WRKY Transcription Factors in Medicago sativa L.: Genome-Wide Identification and Expression Analysis Under Abiotic Stress

MsWRKY44 regulates Mg-K homeostasis of shoots and promotes alfalfa sensitivities to acid and Al stresses

Mg-K homeostasis is essential for plant response to abiotic stress, but its regulation remains largely unknown. MsWRKY44 cloned from alfalfa was highly expressed in leaves and petioles. Overexpression of it inhibited alfalfa growth, and promoted leaf senescence and alfalfa sensitivities to acid and Al stresses. The leaf tips, margins and interveins of old leaves occurred yellow spots in MsWRKY44-OE plants under pH4.5 and pH4.5 +Al conditions. Meanwhile, Mg-K homeostasis was substantially changed with reduction of K accumulation and increases of Mg as well as Al accumulation in shoots of MsWRKY44-OE plants. Further, MsWRKY44 was found to directly bind to the promoters of MsMGT7 and MsCIPK23, and positively activated their expression. Transiently overexpressed MsMGT7 and MsCIPK23 in tobacco leaves increased the Mg and Al accumulations but decreased K accumulation. These results revealed a novel regulatory module MsWRKY44-MsMGT7/MsCIPK23, which affects the transport and accumulation of Mg and K in shoots, and promotes alfalfa sensitivities to acid and Al stresses.

Genome-wide identification of JAZ gene family members in autotetraploid cultivated alfalfa (Medicago sativa subsp. sativa) and expression analysis under salt stress

BACKGROUND

Jasmonate ZIM-domain (JAZ) proteins, which act as negative regulators in the jasmonic acid (JA) signalling pathway, have significant implications for plant development and response to abiotic stress.

RESULTS

Through a comprehensive genome-wide analysis, a total of 20 members of the JAZ gene family specific to alfalfa were identified in its genome. Phylogenetic analysis divided these 20 MsJAZ genes into five subgroups. Gene structure analysis, protein motif analysis, and 3D protein structure analysis revealed that alfalfa JAZ genes in the same evolutionary branch share similar exon‒intron, motif, and 3D structure compositions. Eight segmental duplication events were identified among these 20 MsJAZ genes through collinearity analysis. Among the 32 chromosomes of the autotetraploid cultivated alfalfa, there were 20 MsJAZ genes distributed on 17 chromosomes. Extensive stress-related cis-acting elements were detected in the upstream sequences of MsJAZ genes, suggesting that their response to stress has an underlying function. Furthermore, the expression levels of MsJAZ genes were examined across various tissues and under the influence of salt stress conditions, revealing tissue-specific expression and regulation by salt stress. Through RT‒qPCR experiments, it was discovered that the relative expression levels of these six MsJAZ genes increased under salt stress.

CONCLUSIONS

In summary, our study represents the first comprehensive identification and analysis of the JAZ gene family in alfalfa. These results provide important information for exploring the mechanism of JAZ genes in alfalfa salt tolerance and identifying candidate genes for improving the salt tolerance of autotetraploid cultivated alfalfa via genetic engineering in the future.

MsWRKY33 increases alfalfa (Medicago sativa L.) salt stress tolerance through altering the ROS scavenger via activating MsERF5 transcription

Alfalfa (Medicago sativa L.) is considered to be the most important forage crop on a global scale. Nevertheless, soil salinity significantly decreases productivity, seriously threatening food security worldwide. One viable strategy is to explore salt stress-responsive factors and elucidate their underlying molecular mechanism, and utilize them in further alfalfa breeding. In the present study, we designated MsWRKY33 as a representative salt stress-responsive factor preferentially expressed in alfalfa roots and leaves. Subsequently, it was demonstrated that MsWRKY33 was localized in the cell nucleus, and functioned as a transcriptional activator of the W-box element. Transgenic alfalfa overexpressing MsWRKY33 displayed enhanced salt stress tolerance and antioxidant activities with no significant difference in other agronomic traits. Transcriptome profiling of MsWRKY33 transgenic alfalfa under control and salt treatment unveiled significantly altered expression of reactive oxygen species (ROS) scavenger genes in transgenic alfalfa. Subsequent examination revealed that MsWRKY33 binded to the promoter of MsERF5, activating its expression and consequently fine-tuning the ROS-scavenging enzyme activity. Furthermore, MsWRKY33 interacted with the functional fragment of MsCaMBP25, which participates in Ca2+ signaling transduction. Collectively, this research offers new insight into the molecular mechanism of alfalfa salt stress tolerance and highlights the potential utility of MsWRKY33 in alfalfa breeding.

Genomic identification and expression profiling of WRKY genes in alfalfa (Medicago sativa) elucidate their responsiveness to seed vigor

BACKGROUND

Seed aging is a critical factor contributing to vigor loss, leading to delayed forage seed germination and seedling growth. Numerous studies have revealed the regulatory role of WRKY transcription factors in seed development, germination, and seed vigor. However, a comprehensive genome-wide analysis of WRKY genes in Zhongmu No.1 alfalfa has not yet been conducted.

RESULTS

In this study, a total of 91 MsWRKY genes were identified from the genome of alfalfa. Phylogenetic analysis revealed that these MsWRKY genes could be categorized into seven distinct subgroups. Furthermore, 88 MsWRKY genes were unevenly mapped on eight chromosomes in alfalfa. Gene duplication analysis revealed segmental duplication as the principal driving force for the expansion of this gene family during the course of evolution. Expression analysis of the 91 MsWRKY genes across various tissues and during seed germination exhibited differential expression patterns. Subsequent RT-qPCR analysis highlighted significant induction of nine selected MsWRKY genes in response to seed aging treatment, suggesting their potential roles in regulating seed vigor.

CONCLUSION

This study investigated WRKY genes in alfalfa and identified nine candidate WRKY transcription factors involved in the regulation of seed vigor. While this finding provides valuable insights into understanding the molecular mechanisms underlying vigor loss and developing new strategies to enhance alfalfa seed germinability, further research is required to comprehensively elucidate the precise pathways through which the MsWRKY genes modulate seed vigor.

Plant salinity stress, sensing, and its mitigation through WRKY

Salinity or salt stress has deleterious effects on plant growth and development. It imposes osmotic, ionic, and secondary stresses, including oxidative stress on the plants and is responsible for the reduction of overall crop productivity and therefore challenges global food security. Plants respond to salinity, by triggering homoeostatic mechanisms that counter salt-triggered disturbances in the physiology and biochemistry of plants. This involves the activation of many signaling components such as SOS pathway, ABA pathway, and ROS and osmotic stress signaling. These biochemical responses are accompanied by transcriptional modulation of stress-responsive genes, which is mostly mediated by salt-induced transcription factor (TF) activity. Among the TFs, the multifaceted significance of WRKY proteins has been realized in many diverse avenues of plants' life including regulation of plant stress response. Therefore, in this review, we aimed to highlight the significance of salinity in a global perspective, the mechanism of salt sensing in plants, and the contribution of WRKYs in the modulation of plants' response to salinity stress. This review will be a substantial tool to investigate this problem in different perspectives, targeting WRKY and offering directions to better manage salinity stress in the field to ensure food security.

Genomic Identification and Expression Profiling of Lesion Simulating Disease Genes in Alfalfa (Medicago sativa) Elucidate Their Responsiveness to Seed Vigor

Seed aging, a common physiological phenomenon during forage seed storage, is a crucial factor contributing to a loss of vigor, resulting in delayed seed germination and seedling growth, as well as limiting the production of hay. Extensive bodies of research are dedicated to the study of seed aging, with a particular focus on the role of the production and accumulation of reactive oxygen species (ROS) and the ensuing oxidative damage during storage as a primary cause of decreases in seed vigor. To preserve optimal seed vigor, ROS levels must be regulated. The excessive accumulation of ROS can trigger programmed cell death (PCD), which causes the seed to lose vigor permanently. LESION SIMULATING DISEASE (LSD) is one of the proteins that regulate PCD, encodes a small C2C2 zinc finger protein, and plays a molecular function as a transcriptional regulator and scaffold protein. However, genome-wide analysis of LSD genes has not been performed for alfalfa (Medicago sativa), as one of the most important crop species, and, presently, the molecular regulation mechanism of seed aging is not clear enough. Numerous studies have also been unable to explain the essence of seed aging for LSD gene regulating PCD and affecting seed vigor. In this study, we obtained six MsLSD genes in total from the alfalfa (cultivar Zhongmu No. 1) genome. Phylogenetic analysis demonstrated that the MsLSD genes could be classified into three subgroups. In addition, six MsLSD genes were unevenly mapped on three chromosomes in alfalfa. Gene duplication analysis demonstrated that segmental duplication was the key driving force for the expansion of this gene family during evolution. Expression analysis of six MsLSD genes in various tissues and germinating seeds presented their different expressions. RT-qPCR analysis revealed that the expression of three MsLSD genes, including MsLSD2, MsLSD5, and MsLSD6, was significantly induced by seed aging treatment, suggesting that they might play an important role in maintaining seed vigor. Although this finding will provide valuable insights into unveiling the molecular mechanism involved in losing vigor and new strategies to improve alfalfa seed germinability, additional research must comprehensively elucidate the precise pathways through which the MsLSD genes regulate seed vigor.

Genome-wide analysis of the WRKY genes and their important roles during cold stress in white clover

Background

White clover (Trifolium repens L) is a high-quality forage grass with a high protein content, but it is vulnerable to cold stress, which can negatively affect its growth and development. WRKY transcription factor is a family of plant transcription factors found mainly in higher plants and plays an important role in plant growth, development, and stress response. Although WRKY transcription factors have been studied extensively in other plants, it has been less studied in white clover.

Methods and Results

In the present research, we have performed a genome-wide analysis of the WRKY gene family of white clover, in total, there were 145 members of WRKY transcription factors identified in white clover. The characterization of the TrWRKY genes was detailed, including conserved motif analysis, phylogenetic analysis, and gene duplication analysis, which have provided a better understanding of the structure and evolution of the TrWRKY genes in white clover. Meanwhile, the genetic regulation network (GRN) containing TrWRKY genes was reconstructed, and Gene Ontology (GO) annotation analysis of these function genes showed they contributed to regulation of transcription process, response to wounding, and phosphorylay signal transduction system, all of which were important processes in response to abiotic stress. To determine the TrWRKY genes function under cold stress, the RNA-seq dataset was analyzed; most of TrWRKY genes were highly upregulated in response to cold stress, particularly in the early stages of cold stress. These results were validated by qRT-PCR experiment, implying they are involved in various gene regulation pathways in response to cold stress.

Conclusion

The results of this study provide insights that will be useful for further functional analyses of TrWRKY genes in response to biotic or abiotic stresses in white clover. These findings are likely to be useful for further research on the functions of TrWRKY genes and their role in response to cold stress, which is important to understand the molecular mechanism of cold tolerance in white clover and improve its cold tolerance.

Genome-Wide Identification and Characterization of the Msr Gene Family in Alfalfa under Abiotic Stress

Alfalfa (Medicago sativa) is an important leguminous forage, known as the "The Queen of Forages". Abiotic stress seriously limits the growth and development of alfalfa, and improving the yield and quality has become an important research area. However, little is known about the Msr (methionine sulfoxide reductase) gene family in alfalfa. In this study, 15 Msr genes were identified through examining the genome of the alfalfa "Xinjiang DaYe". The MsMsr genes differ in gene structure and conserved protein motifs. Many cis-acting regulatory elements related to the stress response were found in the promoter regions of these genes. In addition, a transcriptional analysis and qRT-PCR (quantitative reverse transcription PCR) showed that MsMsr genes show expression changes in response to abiotic stress in various tissues. Overall, our results suggest that MsMsr genes play an important role in the response to abiotic stress for alfalfa.

Genome-Wide Analysis of WRKY Transcription Factors Involved in Abiotic Stress and ABA Response in Caragana korshinskii

The WRKY transcription factor family plays a vital role in plant development and environmental response. However, the information of WRKY genes at the genome-wide level is rarely reported in Caragana korshinskii. In this study, we identified and renamed 86 CkWRKY genes, which were further classified into three groups through phylogenetic analysis. Most of these WRKY genes were clustered and distributed on eight chromosomes. Multiple sequence alignment revealed that the conserved domain (WRKYGQK) of the CkWRKYs was basically consistent, but there were also six variation types (WRKYGKK, GRKYGQK, WRMYGQK, WRKYGHK, WKKYEEK and RRKYGQK) that appeared. The motif composition of the CkWRKYs was quite conservative in each group. In general, the number of WRKY genes gradually increased from lower to higher plant species in the evolutionary analysis of 28 species, with some exceptions. Transcriptomics data and RT-qPCR analysis showed that the CkWRKYs in different groups were involved in abiotic stresses and ABA response. Our results provided a basis for the functional characterization of the CkWRKYs involved in stress resistance in C. korshinskii.

Genome-Wide Analysis of Proline-Rich Extensin-Like Receptor Kinases (PERKs) Gene Family Reveals Their Roles in Plant Development and Stress Conditions in Oryza sativa L

Proline-rich extensin-like receptor kinases (PERKs) play a crucial role in a wide range of biological processes in plants. In model plants like Arabidopsis, the PERK gene family has been well investigated. Conversely, no information available on the PERK gene family and their biological functions largely remained unknown in rice. This study analyzed the basic physicochemical properties, phylogeny, gene structure, cis-acting elements, Gene ontology (GO) annotation and protein-protein interaction of OsPERK gene family members using various bioinformatics tools based on the whole-genome data of O. sativa. Thus, in this work, 8 PERK genes in rice were identified, and their roles in plant development, growth, and response to various stresses were studied. A phylogenetic study revealed that OsPERKs are grouped into seven classes. Chromosomal mapping also displayed that 8 PERK genes were unevenly distributed on 12 chromosomes. Further, the prediction of subcellular localization indicated that OsPERKs were mainly located at the endomembrane system. Gene structure analysis of OsPERKs has shown a distinctive evolutionary path. In addition, synteny analysis exhibited the 40 orthologous gene pairs in Arabidopsis thaliana, Triticum aestivum, Hordeum vulgare and Medicago truncatula. Furthermore, Ka to Ks proportion shows that most OsPERK genes experienced resilient purifying selection during evolutionary processes. The OsPERK promoters contained several cis-acting regulatory, which are crucial for plant development processes, phytohormone signaling, stress, and defense response. Moreover, the expression pattern of OsPERK family members showed differential expression patterns in different tissues and various stress conditions. Taken together, these results provide clear messages for a better understanding the roles of OsPERK genes in various development stages, tissues, and multifactorial stress as well as enriched the related research of OsPERK family members in rice.

Uncovering early transcriptional regulation during adventitious root formation in Medicago sativa

BACKGROUND

Alfalfa (Medicago sativa L.) as an important legume plant can quickly produce adventitious roots (ARs) to form new plants by cutting. But the regulatory mechanism of AR formation in alfalfa remains unclear.

RESULTS

To better understand the rooting process of alfalfa cuttings, plant materials from four stages, including initial separation stage (C stage), induction stage (Y stage), AR primordium formation stage (P stage) and AR maturation stage (S stage) were collected and used for RNA-Seq. Meanwhile, three candidate genes (SAUR, VAN3 and EGLC) were selected to explore their roles in AR formation. The numbers of differentially expressed genes (DEGs) of Y-vs-C (9,724) and P-vs-Y groups (6,836) were larger than that of S-vs-P group (150), indicating highly active in the early AR formation during the complicated development process. Pathways related to cell wall and sugar metabolism, root development, cell cycle, stem cell, and protease were identified, indicating that these genes were involved in AR production. A large number of hormone-related genes associated with the formation of alfalfa ARs have also been identified, in which auxin, ABA and brassinosteroids are thought to play key regulatory roles. Comparing with TF database, it was found that AP2/ERF-ERF, bHLH, WRKY, NAC, MYB, C2H2, bZIP, GRAS played a major regulatory role in the production of ARs of alfalfa. Furthermore, three identified genes showed significant promotion effect on AR formation.

CONCLUSIONS

Stimulation of stem basal cells in alfalfa by cutting induced AR production through the regulation of various hormones, transcription factors and kinases. This study provides new insights of AR formation in alfalfa and enriches gene resources in crop planting and cultivation.

WRKY transcription factors: evolution, regulation, and functional diversity in plants

The recent advancements in sequencing technologies and informatic tools promoted a paradigm shift to decipher the hidden biological mysteries and transformed the biological issues into digital data to express both qualitative and quantitative forms. The transcriptomic approach, in particular, has added new dimensions to the versatile essence of plant genomics through the large and deep transcripts generated in the process. This has enabled the mining of super families from the sequenced plants, both model and non-model, understanding their ancestry, diversity, and evolution. The elucidation of the crystal structure of the WRKY proteins and recent advancement in computational prediction through homology modeling and molecular dynamic simulation has provided an insight into the DNA-protein complex formation, stability, and interaction, thereby giving a new dimension in understanding the WRKY regulation. The present review summarizes the functional aspects of the high volume of sequence data of WRKY transcription factors studied from different species, till date. The review focuses on the dynamics of structural classification and lineage in light of the recent information. Additionally, a comparative analysis approach was incorporated to understand the functions of the identified WRKY transcription factors subjected to abiotic (heat, cold, salinity, senescence, dark, wounding, UV, and carbon starvation) stresses as revealed through various sets of studies on different plant species. The review will be instrumental in understanding the events of evolution and the importance of WRKY TFs under the threat of climate change, considering the new scientific evidences to propose a fresh perspective.

Genome-wide analysis of WRKY transcription factor genes in Toona sinensis: An insight into evolutionary characteristics and terpene synthesis

WRKY transcription factors (TFs), one of the largest TF families, serve critical roles in the regulation of secondary metabolite production. However, little is known about the expression pattern of WRKY genes during the germination and maturation processes of Toona sinensis buds. In the present study, the new assembly of the T. sinensis genome was used for the identification of 78 TsWRKY genes, including gene structures, phylogenetic features, chromosomal locations, conserved protein domains, cis-regulatory elements, synteny, and expression profiles. Gene duplication analysis revealed that gene tandem and segmental duplication events drove the expansion of the TsWRKYs family, with the latter playing a key role in the creation of new TsWRKY genes. The synteny and evolutionary constraint analyses of the WRKY proteins among T. sinensis and several distinct species provided more detailed evidence of gene evolution for TsWRKYs. Besides, the expression patterns and co-expression network analysis show TsWRKYs may multi-genes co-participate in regulating terpenoid biosynthesis. The findings revealed that TsWRKYs potentially play a regulatory role in secondary metabolite synthesis, forming the basis for further functional characterization of WRKY genes with the intention of improving T. sinensis.

Genome-Wide Identification of bHLH Transcription Factor in Medicago sativa in Response to Cold Stress

Alfalfa represents one of the most important legume forages, and it is also applied as an organic fertilizer to improve soil quality. However, this perennial plant is native to warmer temperate regions, and its valuable cold-acclimation-related regulatory mechanisms are still less known. In higher plants, the bHLH transcription factors play pleiotropic regulatory roles in response to abiotic stresses. The recently released whole genome sequencing data of alfalfa allowed us to identify 469 MsbHLHs by multi-step homolog search. Herein, we primarily identified 65 MsbHLH genes that significantly upregulated under cold stress, and such bHLHs were classified into six clades according to their expression patterns. Interestingly, the phylogenetic analysis and conserved motif screening of the cold-induced MsbHLHs showed that the expression pattern is relatively varied in each bHLH subfamily, this result indicating that the 65 MsbHLHs may be involved in a complex cold-responsive regulatory network. Hence, we analyzed the TFBSs at promoter regions that unraveled a relatively conserved TFBS distribution with genes exhibiting similar expression patterns. Eventually, to verify the core components involved in long-term cold acclimation, we examined transcriptome data from a freezing-tolerant species (cv. Zhaodong) in the field and compared the expression of cold-sensitive/tolerant subspecies of alfalfa, giving 11 bHLH as candidates, which could be important for further cold-tolerance enhancement and molecular breeding through genetic engineering in alfalfa.

Genome-Wide Identification and Expression Analysis of HSF Transcription Factors in Alfalfa (Medicago sativa) under Abiotic Stress

Alfalfa (Medicago sativa) is one of the most important legume forage species in the world. It is often affected by several abiotic stressors that result in reduced yields and poor growth. Therefore, it is crucial to study the resistance of M. sativa to abiotic stresses. Heat shock transcription factors (HSF) are key players in a number of transcriptional regulatory pathways. These pathways play an essential role in controlling how plants react to different abiotic stressors. Studies on the HSF gene family have been reported in many species but have not yet undergone a thorough analysis in M. sativa. Therefore, in order to identify a more comprehensive set of HSF genes, from the genomic data, we identified 16 members of the MsHSF gene, which were unevenly distributed over six chromosomes. We also looked at their gene architectures and protein motifs, and phylogenetic analysis allowed us to divide them into 3 groups with a total of 15 subgroups. Along with these aspects, we then examined the physicochemical properties, subcellular localization, synteny analysis, GO annotation and enrichment, and protein interaction networks of amino acids. Finally, the analysis of 16 MsHSF genes' expression levels across all tissues and under four abiotic stresses using publicly available RNA-Seq data revealed that these genes had significant tissue-specific expression. Moreover, the expression of most MsHSF genes increased dramatically under abiotic stress, further validating the critical function played by the MsHSF gene family in abiotic stress. These results provided basic information about MsHSF gene family and laid a foundation for further study on the biological role of MsHSF gene in response to stress in M. sativa.

Genome-Wide Identification of the Q-type C2H2 Transcription Factor Family in Alfalfa (Medicago sativa) and Expression Analysis under Different Abiotic Stresses

Q-type C2H2 zinc-finger protein (C2H2-ZFP) transcription factors are associated with many plant growth development and environmental stress responses. To date, there have been few analyses of the Q-type C2H2-ZFP gene family in alfalfa (Medicago sativa subsp. sativa). In this study, we identified 58 Q-type C2H2-ZFPs across the entire alfalfa genome, and the gene structure, motif composition, chromosomal mapping, and cis-regulatory elements were explored, as well as the expression profiles of specific tissues and the response under different abiotic stresses. According to their phylogenetic features, these 58 MsZFPs were divided into 12 subgroups. Synteny analysis showed that duplication events play a vital role in the expansion of the MsZFP gene family. The collinearity results showed that a total of 26 and 42 of the 58 MsZFP genes were homologous with Arabidopsis and M. truncatula, respectively. The expression profiles showed that C2H2-ZFP genes played various roles in different tissues and abiotic stresses. The results of subsequent quantitative real-time polymerase chain reaction (qRT-PCR) showed that the nine selected MsZFP genes were rapidly induced under different abiotic stresses, indicating that C2H2-ZFP genes are closely related to abiotic stress. This study provides results on MsZFP genes, their response to various abiotic stresses, and new information on the C2H2 family in alfalfa.

Genome-wide identification of the MADS-box transcription factor family in autotetraploid cultivated alfalfa (Medicago sativa L.) and expression analysis under abiotic stress

Background

Alfalfa, the “queen of forage”, is the most extensively cultivated forage legume in the world. The development and yield of alfalfa are seriously limited by abiotic stress. MADS-box transcription factors are one of the largest gene families and play a pivotal role in plant development and abiotic stress. However, little is known regarding the MADS-box transcription factors in autotetraploid cultivated alfalfa.

Results

In the present study, we identified 120 MsMADS-box genes in the alfalfa genome. Phylogenetic analysis indicated that 75 type-I MsMADS-box genes were classified into the Mα, Mβ, and Mγ subgroups, and 45 type-II MsMADS-box genes were classified into 11 subgroups. The promoter region of MsMADS-box genes containing several hormone and stress related elements. Chromosomal location analysis revealed that 117 MsMADS-box genes were unevenly distributed on 32 chromosomes, and the remaining three genes were located on unmapped scaffolds. A total of nine pairs of segmental duplications and four groups of tandem duplications were found. Expression analysis showed that MsMADS-box genes were differentially expressed in various tissues and under abiotic stresses. qRT-PCR analysis revealed that the expression profiles of eight selected MsMADS-box genes were distinct under various stresses.

Conclusions

In this study, MsMADS-box genes were identified in the cultivated alfalfa genome based on autotetraploid level, and further confirmed by Gene Ontology (GO) analysis, phylogenetic analysis, sequence features and expression analysis. Taken together, these findings will provide clues for further study of MsMADS-box functions and alfalfa molecular breeding.

Our study is the first to systematically identify and characterize the MADS-box transcription factors in autotetraploid cultivated alfalfa (Medicago sativa L.), and eight MsMADS-box genes were significantly involved in response to various stresses.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-021-07911-9.

Development and validation of a hypoxia-related gene pair signature to predict overall survival in head and neck squamous cell carcinoma

OBJECTIVE

Head and neck squamous cell carcinoma (HNSCC) are a highly aggressive tumor with an extremely poor prognosis. Thus, we aimed to develop and validate a robust prognostic signature that can estimate the prognosis for HNSCC.

METHODS

Data on gene expressions and clinical were downloaded from TCGA and GEO database. To develop the best prognosis signature, a LASSO Cox Regression model was employed. Time-dependent receiver-operating characteristic (ROC) was used to determine the best cut-off value. Patients were divided into high-risk and low-risk hypoxia groups according to cut-off value. Survival differences were evaluated by log-rank test, while multivariate analysis was performed by a Cox proportional hazards model.

RESULTS

A 17-HRGPs composed of 24 unique genes was constructed, which was significantly related to OS. In the TCGA and GEO datasets, patients in the high hypoxia risk group have a poor prognosis (TCGA: P < 0.001, GEO: P < 0.05). After adjusting for other clinicopathological parameters, the 17-HRGP signature was independent prognostic factors in patients with HNSCC (P < 0.05). Functional analysis revealed that mRNA binding, gene silencing by RNA, RNA binding involved in posttranscriptional gene silencing signaling pathway were enriched in the low-risk groups. For this model, C-index was 0.684, which was higher than that of many established risk models. Macrophages M0, Mast cells activated, NK cells resting, T cells CD4 memory resting, etc. were significantly higher in the high-risk group, and B cells memory, Plasma cells, T cells follicular helper, T cells gamma delta, T cells CD8, etc. were significantly higher in the low-risk group.

CONCLUSION

In summary, our study constructed a robust HRGPs signature as molecular markers for predicting the outcome of HNSCC patients.