Genome-Wide In Silico Identification and Comparative Analysis of Dof Gene Family in Brassica napus

Identification and functional analysis of the DOF gene family in Populus simonii: implications for development and stress response

Background

Populus simonii, a notable native tree species in northern China, demonstrates impressive resistance to stress, broad adaptability, and exceptional hybridization potential. DOF family is a class of specific transcription factors that only exist in plants, widely participating in plant growth and development, and also playing an important role in abiotic stress response. To date, there have been no reported studies on the DOF gene family in P. simonii, and the expression levels of this gene family in different tissues of poplar, as well as its expression patterns under cold, heat, and other stress conditions, remain unclear.

Methods

In this study, DOF gene family were identified from the P. simonii genome, and various bioinformatics data on the DOF gene family, gene structure, gene distribution, promoters and regulatory networks were analyzed. Quantitative real time PCR technology was used to verify the expression patterns of the DOF gene family in different poplar tissues.

Results

This research initially pinpointed 41 PSDOF genes in P. simonii genome. The chromosomal localization results revealed that the PSDOF genes is unevenly distributed among 19 chromosomes, with the highest number of genes located on chromosomes 4, 5, and 11. A phylogenetic tree was constructed based on the homology between Arabidopsis thaliana and P. simonii, dividing the 41 PSDOF genes into seven subgroups. The expression patterns of PSDOF genes indicated that specific genes are consistently upregulated in various tissues and under different stress conditions, suggesting their pivotal involvement in both plant development and response to stress. Notably, PSDOF35 and PSDOF28 serve as pivotal hubs in the interaction network, playing a unique role in coordinating with other genes within the family.

Conclusion

The analysis enhances our comprehension of the functions of the DOF gene family in tissue development and stress responses within P. simonii. These findings provide a foundation for future exploration into the biological roles of DOF gene family.

Studying Salt-Induced Shifts in Gene Expression Patterns of Glucosinolate Transporters and Glucosinolate Accumulation in Two Contrasting Brassica Species

Brassica crops are well known for the accumulation of glucosinolates-secondary metabolites crucial for plants' adaptation to various stresses. Glucosinolates also functioning as defence compounds pose challenges to food quality due to their goitrogenic properties. Their disruption leaves plants susceptible to insect pests and diseases. Hence, a targeted reduction in seed glucosinolate content is of paramount importance to increase food acceptance. GLUCOSINOLATE TRANSPORTERS (GTRs) present a promising avenue for selectively reducing glucosinolate concentrations in seeds while preserving biosynthesis elsewhere. In this study, 54 putative GTR protein sequences found in Brassica were retrieved, employing Arabidopsis GTR1 and GTR2 templates. Comprehensive bioinformatics analyses, encompassing gene structure organization, domain analysis, motif assessments, promoter analysis, and cis-regulatory elements, affirmed the existence of transporter domains and stress-related regulatory elements. Phylogenetic analysis revealed patterns of conservation and divergence across species. Glucosinolates have been shown to increase under stress conditions, indicating a potential role in stress response. To elucidate the role of GTRs in glucosinolate transportation under NaCl stress in two distinct Brassica species, B. juncea and B. napus, plants were subjected to 0, 100, or 200 mM NaCl. Based on the literature, key GTR genes were chosen and their expression across various plant parts was assessed. Both species displayed divergent trends in their biochemical profiles as well as glucosinolate contents under elevated salt stress conditions. Statistical modelling identified significant contributors to glucosinolate variations, guiding the development of targeted breeding strategies for low-glucosinolate varieties. Notably, GTR2A2 exhibited pronounced expressions in stems, contributing approximately 52% to glucosinolate content variance, while GTR2B1/C2 displayed significant expression in flowers. Additionally, GTR2A1 and GTR1A2/B1 demonstrated noteworthy expression in roots. This study enhances our understanding of glucosinolate regulation under stress conditions, offering avenues to improve Brassica crop quality and resilience.

Comprehensive in silico analysis of the underutilized crop tef (Eragrostis tef (Zucc.) Trotter) genome reveals drought tolerance signatures

BACKGROUND

Tef (Eragrostis tef) is a C4 plant known for its tiny, nutritious, and gluten-free grains. It contains higher levels of protein, vitamins, and essential minerals like calcium (Ca), iron (Fe), copper (Cu), and zinc (Zn) than common cereals. Tef is cultivated in diverse ecological zones under diverse climatic conditions. Studies have shown that tef has great diversity in withstanding environmental challenges such as drought. Drought is a major abiotic stress severely affecting crop productivity and becoming a bottleneck to global food security. Here, we used in silico-based functional genomic analysis to identify drought-responsive genes in tef and validated their expression using quantitative RT-PCR.

RESULTS

We identified about 729 drought-responsive genes so far reported in six crop plants, including rice, wheat, maize, barley, sorghum, pearl millet, and the model plant Arabidopsis, and reported 20 genes having high-level of GO terms related to drought, and significantly enriched in several biological and molecular function categories. These genes were found to play diverse roles, including water and fluid transport, resistance to high salt, cold, and drought stress, abscisic acid (ABA) signaling, de novo DNA methylation, and transcriptional regulation in tef and other crops. Our analysis revealed substantial differences in the conserved domains of some tef genes from well-studied rice orthologs. We further analyzed the expression of sixteen tef orthologs using quantitative RT-PCR in response to PEG-induced osmotic stress.

CONCLUSIONS

The findings showed differential regulation of some drought-responsive genes in shoots, roots, or both tissues. Hence, the genes identified in this study may be promising candidates for trait improvement in crops via transgenic or gene-editing technologies.

Characterization of Dof Transcription Factors and the Heat-Tolerant Function of PeDof-11 in Passion Fruit (Passiflora edulis)

Abiotic stress is the focus of passion fruit research since it harms the industry, in which high temperature is an important influencing factor. Dof transcription factors (TFs) act as essential regulators in stress conditions. TFs can protect against abiotic stress via a variety of biological processes. There is yet to be published a systematic study of the Dof (PeDof) family of passion fruit. This study discovered 13 PeDof family members by using high-quality genomes, and the members of this characterization were identified by bioinformatics. Transcriptome sequencing and qRT-PCR were used to analyze the induced expression of PeDofs under high-temperature stress during three periods, in which PeDof-11 was significantly induced with high expression. PeDof-11 was then chosen and converted into yeast, tobacco, and Arabidopsis, with the findings demonstrating that PeDof-11 could significantly respond to high-temperature stress. This research lays the groundwork for a better understanding of PeDof gene regulation under high-temperature stress.

Identification of the inducible activity in the promoter of the soybean BBI-DII gene exposed to abiotic stress or abscisic acid

The expression of the soybean Bowman-Birk proteinase isoinhibitor DII (BBI-DII) gene and the inducible activity of its promoter were studied under salt, drought, low temperature, and abscisic acid (ABA) exposure conditions. The BBI-DII gene was induced by salt, drought, low temperature, and ABA, and the relative expression levels were 103.09-, 107.01-, 17.25- and 27.24-fold, respectively, compared with the untreated control. The putative promoter, designated BP1 (- 1255 to + 872 bp), located 5'-upstream of the BBI-DII gene was cloned. The expression of the GUS gene in pCAM-BP1 transgenic tobacco plants was highest at 5 h after treatment with salt, drought, low temperature and ABA, especially under salt and drought. Using histochemical staining and fluorescence analysis of GUS, BP1 activity under salt and drought conditions after 5 h was 1.03 and 1.07-fold, respectively, compared with that of the CaMV35S promoter. Based on a 5' deletion analysis, the segment (+ 41 to + 474 bp) was the basal region that responded to salt and drought, whereas the segment (- 820 to + 41 bp) was the area that responded to increased salt and drought activity. The BP2 (- 820 to + 872) activities were 0.98- and 1.02-fold compared with that of BP1 under salt and drought conditions and was 435 bp shorter than BP1. The salt- and drought-inducible activities of the BP2 promoter in the roots, stems, and leaves of transgenic tobacco plants were stable. Taken together, BP2 is more suitable than the BP1 promoter for the study and molecular breeding of stress-resistant soybean plants.

Genome-Wide Identification and Expression Analysis of the Dof Transcription Factor in Annual Alfalfa Medicago polymorpha

The Dof transcription factor is a plant-specific transcription gene family that plays various biological functions in plant development and stress response. However, no relevant research has been conducted on Medicago polymorpha. Here, 36 MpDof genes were identified in the M. polymorpha genome and further divided into 10 groups based on the comparative phylogenetic analysis. The essential information of MpDof genes, such as chromosomal localization, gene structure, conserved motifs, and selective pressures were systematically analyzed. All 36 MpDof genes were predicted to contain more cis-acting elements related to hormone response. MpDof24 and MpDof25 were predicted to interact with MpDof11 and MpDof26 to involve in the photoperiod blooms process. The MpDof genes showed a diverse expression pattern in different tissues. Notably, MpDof29 and MpDof31 were specifically expressed in the large pod and root, respectively, suggesting their crucial role in the pod and root development. qRT-PCR analysis indicated that the expression levels of MpDof10, MpDof25, MpDof26, and MpDof29 were obviously up-regulated under drought, salt, and cold stress. Collectively, genome-wide identification, evolutionary, and expression analysis of the Dof transcription gene family in M. polymorpha will provide new information to further understand and utilize the function of these Dof genes in Medicago plants.

Melatonin and Abiotic Stress Tolerance in Crop Plants

Increasing food demand by the growing human population and declining crop productivity due to climate change affect global food security. To meet the challenges, developing improved crops that can tolerate abiotic stresses is a priority. Melatonin in plants, also known as phytomelatonin, is an active component of the various cellular mechanisms that alleviates oxidative damage in plants, hence supporting the plant to survive abiotic stress conditions. Exogenous melatonin strengthens this defence mechanism by enhancing the detoxification of reactive by-products, promoting physiological activities, and upregulating stress-responsive genes to alleviate damage during abiotic stress. In addition to its well-known antioxidant activity, melatonin protects against abiotic stress by regulating plant hormones, activating ER stress-responsive genes, and increasing protein homoeostasis, heat shock transcription factors and heat shock proteins. Under abiotic stress, melatonin enhances the unfolded protein response, endoplasmic reticulum-associated protein degradation, and autophagy, which ultimately protect cells from programmed cell death and promotes cell repair resulting in increased plant survival.

Comparative phylogenomic insights of KCS and ELO gene families in Brassica species indicate their role in seed development and stress responsiveness

Very long-chain fatty acids (VLCFAs) possess more than twenty carbon atoms and are the major components of seed storage oil, wax, and lipids. FAE (Fatty Acid Elongation) like genes take part in the biosynthesis of VLCFAs, growth regulation, and stress responses, and are further comprised of KCS (Ketoacyl-CoA synthase) and ELO (Elongation Defective Elongase) sub-gene families. The comparative genome-wide analysis and mode of evolution of KCS and ELO gene families have not been investigated in tetraploid Brassica carinata and its diploid progenitors. In this study, 53 KCS genes were identified in B. carinata compared to 32 and 33 KCS genes in B. nigra and B. oleracea respectively, which suggests that polyploidization might has impacted the fatty acid elongation process during Brassica evolution. Polyploidization has also increased the number of ELO genes in B. carinata (17) over its progenitors B. nigra (7) and B. oleracea (6). Based on comparative phylogenetics, KCS, and ELO proteins can be classified into eight and four major groups, respectively. The approximate date of divergence for duplicated KCS and ELO genes varied from 0.03 to 3.20 million years ago (MYA). Gene structure analysis indicated that the maximum number of genes were intron-less and remained conserved during evolution. The neutral type of selection seemed to be predominant in both KCS and ELO genes evolution. String-based protein-protein interaction analysis suggested that bZIP53, a transcription factor might be involved in the activation of transcription of ELO/KCS genes. The presence of biotic and abiotic stress-related cis-regulatory elements in the promoter region suggests that both KCS and ELO genes might also play their role in stress tolerance. The expression analysis of both gene family members reflect their preferential seed-specific expression, especially during the mature embryo development stage. Furthermore, some KCS and ELO genes were found to be specifically expressed under heat stress, phosphorus starvation, and Xanthomonas campestris infection. The current study provides a basis to understand the evolution of both KCS and ELO genes in fatty acid elongation and their role in stress tolerance.

Genome-wide survey and expression analysis of Dof transcription factor family in sweetpotato shed light on their promising functions in stress tolerance

DNA-binding with one finger (Dof) transcription factors play a crucial role in plant abiotic stress regulatory networks, although massive Dofs have been systematically characterized in plants, they have not been identified in the hexaploid crop sweetpotato. Herein, 43 IbDof genes were detected to be disproportionally dispersed across 14 of the 15 chromosomes of sweetpotato, and segmental duplications were discovered to be the major driving force for the expansion of IbDofs. The collinearity analysis of IbDofs with their related orthologs from eight plants revealed the potential evolutionary history of Dof gene family. Phylogenetic analysis displayed that IbDof proteins were assigned into nine subfamilies, and the regularity of gene structures and conserved motifs was consistent with the subgroup classification. Additionally, five chosen IbDof genes were shown to be substantially and variably induced under various abiotic conditions (salt, drought, heat, and cold), as well as hormone treatments (ABA and SA), according to their transcriptome data and qRT-PCR experiments. Consistently, the promoters of IbDofs contained a number of cis-acting elements associated with hormone and stress responses. Besides, it was noted that IbDof2 had transactivation activity in yeasts, while IbDof-11/-16/-36 did not, and protein interaction network analysis and yeast two-hybrid experiments revealed a complicated interaction connection amongst IbDofs. Collectively, these data lay a foundation for further functional explorations of IbDof genes, especially with regards to the possible application of multiple IbDof members in breeding the tolerant plants.

Genome-wide identification and functional analysis of Dof transcription factor family in Camelina sativa

BACKGROUND

Dof transcription factors (TFs) containing C₂-C₂ zinc finger domains are plant-specific regulatory proteins, playing crucial roles in a variety of biological processes. However, little is known about Dof in Camelina sativa, an important oil crop worldwide, with high stress tolerance. In this study, a genome-wide characterization of Dof proteins is performed to examine their basic structural characteristics, phylogenetics, expression patterns, and functions to identify the regulatory mechanism underlying lipid/oil accumulation and the candidate Dofs mediating stress resistance regulation in C. sativa.

RESULTS

Total of 103 CsDof genes unevenly distributed on 20 chromosomes were identified from the C. sativa genome, and they were classified into four groups (A, B, C and D) based on the classification of Arabidopsis Dof gene family. All of the CsDof proteins contained the highly-conserved typic CX₂C-X₂₁-CX₂C structure. Segmental duplication and purifying selection were detected for CsDof genes. 61 CsDof genes were expressed in multiple tissues, and 20 of them showed tissue-specific expression patterns, suggesting that CsDof genes functioned differentially in different tissues of C. sativa. Remarkably, a set of CsDof members were detected to be possible involved in regulation of oil/lipid biosynthesis in C. sativa. Six CsDof genes exhibited significant expression changes in seedlings under salt stress treatment.

CONCLUSIONS

The present data reveals that segmental duplication is the key force responsible for the expansion of CsDof gene family, and a strong purifying pressure plays a crucial role in CsDofs' evolution. Several CsDof TFs may mediate lipid metabolism and stress responses in C. sativa. Several CsDof TFs may mediate lipid metabolism and stress responses in C. sativa. Collectively, our findings provide a foundation for deep understanding the roles of CsDofs and genetic improvements of oil yield and salt stress tolerance in this species and the related crops.

Genome-Wide Identification and Expression Analysis of Dof Transcription Factors in Lotus (Nelumbo nucifera Gaertn.)

Lotus (Nelumbo nucifera Gaertn.) is a traditional Chinese aquatic flower with high ornamental and economic value, but water salinity seriously affects lotus cultivation and distribution. The Dof transcription factors (TFs) play a crucial function in the regulatory network of growth and defense in plants. However, no systematic investigations of the Dof TFs in lotus have been performed. In this study, comprehensive searches of the lotus genome yielded 29 potential NnDofs. We carried out a series of standardized analyses, which include physical properties, multiple sequence alignment, phylogenetic analysis, gene structure, motif composition, cis-acting element prediction, chromosome distribution, and synteny analysis. The results showed that segment duplication probably caused the NnDofs gene family expansion. The potential functions of NnDofs in lotus development and stress conditions are speculated by promoter analysis. Furthermore, a complete expression investigation of NnDofs utilizing an RNA-seq atlas and quantitative real-time polymerase chain reaction (qRT-PCR) was performed. The majority of the NnDofs exhibit tissue-specific expression patterns, and many genes have been identified as being extremely sensitive to salt stressors. Overall, this study is the first to report a genome-wide assessment of the Dof family in lotus, and the findings offer vital insights for prospective functional studies on lotus salinity stress.

Selection and functional identification of Dof genes expressed in response to nitrogen in Populus simonii × Populus nigra

In plants, Dof transcription factors are involved in regulating the expression of a series of genes related to N uptake and utilization. Therefore, the present study investigated how DNA-binding with one finger (Dof) genes are expressed in response to nitrogen (N) form and concentration to clarify the role of Dof genes and their functions in promoting N assimilation and utilization in poplar. The basic characteristics and expression patterns of Dof genes in poplar were analyzed by the use of bioinformatics methods. Dof genes expressed in response to N were screened, after which the related genes were cloned and transformed into Arabidopsis thaliana; the physiological indexes and the expression of related genes were subsequently determined. The function of Dof genes was then verified in Arabidopsis thaliana plants grown in the presence of different N forms and concentrations. Forty-four Dof genes were identified, most of which were expressed in the roots and young leaves, and some of the Dof genes were expressed under ammonia- and nitrate-N treatments. Three genes related to N induction were cloned, their proteins were found to localize in the nucleus, and PnDof30 was successfully transformed into Arabidopsis thaliana for functional verification. On comparing Arabidopsis thaliana with WT Arabidopsis thaliana plants, Arabidopsis thaliana plants overexpressing the Dof gene grew better under low N levels; the contents of soluble proteins and chlorophyll significantly increased, while the soluble sugar content significantly decreased. The expressions of several AMT, NRT, and GS genes were upregulated, while the expressions of several others were downregulated, and the expression of PEPC and PK genes significantly increased. In addition, the activity of PEPC, PK, GS, and NR enzymes significantly increased. The results showed that overexpression of PnDof30 significantly increased the level of carbon and N metabolism and improved the growth of transgenic Arabidopsis thaliana plants under low-N conditions. The study revealed the biological significance of poplar Dof transcription factors in N response and regulation of related downstream gene expression and provided some meaningful clues to explain the huge difference between poplar and Arabidopsis thaliana transformed by exogenous Dof gene, which could promote the comprehensive understanding of the molecular mechanism of efficient N uptake and utilization in trees.

Metabolite Characteristics Analysis of Siliques and Effects of Lights on the Accumulation of Glucosinolates in Siliques of Rapeseed

Glucosinolates (GSLs) are naturally occurring secondary metabolites found in the Brassicaceae family, which mainly synthesize in the siliques with a wide range of functions. In this study, we investigated the effects of lights on metabolites in siliques of rapeseed through ultra high-performance liquid chromatography (UPLC)-heated electrospray ionization (HESI)-tandem mass spectrometry (MS/MS). A total of 249 metabolites, including 29 phenolic acids, 38 flavonoids, 22 GSLs, 93 uncalculated and 67 unknown compounds, were identified in siliques of rapeseed. Meanwhile, 62 metabolites showed significant differences after shading treatment, which were mainly GSLs and unknown compounds. Interestingly, the amounts of 10 GSLs had high accumulation levels in siliques, while the expression levels of their corresponding biosynthetic genes (AOP, GSL-OH, IGMT, and ST5a) were obviously reduced after shading treatment. Further evidence showed that the amounts of GSLs were significantly reduced in seeds, in accordance with the expression profiles of transporter genes (BnaGTRs). Our findings indicated that lights could affect the accumulation and transportation of GSLs from siliques to seeds in rapeseed. Therefore, this study facilitates a better understanding of metabolic characteristics of siliques and provides insight into the importance of light for GSLs accumulation and transportation in siliques and seeds of rapeseed.

Genome-wide analysis of Dof transcription factors and their response to cold stress in rice (Oryza sativa L.)

Background

Rice (Oryza sativa L.) is a food crop for humans worldwide. However, temperature has an effect during the vegetative and reproductive stages. In high-latitude regions where rice is cultivated, cold stress is a major cause of yield loss and plant death. Research has identified a group of plant-specific transcription factors, DNA binding with one zinc fingers (DOFs), with a diverse range of functions, including stress signaling and stress response during plant growth. The aim of this study was to identify Dof genes in two rice subspecies, indica and japonica, and screen for Dof genes that may be involved in cold tolerance during plant growth.

Results

A total of 30 rice Dofs (OsDofs) were identified using bioinformatics and genome-wide analyses and phylogenetically analyzed. The 30 OsDOFs were classified into six subfamilies, and 24 motifs were identified based on protein sequence alignment. The chromosome locations of OsDofs were determined and nine gene duplication events were identified. A joint phylogenetic analysis was performed on DOF protein sequences obtained from four monocotyledon species to examine the evolutionary relationship of DOF proteins. Expression profiling of OsDofs from two japonica cultivars (Longdao5, which is cold-tolerant, and Longjing11, which is cold-sensitive) revealed that OsDof1 and OsDof19 are cold-inducible genes. We examined the seed setting rates in OsDof1- and OsDof19-overexpression and RNAi lines and found that OsDof1 showed a response to cold stress.

Conclusions

Our investigation identified OsDof1 as a potential target for genetic breeding of rice with enhanced cold tolerance.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-021-08104-0.