Two SERK genes are markers of pluripotency in Cyclamen persicum Mill (original) (raw)
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Gene expression analyses during somatic embryogenesis in Cyclamen persicum
2019
Somatic embryogenesis (s.e.) enables a clonal propagation which is especially desirable for valuable crops. Particularly for plant species where clonal propagation by cuttings is not feasible, s.e. offers great potential for achieving mass propagation. This includes the economically important ornamental crop, Cyclamen persicum, that has been established as a model plant for s.e. In spite of its potential for encouraging high rates of propagation, the application of s.e. to commercial plant propagation is very low. This can be mainly attributed to the insufficient reproducibility of empirically developed propagation protocols as well as the restrictions imposed by the frequent occurrence of developmental aberrations and non-embryogenic callus. To date, it has been standard practice to change protocols empirically to improve the outcome. But the present approach pursued the idea of using the information obtained from gene expression profiling to better understand the underlying processes and thereby develop proposals on the targeted improvement of the existing protocol for in vitro s.e. For this purpose, putative underlying physiological processes were discussed and hypotheses on the improvement of the in vitro-protocol were deduced based on the data achieved by a cDNA microarray (1,216 transcripts). Selected hypotheses on the impact of putative glutathione S-transferases (GST) and pectin-modifying enzymes were analysed in more detail by qRT-PCR. Therefore, qRT-PCR protocol have been established and optimised for Cyclamen, especially with regard to the reference genes. Both validation approaches demonstrated that in their cases the initial hypothesis could not be supported. However, the approach involving putative GST homologues gave insights into the responsiveness of a putative GST homologue to abiotic stress in embryogenic cell cultures of Cyclamen and the study on putative genes of pectin modifying enzymes identified their correlation with the texture of the callus.
Somatic embryogenesis is crucial for the propagation of endangered Ecuadorian orchid species, among them Cyrtochilum loxense, in view of the fact that their number in nature or in collections is quite reduced. One of the genes expressed during somatic and zygotic embryogenesis is Somatic Embryogenesis Receptor-like Kinase (SERK). Despite the development of somatic embryogenesis protocols for orchids, no SERK genes have been isolated from this family. This is the first report on the isolation of a full-length orchid SERK sequence, namely that of Cyrtochilum loxense (ClSERK). The identity of ClSERK was inferred by the presence of all domains typical of SERK proteins: a signal peptide, a leucine zipper domain, five LRRs, a serine proline-rich domain, a transmembrane domain, a kinase domain, and the C-terminal region. We have observed that the ClSERK gene is highly expressed in embryogenic calluses generated from protocorms at the time of appearance of embryonic morphological features. At later stages when embryos become well visible on calluses, ClSERK gene expression decreases. Compared to early stages of embryo formation on calluses, the expression detected in leaf tissue is far lower, thus suggesting a role of this gene during development.
Plant Cell, Tissue and Organ Culture (PCTOC), 2014
Somatic embryogenesis receptor kinase (SERK) gene is known to be a marker of somatic embryogenesis in several plant species. The present study reported the isolation and characterization of a SERK gene ortholog, designated as McSERK, in Momordica charantia, an important medicinal plant. The complete coding region of McSERK was found to encode a 627 amino acid protein which contained an N-terminal signal peptide, a leucine zipper, five leucine rich repeats, a serine-proline-proline domain, a transmembrane domain, a kinase domain and the C-terminal region, depicting the typical characteristic features of SERK-family proteins. Phylogenetic analysis suggested that McSERK was highly similar to the SERK proteins of Cucumis sativus, Glycine max and Medicago truncatula. Homology modeling was attempted to construct the three dimensional structure of McSERK protein which showed that it corresponded to a monomeric protein.
3 BIOTECH, 2018
Somatic embryogenesis (SE) is one of the most important steps during regeneration, but the molecular mechanism of SE remains unclear for Cedrela odorata. SOMATIC EMBRYOGENESIS RECEPTOR-LIKE KINASE (SERK) is one of the genes associated with induction of SE and is considered a marker of cells competent to form somatic embryos. Our objective was to clone and characterize the SERK1 and SERK2 gene homologues and analyze their expression patterns during in vitro morphogenesis in Spanish cedar. CoSERK1 and CoSERK2 were isolated from cedar, both share domains characteristic of the SERK family, including leucine-rich repeats, a proline-rich motif, a transmembrane domain, and kinase domains. Embryo-genic cultures were established from callus cultures induced on medium supplemented with 1 mg/L dicamba. Histological sections were studied to determine the embryogenic nature of the samples. The CoSERK1 gene was highly expressed during the acquisition of embryogenic competence. The expression level of SERK1 was lower in non-embryogenic tissues and organs than in embryogenic calli, and it was higher in 3-week old embryogenic calli. CoSERK2 gene was highly expressed in leaves and shoots but no difference in expression was obtained between somatic and embryogenic tissues. These results suggest that the expression of CoSERK1 is associated with somatic embryogenesis induction and could be used as a potential marker to monitor the transition from competent to embryogenic cells and tissues in Spanish cedar.
Plant Molecular Biology Reporter, 2014
SOMATIC EMBRYOGENESIS RECEPTOR KINASE (SERK) genes are expressed primarily in seed plants and are involved in the development of embryos from alreadydifferentiated plant cells. This study provides the first evidence for the existence of a SERK gene, designated AcvSERK1, in a fern, Adiantum capillus-veneris. AcvSERK1 belongs to a small family of receptor-like kinases (RLKs), and its sequence and conserved structure closely resemble SERK homologs in other land plants. Phylogenetic analysis of the SERK gene family showed that AcvSERK1 forms a clade with SERK-like genes from non-seed plants and is a member of the SERK1/2 genes group, involved in somatic embryogenesis. Moreover, our analyses reveal that AcvSERK1 is expressed throughout the entire process of embryo development, but its levels decrease with the formation of shoots and seedlings. Additionally, in situ hybridization showed that AcvSERK1 is expressed during green globular body (GGB)-derived somatic embryogenesis and in meristematic calluses. Our results indicate that the AcvSERK1 gene is a good marker for differentiated cells that are capable of forming embryos in A. capillus-veneris, suggesting that SERK genes have played an important role in embryogenesis during the evolution of land plants.
Journal of Experimental Botany, 2009
SOMATIC EMBRYOGENESIS RECEPTOR-LIKE KINASE (SERK) genes have been demonstrated to play a role in somatic embryogenesis in several plant species. As more is learnt about these genes, the view of their role in plant development has broadened. The Medicago truncatula MtSERK1 gene has been associated with somatic embryogenesis and in vitro root formation. In order to study the role of MtSERK1 in development further, the MtSERK1 promoter sequence has been isolated and cloned into a promoter-GUS analysis vector. SERK1 promoterdriven GUS expression was studied in A. tumefaciens-transformed cultures and regenerated plants, in A. rhizogenes-transformed root clones, and in nodulation. In embryogenic cultures, GUS staining is detected after 2 d of culture at the edge of the explant and around vascular tissue. Expression at the explant edge intensifies over subsequent days and then is lost from the edge as callus formation moves inward. MtSERK1 expression appears to be associated with new callus formation. When somatic embryos form, GUS staining occurs throughout embryo development. Zygotic embryos show expression until the heart stage. The in planta studies reveal a number of interesting expression patterns. There appear to be three types. (i) Expression associated with the primary meristems of the root and shoot and the newly formed meristems of the lateral roots and nodule. (ii) Expression at the junction between one type of tissue or organ and another. (iii) Expression associated with the vascular tissue procambial cells. The data led us to conclude that MtSERK1 expression is associated with developmental change, possibly reflecting cellular reprogramming.
Protoplasma, 2015
The integration of cellular and molecular data is essential for understanding the mechanisms involved in the acquisition of competence by plant somatic cells and the cytological changes that underlie this process. In the present study, we investigated the dynamics and fate of Passiflora edulis Sims cotyledon explants that were committed to somatic embryogenesis by characterizing the associated ultrastructural events and analysing the expression of a putative P. edulis ortholog of the Somatic Embryogenesis Receptor-like Kinase (SERK) gene. Embryogenic calli were obtained from zygotic embryo explants cultured on Murashige and Skoog medium supplemented with 2,4-dichlorophenoxyacetic acid and 6-benzyladenine. Callus formation was initiated by the division of cells derived from the protodermal and subprotodermal cells on the abaxial side of the cotyledons. The isodiametric protodermal cells of the cotyledon explants adopted a columnar shape and became meristematic at the onset of PeSERK expression, which was not initially detected in explant cells. Therefore, we propose that these changes represent the first observable steps towards the acquisition of a competent state within this regeneration system. PeSERK expression was limited to the early stages of somatic embryogenesis; the expression of this gene was confined to proembryogenic zones and was absent in the embryos after the globular stage. Our data also demonstrated that the dynamics of the mobilization of reserve compounds correlated with the differentiation of the embryogenic callus.
Annals of botany, 2011
Understanding the fate and dynamics of cells during callus formation is essential to understanding totipotency and the mechanisms of somatic embryogenesis. Here, the fate of leaf explant cells during the development of embryogenic callus was investigated in the model legume Medicago truncatula. Callus development was examined from cultured leaf explants of the highly regenerable genotype Jemalong 2HA (2HA) and from mesophyll protoplasts of 2HA and wild-type Jemalong. Callus development was studied by histology, manipulation of the culture system, detection of early production of reactive oxygen species and visualization of SERK1 (SOMATIC EMBRYO RECEPTOR KINASE1) gene expression. Callus formation in leaf explants initiates at the cut surface and within veins of the explant. The ontogeny of callus development is dominated by the division and differentiation of cells derived from pluripotent procambial cells and from dedifferentiated mesophyll cells. Procambium-derived cells differenti...
Signaling Overview of Plant Somatic Embryogenesis
Frontiers in Plant Science
Somatic embryogenesis (SE) is a means by which plants can regenerate bipolar structures from a somatic cell. During the process of cell differentiation, the explant responds to endogenous stimuli, which trigger the induction of a signaling response and, consequently, modify the gene program of the cell. SE is probably the most studied plant regeneration model, but to date it is the least understood due to the unclear mechanisms that occur at a cellular level. In this review, the authors seek to emphasize the importance of signaling on plant SE, highlighting the interactions between the different plant growth regulators (PGR), mainly auxins, cytokinins (CKs), ethylene and abscisic acid (ABA), during the induction of SE. The role of signaling is examined from the start of cell differentiation through the early steps on the embryogenic pathway, as well as its relation to a plant's tolerance of different types of stress. Furthermore, the role of genes encoded to transcription factors (TFs) during the embryogenic process such as the LEAFY COTYLEDON (LEC), WUSCHEL (WUS), BABY BOOM (BBM) and CLAVATA (CLV) genes, Arabinogalactan-proteins (AGPs), APETALA 2 (AP2) and epigenetic factors is discussed.