SERK Genes Research Articles

Differential expression of genes potentially related to the callogenesis and in situ hybridization of SERK gene in macaw palm (Acrocomia aculeata Jacq.) Lodd. ex Mart.

For the purpose of understanding the molecular processes triggered during callus formation in macaw palm, the expression of seven genes potentially involved in this process, identified in previous studies and from the literature, was investigated by RT-qPCR. In addition, in situ hybridization of the SERK gene was performed. Leaf tissues from adult plants from two macaw palm accession were inoculated in a medium combined with Picloram at a concentration of 450 μM to induce callus. The expression analysis was performed from leaf samples from two accessions of different origins (Municipalities of Tiros, MG, and Buriti Vermelho, DF, Brazil), which are characterized as non-responsive (NR) and responsive (R), respectively. The material was collected before callus induction (0 DAI, initial day) and 120 days after callus induction (120 DAI). Genes related to development (SERK, OASA, EF1, ANN1) and stress (LEA, CAT2, and MDAR5) were evaluated. The results obtained showed that all the genes involved with the development had their expressions downregulated at 0 DAI when the accession R was compared with the accession NR. On the other hand, it was possible to observe that these genes were upregulated at 120 DAI. The LEA stress gene showed a tendency to increase expression in the NR accession, while the R accession showed decreased expression and the CAT2 and MDAR5 genes showed upregulation in both accessions. In situ hybridization showed SERKtranscriptsin the vascular bundles, indicating the expression of SERK in this region, in addition to its expression in calluses. The results obtained in this study support our hypothesis that the regulation of genes involved in the control of oxidative stress and development is crucial for the formation of calluses in macaw palm.

Comparative Transcriptome Analysis between Embryogenic and Non-Embryogenic Callus of Davidia involucrata

Davidia involucrata Baill. (D. involucrata), a rare and endangered wild plant, is native to China and is globally recognized as an ornamental tree species. However, D. involucrata exhibits inherent biological characteristics that contribute to its low reproductive efficiency. To address this challenge, somatic embryogenesis, a biotechnological method, offers numerous advantages, including enhanced reproductive efficiency, a large reproductive coefficient, and a complete structural composition. Consequently, somatic embryogenesis holds significant value in the propagation and genetic improvement of this particular tree species. In a previous study, we utilized immature zygotic embryos of D. involucrata as explants and induced somatic embryogenesis from embryogenic callus, thereby establishing a rapid propagation and plant regeneration scheme. In this study, we utilized Illumina RNA sequencing to compare the transcriptomes of the embryogenic callus (EC) and non-embryogenic callus (NEC) of D. involucrata. The analysis revealed 131,109 unigenes assembled from EC and NEC, and 12,806 differentially expressed genes (DEGs) were identified. To verify the authenticity of the transcriptome sequencing results, qRT-PCR was performed and 16 DEGs were screened, with the stable reference gene UBQ being selected. Our analysis focused on genes related to plant growth regulators and somatic embryogenesis, such as the Aux, IAA, ARF, GH3, AHP, ARR, CYCD, BBM, WUS, GRF, SERK, and WOX gene families. We found that certain genes in these families were significantly upregulated in EC induction compared to NEC, indicating that they play crucial roles in D. involucrata cell proliferation, differentiation, and cell totipotency. These results offer new insights into the role of these gene families in EC, and may guide efforts to improve the somatic embryo induction, culture conditions, and genetic transformation efficiency of D. involucrata.

Identification of the SERK Gene Family in Paulownia fortunei and Its Involvement in the Response to Biotic and Abiotic Stresses

Identification of the SERK Gene Family in Paulownia fortunei and Its Involvement in the Response to Biotic and Abiotic Stresses

Cloning and expression analysis of SERK1 gene in Diospyros lotus.

Somatic embryogenesis receptor-like kinases (SERKs), a subfamily of receptor-like kinases, play important roles in response to abiotic stresses in addition to apomictic reproductive development in numerous plant species. The purpose of the present work was to determine if an ortholog of the SERK gene is present in the Diospyros lotus genome, isolate it and analyze its expression during embryogeny and abiotic stress. An ortholog of the SERK gene was isolated from the D. lotus genome, and designated as DlSERK1. The physical and chemical properties, protein structure, and evolutionary relationship of the DlSERK1 protein were analyzed by bioinformatics methods, and the expression of DlSERK1 gene during embryonic development and under low-temperature, salt, and drought stresses was examined through real-time quantitative PCR analysis. DlSERK1 contained 1,881 bp open reading frame encoding 626 amino acids, with a molecular mass of 69.18 kDa and pI of 5.34. DlSERK1 had strong hydrophilic property, signal peptide cleavage sites, and two transmembrane regions, indicating that DlSERK1 is a secretory protein. The secondary structure of DlSERK1 was consistent with the tertiary structure, both of which were dominated by random curls and alpha-helices. DlSERK1 had the typical structure of SERK proteins, and harbored multiple phosphorylation and glycosylation sites. Quantitative analysis showed that DlSERK1 was expressed during the embryonic development period, and the highest expression level was at 10 days post-flowering. The DlSERK1 expression level was down-regulated under low-temperature stress and up-regulated under drought and salt stresses. Our study showed that DlSERK1 was expressed in embryo development and could respond to low-temperature, drought, and salt stresses, which lays a foundation for further research on the function of SERK1 in the apomixis growth and development of environmental adaptation in D. lotus.

Expression and in silico analysis of the pineapple SERK gene homologues during in vitro regeneration and induced Fusarium infection

Expression and in silico analysis of the pineapple SERK gene homologues during in vitro regeneration and induced Fusarium infection

A peak in global DNA methylation is a key step to initiate the somatic embryogenesis of coconut palm (Cocos nucifera L).

DNA methylation, morphogenesis and gene expression during the somatic embryogenesis of Coconut are affected by 5-Azacytidine pretreatments, indicating that DNA methylation is an important factor throughout this process. Somatic embryogenesis (SE) is a process that can aid in the production of elite Cocos nucifera palms. It has been well established that epigenetic mechanisms are regulators of cell differentiation programs; however, their role in the coconut somatic embryogenesis has not yet been addressed. To this end, the morphogenetic changes, the global DNA methylation and the expression profiles of the SE-related genes and DNA methyltransferases genes were evaluated during the SE process, with and without the presence of 5-Azacytidine (AzaC). The results show that three days of pretreatments with 15µM and 20µM of AzaC significantly increased early somatic embryo formation (four- and tenfold, respectively). A clear peak of the global percentage of DNA methylation (approximately 13%) was determined at the beginning of the culture, followed by a re-establishing stage and a steady increase thereafter; in all cases, the levels of DNA methylation were lower after the pretreatments with AzaC. Additionally, the expression profiles of the SERK, WUS, BBM and LEC genes are modulated during the SE process and the pretreatments with AzaC affect the expression profiles of these genes, even at early stages. Furthermore, increased levels of expression were observed for the genes encoding for DNA methyltransferases (MET, CMT and DRM) at early and late stages of SE, indicating that DNA methylation is an important factor throughout the SE.

Characterization of Aquilaria malaccensis Callus Cells using SEM and Somatic Embryogenesis Associated Genes Identification

Aquilaria malaccensis or gaharu is one of Malaysia’s top tropical resources that is being protected and conserved. Somatic embryogenesis is a plant tissue culture method used most extensively in commercial micropropagation systems and conservation purposes. This study aims to optimize callus induction techniques for somatic embryogenesis study using Scanning Electron Microscope (SEM) and Polymerase Chain Reaction (PCR) analysis. In this study, callus was induced on Murashige and Skoog’s (MS) medium supplemented with a combination of plant growth regulators and optimized parameters (explant used, sterilization techniques, media content, pH media, plant growth regulators, incubation condition, and incubation temperature). The cells were subcultured for long-term callus maintenance and subjected to SEM analysis for somatic embryogenesis confirmation. Four set of genes associated to somatic embryogenesis (SERK, BBM, LEC1, and WOX) were studied based on National Centre for Biotechnology Information database and literatures. The data obtained were used for primer design and gene amplification using 3 different tissues (leaf, stem, callus).The highest frequencies of callus induction were observed on Murashikage and Skoog medium supplemented with 6-Benzylaminopurine and 1-Naphthaleneacetic acid together with optimized growth parameters. SEM analysis showed embryogenic characteristics in cells of the yellow compact calli evidenced by the presence of small and isodiametric cells. Only SERK gene was successfully amplified and enable to proceed with in silico analysis. This study provides fundamental results for genetic conservation effort of A. malaccensis related to somatic embryogenesis study.

Genome-wide identification of SERK genes in apple and analyses of their role in stress responses and growth

BackgroundSomatic embryogenesis receptor-like kinases (SERKs) are leucine-rich repeat receptor-like kinases associated with various signaling pathways. These kinases have a relationship with stress signals, and they are also believed to be important for regulating plant growth. However, information about this protein family in apple is limited.ResultsTwelve apple SERK genes distributed across eight chromosomes were identified. These genes clustered into three distinct groups in a phylogenetic analysis. All of the encoded proteins contained typical SERK domains. The chromosomal locations, gene/protein structures, synteny, promoter sequences, protein–protein interactions, and physicochemical characteristics of MdSERK genes were analyzed. Bioinformatics analyses demonstrated that gene duplications have likely contributed to the expansion and evolution of SERK genes in the apple genome. Six homologs of SERK genes were identified between apple and Arabidopsis. Quantitative real-time PCR analyses revealed that the MdSERK genes showed different expression patterns in various tissues. Eight MdSERK genes were responsive to stress signals, such as methyl jasmonate, salicylic acid, abscisic acid, and salt (NaCl). The application of exogenous brassinosteroid and auxin increased the growth and endogenous hormone contents of Malus hupehensis seedlings. The expression levels of seven MdSERK genes were significantly upregulated by brassinosteroid and auxin. In addition, several MdSERK genes showed higher expression levels in standard trees of ‘Nagafu 2’ (CF)/CF than in dwarf trees of CF/‘Malling 9’ (M.9), and in CF than in the spur-type bud mutation “Yanfu 6” (YF).ConclusionThis study represents the first comprehensive investigation of the apple SERK gene family. These data indicate that apple SERKs may function in adaptation to adverse environmental conditions and may also play roles in controlling apple tree growth.

Identification of Serk Gene from Bract Derived Embryogenic and Non - Embryogenic Calli of Four Diploid Banana Cultivars from South India

Somatic embryogenesis receptor kinase (SERK) gene is known to be a marker of somatic embryogenesis in several plant species. The present study reported the presence of SERK gene from bract derived embryogenic calli bearing somatic embryos. The analysis of the expression pattern of the SERK gene during embryogenic cell formation and somatic embryogenesis revealed that SERK expression continued during pro embryogenic mass formation. In the present study the amplified product of cDNA from the somatic embryos has molecular size 1459 bp. The non- embryogenic callus also showed the presence of faint bands. In all the samples the amplified product from β - actin primer showed bands of 650 bp with similar intensity in both the embryogenic and non- embryogenic samples.

Expression analysis of three SERK-like genes in barley under abiotic and biotic stresses

ABSTRACTSomatic embryogenesis receptor-like kinases (SERKs), a subfamily of receptor-like kinases, showed important roles in plant response to abiotic and biotic stresses in addition to embryogenesis and organogenesis in numerous plant species. In the present study, three orthologs of SERK genes (HvSERK1/2/3) were isolated from barley, and their expression patterns during in vitro culture of microspores as well as their responses to different stresses including salinity and powdery mildew were characterized. Sequence analysis suggested that three HvSERK genes were highly conserved in the grass family. Subcellular localization showed the HvSERK1 protein located on the plasma membrane. The HvSERK1 transcript was up-regulated during the microspore culture period, suggesting its roles in microspore embryogenesis. HvSERK1 and HvSERK3 showed the highest expression level in the leaves; however no difference was detected for HvSERK2 expression in different plants’ tissues. Under salt stress, all three HvSERK genes were quickly induced in microspore-derived embryogenic calli, whereas only HvSERK1 was up-regulated in the roots of barley seedlings. Moreover, only HvSERK2 was induced in the barley leaves upon powdery mildew inoculation. These results suggest that barley SERK genes may participate in barley microspores’ development and plant response toward salt and fungal stress, and the function of them has some evolutionary changes.

Effects of 24-epibrassinolide and green light on plastid gene transcription and cytokinin content of barley leaves

In order to evaluate whether brassinosteroids (BS) and green light regulate the transcription of plastid genes in a cross-talk with cytokinins (CKs), transcription rates of 12 plastid genes (ndhF, rrn23, rpoB, psaA, psaB, rrn16, psbA, psbD, psbK, rbcL, atpB, and trnE/trnY) as well as the accumulation of transcripts of some photoreceptors (PHYA, CRY2, CRY1A, and CRY1B) and signaling (SERK and CAS) genes were followed in detached etiolated barley leaves exposed to darkness, green or white light ±1μm 24-epibrassinolide (EBL). EBL in the dark was shown to up-regulate the transcription of 12 plastid genes, while green light activated 10 genes and the EBL combined with the green light affected the transcription of only two genes (psaB and rpoB). Green light inhibited the expression of photoreceptor genes, except for CRY1A. Under the green light, EBL practically did not affect the expression of CRY1A, CAS and SERK genes, but it reduced the influence of white light on the accumulation of CAS, CRY1A, CRY1B, and SERK gene transcripts. The total content of BS in the dark and under white light remained largely unchanged, while under green light the total content of BRs (brassinolide, castasterone, and 6-deoxocastasterone) and HBRs (28-homobrassinolide, 28-homocastasterone, and 6-deoxo-28-homocastasterone) increased. The EBL-dependent up-regulation of plastome transcription in the dark was accompanied by a significant decrease in CK deactivation by O-glucosylation. However, no significant effect on the content of active CKs was detected. EBL combined with green light moderately increased the contents of trans-zeatin and isopentenyladenine, but had a negative effect on cis-zeatin. The most significant promotive effect of EBL on active CK bases was observed in white light. The data obtained suggest the involvement of CKs in the BS- and light-dependent transcription regulation of plastid genes.

Somatic embryogenesis receptor-like kinase 5 in the ecotype Landsberg erecta of Arabidopsis is a functional RD LRR-RLK in regulating brassinosteroid signaling and cell death control.

In plants, LRR-RLKs play central roles in regulating perception of extracellular signals and initiation of cellular responses under various environmental challenges. Arabidopsis SERK genes, including SERK1 to SERK5, constitute a LRR-RLK sub-family. SERK1, SERK2, SERK3/BAK1, and SERK4/BKK1 have been well characterized to function as crucial regulators in multiple physiological processes such as brassinosteroid signaling, cell death control, pathogenesis, and pollen development. Despite extremely high sequence identity with BKK1, SERK5 is reported to have no functional overlapping with BKK1, which is previously identified to regulate BR and cell death control pathways, probably due to a natural mutation in a highly conserved RD motif in the kinase domain of SERK5 in Col-0 ecotype. Through a gene sequencing analysis in several Arabidopsis accessions, we are able to identify SERK5 in Landsberg erecta (Ler) genome encoding a LRR-RLK with an intact RD motif. Overexpression of SERK5-Ler partially suppresses the BR defective phenotypes of bri1-5 and bak1-3 bkk1-1, indicating SERK5-Ler functions as a positive regulator in BR signaling. Furthermore, the interaction between SERK5-Ler and BRI1 is confirmed by yeast two-hybrid and BiFC assays, and the genetic result showing that elevated expression of a kinase-dead form of SERK5-Ler causes a dominant-negative phenotype in bri1-5. In addition, overexpression of SERK5-Ler is capable of delaying, not completely suppressing, the cell death phenotype of bak1-3 bkk1-1. In this study, we first reveal that SERK5-Ler is a biologically functional component in mediating multiple signaling pathways.

Gene expression and morphological characterization of cell suspensions of Coffea arabica L. cv. Catiguá MG2 in different cultivation stages

The present study aimed to evaluate the quality of cell suspension of Coffea arabica cv. Catigua at four different ages by morphological and gene expression analysis. For this purpose, cell suspension samples were collected at 30, 45, 60 and 75 days. Morphological analysis revealed the presence of embryogenic regions in all samples, and after 60 days, non-embryogenic regions were also identified. The genic analyses revealed that as the cells were transferred to a new medium a change in both their physical and chemical conditions was noticed that caused stress. The decrease in SERK and BBM genes expression after 75th day may also be due to the non-embryogenic regions, characterized by large, elongated and vacuolated cells that were observed in the periphery of embryogenic regions, starting from 60 days of culture.

Epigenetic regulation and gene markers as signals of early somatic embryogenesis

Identification and characterization of gene markers for somatic embryogenesis offer the possibility of determining the embryogenic potential of somatic cells before any morphological changes appear and to provide information on molecular regulation of early somatic embryogenesis. In this review, based on evidence reported in the literature, we assess the reliability of the established SERK, LEC and WUS marker genes as well as the usefulness of mediating epigenetic regulation by DNA methylation, chromatin remodeling and microRNAs as markers of the induction of somatic embryogenesis. The evidence suggests that the SERK gene marker may be less reliable than has been thought while the germin-like protein-encoding genes may, like their protein products, be useful markers of early somatic embryogenesis.

Characterization of the third SERK gene in pineapple (Ananas comosus) and analysis of its expression and autophosphorylation activity in vitro.

Two somatic embryogenesis receptor-like kinase genes (identified as AcSERK1 and AcSERK2) have previously been characterized from pineapple (Ananas comosus). In this work, we describe the characterization of a third gene (AcSERK3) in this family. AcSERK3 had all the characteristic domains and shared extensive sequence homology with other plant SERKs. AcSERK3 expression was studied by in situ hybridization and quantitative real-time PCR to analyze its function. Intense in situ hybridization signals were observed only in single competent cells and competent cell clusters; no hybridization signal was detected in the subsequent stages of somatic embryogenesis. AcSERK3 was highly expressed in embryogenic callus compared to other organs, e.g., 20-80 fold more than in anther but similar to that of non-embryogenic callus, which was 20-50 fold that of anther. AcSERK3 expression in root was 80 fold higher than in anther and the highest amongst all organs tested. These results indicate that AcSERK3 plays an important role in callus proliferation and root development. His-tagged AcSERK3 protein was successfully expressed and the luminescence of His6-AcSERK3 protein was only ∼5% of that of inactivated AcSERK3 protein and reaction buffer without protein, and 11.3% of that of an extract of host Escherichia coli pET-30a. This finding confirmed that the AcSERK3 fusion protein had autophosphorylation activity.

Molecular cloning and in silico analysis of three somatic embryogenesis receptor kinase mRNA from date palm

We report here the isolation and characterizations of three somatic embryogenesis receptor kinase (PhSERK) genes from palm date by a rapid amplification of cDNA ends (RACE) approach. PhSERKs belong to a small family of receptor kinase genes, share a conserved structure and extensive sequence homology with previously reported plant SERK genes. Sequence analysis of these genes revealed the sequence size of 11051 pb (PhSERK1), 7981 pb (PhSERK2) and 10510 pb (PhSERK3). The open reading frames of PhSERK1, PhSERK2 and PhSERK3 are 1914 pb, 1797 pb and 1719 pb respectively. PhSERKs belongs to the LRR-type cell surface RLKs, which possess a number of characteristic domains. These include an extracellular domain (EX) containing a variable number of LRR units, signal pepetide (SP) immediately followed by a single transmembrane domain (TM) and an intracellular kinase domain. The phylogenetic tree shows that the protein PhSERK1, PhSERK2 and PhSERK3 clustered within monocots SERKs proteins groups. We also predicted the secondary and tertiary with ligand binding sites structure of the protein PhSERKs.

Characterisation of the legume SERK-NIK gene superfamily including splice variants: implications for development and defence.

BackgroundSOMATIC EMBRYOGENESIS RECEPTOR-LIKE KINASE (SERK) genes are part of the regulation of diverse signalling events in plants. Current evidence shows SERK proteins function both in developmental and defence signalling pathways, which occur in response to both peptide and steroid ligands. SERKs are generally present as small gene families in plants, with five SERK genes in Arabidopsis. Knowledge gained primarily through work on Arabidopsis SERKs indicates that these proteins probably interact with a wide range of other receptor kinases and form a fundamental part of many essential signalling pathways. The SERK1 gene of the model legume, Medicago truncatula functions in somatic and zygotic embryogenesis, and during many phases of plant development, including nodule and lateral root formation. However, other SERK genes in M. truncatula and other legumes are largely unidentified and their functions unknown.ResultsTo aid the understanding of signalling pathways in M. truncatula, we have identified and annotated the SERK genes in this species. Using degenerate PCR and database mining, eight more SERK-like genes have been identified and these have been shown to be expressed. The amplification and sequencing of several different PCR products from one of these genes is consistent with the presence of splice variants. Four of the eight additional genes identified are upregulated in cultured leaf tissue grown on embryogenic medium. The sequence information obtained from M. truncatula was used to identify SERK family genes in the recently sequenced soybean (Glycine max) genome.ConclusionsA total of nine SERK or SERK-like genes have been identified in M. truncatula and potentially 17 in soybean. Five M. truncatula SERK genes arose from duplication events not evident in soybean and Lotus. The presence of splice variants has not been previously reported in a SERK gene. Upregulation of four newly identified SERK genes (in addition to the previously described MtSERK1) in embryogenic tissue cultures suggests these genes also play a role in the process of somatic embryogenesis. The phylogenetic relationship of members of the SERK gene family to closely related genes, and to development and defence function is discussed.

Somatic embryogenesis in the Panax ginseng cell culture induced by the rolC oncogene is associated with increased expression of WUS and SERK genes

The embryogenic cell culture 2c3 was previously obtained by the transfer of the rolC gene from Agrobacterium rhizogenes into ginseng callus cells. It was found by us that the expression of SERK and WUS genes in the embryogenic culture 2c3 is increased. These genes are known to be responsible for the initial stimulus to the development of embryogenesis in plants. Taking into consideration earlier data, we suppose that the development of somatic embryos in the ginseng cell culture 2c3 is associated with changes in the work of the calcium signaling system and with the activation of expression of SERK and WUS genes.

Structural Characterization and Expression Analysis of the SERK/SERL Gene Family in Rice (Oryza sativa)

Somatic embryogenesis (SE) is the developmental restructuring of somatic cells towards the embryogenic pathway and forms the basis of cellular totipotency in angiosperms. With the availability of full-length cDNA sequences from Knowledge-based Oryza Molecular Biological Encylopedia (KOME), we identified the leucine-rich repeat receptor-like kinase (LRR-RLK) genes from rice (Oryza sativa), which also encompasses genes involved in regulating somatic embryogenesis. Eight out of eleven of the rice SERK and SERL (SERK-like) genes have the TIGR annotation as (putative) brassinosteroid insensitive 1-associated receptor kinase (precursor). Real-time polymerase chain reaction analysis was undertaken to quantify transcript levels of these 11 genes. Most of these genes were upregulated by brassinosteroids although only a few of these displayed auxin induction. The expression profile of these genes is nearly uniform in the zygotic embryogenic tissue, but the expression pattern is more complex in the somatic embryogenic tissue. It is likely that OsSERKs and OsSERLs may be involved in somatic embryogenesis and also perform a role in morphogenesis and various other plant developmental processes. Functional validation of these somatic embryogenesis receptor-like kinase genes may help in elucidating their precise functions in regulating various facets of plant development.

Detection of a SERK-like gene in coconut and analysis of its expression during the formation of embryogenic callus and somatic embryos

Somatic embryogenesis involves different molecular events including differential gene expression and various signal transduction pathways. One of the genes identified in early somatic embryogenesis is S OMATIC E MBRYOGENESIS R ECEPTOR-like K INASE (SERK). Cocos nucifera (L.) is one of the most recalcitrant species for in vitro regeneration, achieved so far only through somatic embryogenesis, although just a few embryos could be obtained from a single explant. In order to increase efficiency of this process we need to understand it better. Therefore, the purpose of the present work was to determine if an ortholog of the SERK gene is present in the coconut genome, isolate it and analyze its expression during somatic embryogenesis. The results showed the occurrence of a SERK ortholog referred to as CnSERK. Predicted sequence analysis showed that CnSERK encodes a SERK protein with the domains reported in the SERK proteins in other species. These domains consist of a signal peptide, a leucine zipper domain, five LRR, the Serine-Proline-Proline domain, which is a distinctive domain of the SERK proteins, a single transmembrane domain, the kinase domain with 11 subdomains and the C terminal region. Analysis of its expression showed that it could be detected in embryogenic tissues before embryo development could be observed. In contrast it was not detected or at lower levels in non-embryogenic tissues, thus suggesting that CnSERK expression is associated with induction of somatic embryogenesis and that it could be a potential marker of cells competent to form somatic embryos in coconut tissues cultured in vitro.