four separate groups based on their phylogenetic relationships, gene structures, and domain conservation arrangements. Detailed interspecies phylogenetic analyses of the GATA gene family demonstrated a conservation of the GATAs and a probable diversification that prompted gene diversification in plant species. In addition, the LcGATA gene family was shown to be evolutionarily closer to that of O. sativa, giving an insight into the possible LcGATA gene functions. Investigations of LcGATA gene duplication showed four gene duplicate pairs by the segmental duplication event, and these genes were a result of strong purified selection. Analysis of the cis-regulatory elements demonstrated a significant representation of the abiotic stress elements in the promoter regions of the LcGATA genes. Additional gene expressions through transcriptome and qPCR analyses revealed a significant upregulation of LcGATA17, and LcGATA18 in various stresses, including heat, cold, and drought stress in all time points analyzed. We concluded that the LcGATA genes play a pivotal role in regulating abiotic stress in L. chinense. In summary, our results provide new insights into understanding of the LcGATA gene family and their regulatory functions during abiotic stresses.

Genomic Survey of Heat Shock Proteins in Liriodendron chinense Provides Insight into Evolution, Characterization, and Functional Diversities

Heat shock proteins (HSPs) are conserved molecular chaperones whose main role is to facilitate the regulation of plant growth and stress responses. The HSP gene family has been characterized in most plants and elucidated as generally stress-induced, essential for their cytoprotective roles in cells. However, the HSP gene family has not yet been analyzed in the Liriodendron chinense genome. In current study, 60 HSP genes were identified in the L. chinense genome, including 7 LchiHSP90s, 23 LchiHSP70s, and 30 LchiHSP20s. We investigated the phylogenetic relationships, gene structure and arrangement, gene duplication events, cis-acting elements, 3D-protein structures, protein-protein interaction networks, and temperature stress responses in the identified L. chinense HSP genes. The results of the comparative phylogenetic analysis of HSP families in 32 plant species showed that LchiHSPs are closely related to the Cinnamomum kanehirae HSP gene family. Duplication events analysis showed seven segmental and six tandem duplication events that occurred in the LchiHSP gene family, which we speculated to have played an important role in the LchiHSP gene expansion and evolution. Furthermore, the Ka/Ks analysis indicated that these genes underwent a purifying selection. Analysis in the promoter region evidenced that the promoter region LchiHSPs carry many stress-responsive and hormone-related cis-elements. Investigations in the gene expression patterns of the LchiHSPs using transcriptome data and the qRT-PCR technique indicated that most LchiHSPs were responsive to cold and heat stress. In total, our results provide new insights into understanding the LchiHSP gene family function and their regulatory mechanisms in response to abiotic stresses.

Genomic survey of TCP transcription factors in plants: Phylogenomics, evolution and their biology

The TEOSINTE BRANCHED1 (TBI1), CYCLOIDEA (CYC), and PROLIFERATING CELL NUCLEAR ANTIGEN FACTORS (PCF1 and PCF2) proteins truncated as TCP transcription factors carry conserved basic-helix-loop-helix (bHLH) structure, related to DNA binding functions. Evolutionary history of the TCP genes has shown their presence in early land plants. In this paper, we performed a comparative discussion on the current knowledge of the TCP Transcription Factors in lower and higher plants: their evolutionary history based on the phylogenetics of 849 TCP proteins from 37 plant species, duplication events, and biochemical roles in some of the plants species. Phylogenetics investigations confirmed the classification of TCP TFs into Class I (the PCF1/2), and Class II (the C- clade) factors; the Class II factors were further divided into the CIN- and CYC/TB1- subclade. A trace in the evolution of the TCP Factors revealed an absence of the CYC/TB1subclade in lower plants, and an independent evolution of the CYC/TB1subclade in both eudicot and monocot species. 54% of the total duplication events analyzed were biased towards the dispersed duplication, and we concluded that dispersed duplication events contributed to the expansion of the TCP gene family. Analysis in the TCP factors functional roles confirmed their involvement in various biochemical processes which mainly included promoting cell proliferation in leaves in Class I TCPs, and cell division during plant development in Class II TCP Factors. Apart from growth and development, the TCP Factors were also shown to regulate hormonal and stress response pathways. Although this paper does not exhaust the present knowledge of the TCP Transcription Factors, it provides a base for further exploration of the gene family.