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Expression level of Tilia amurensis genes involved in somatic embryogenesis. Colors represent row-scaled TMM-normalized TPM values.
Source publication
Tilia species are valuable woody species due to their beautiful shape and role as honey trees. Somatic embryogenesis can be an alternative method for mass propagation of T. amurensis. However, the molecular mechanisms of T. amurensis somatic embryogenesis are yet to be known. Here, we conducted comparative transcriptional analysis during somatic em...
Citations
... Wild germplasm resources of T. amurensis are in decline because its seeds show deep dormancy, which affects the maintenance of its natural populations [4,6]. This, coupled with its low reproductive efficiency and uneven seedling emergence, poses further challenges to the maintenance of germplasm resources [7]. Given the current shortage of T. amurensis seedlings, there is an urgent need to develop a rapid in vitro propagation system for T. amurensis to both address this shortage in the short term as well as preserve existing high-quality resources [6,8]. ...
Tilia amurensis is an economically valuable broadleaf tree species in Northeast China. The production of high-quality T. amurensis varieties at commercial scales has been greatly limited by the low germination rates. There is thus a pressing need to develop an organogenesis protocol for in vitro propagation of T. amurensis to alleviate a shortage of high-quality T. amurensis seedlings. Here, we established a rapid in vitro propagation system for T. amurensis from mature zygotic embryos and analyzed the effects of plant growth regulators and culture media in different stages. We found that Woody plant medium (WPM) was the optimal primary culture medium for mature zygotic embryos. The highest callus induction percentage (68.76%) and number of axillary buds induced (3.2) were obtained in WPM + 0.89 µmol/L 6-benzyladenine (6-BA) + 0.46 µmol/L kinetin (KT) + 0.25 µmol/L indole-3-butryic acid (IBA) + 1.44 µmol/L gibberellin A3 (GA3). The multiple shoot bud development achieved the highest percentage (83.32%) in the Murashige and Skoog (MS) + 2.22 µmol/L 6-BA + 0.25 µmol/L IBA + 1.44 µmol/L GA3. The rooting percentage (96.70%) was highest in 1/2 MS medium + 1.48 µmol/L IBA. The survival percentage of transplanting plantlets was 82.22% in soil:vermiculite:perlite (5:3:1). Our study is the first to establish an effective organogenesis protocol for T. amurensis using mature zygotic embryos.
... Concurrently, the emergence of high throughput transcriptome analysis is highly convenient as it provides a comprehensive gene expression profile of developmental stages to reveal the complex regulatory networks that spatially control cell fate. Recent studies have utilized transcriptome analysis to elucidate the molecular mechanisms of SE in Arabidopsis [16], rice [17], cotton [18], Tilia amurensis [19], Hevea brasiliensis [20] and coffee [21]. In previous study, difference of gene expression pattern in the induced primary calli, as well as re-differentiated roots were investigated during tissue culture of tea plant using transcriptomics only [22]. ...
Background
Darjeeling tea is a globally renowned beverage, which faces numerous obstacles in sexual reproduction, such as self-incompatibility, poor seed germination, and viability, as well as issues with vegetative propagation. Somatic embryogenesis (SE) is a valuable method for rapid clonal propagation of Darjeeling tea. However, the metabolic regulatory mechanisms underlying SE in Darjeeling tea remain largely unknown. To address this, we conducted an integrated metabolomics and transcriptomics analysis of embryogenic callus (EC), globular embryo (GE), and heart-shaped embryo (HE).
Results
The integrated analyses showed that various genes and metabolites involved in the phenylpropanoid pathway, auxin biosynthesis pathway, gibberellin, brassinosteroid and amino acids biosynthesis pathways were differentially enriched in EC, GE, and HE. Our results revealed that despite highly up-regulated auxin biosynthesis genes YUC1, TAR1 and AAO1 in EC, endogenous indole-3-acetic acid (IAA) was significantly lower in EC than GE and HE. However, bioactive Gibberellin A4 displayed higher accumulation in EC. We also found higher BABY BOOM (BBM) and Leafy cotyledon1 (LEC1) gene expression in GE along with high accumulation of castasterone, a brassinosteroid. Total flavonoids and phenolics levels were elevated in GE and HE compared to EC, especially the phenolic compound chlorogenic acid was highly accumulated in GE.
Conclusions
Integrated metabolome and transcriptome analysis revealed enriched metabolic pathways, including auxin biosynthesis and signal transduction, brassinosteroid, gibberellin, phenylpropanoid biosynthesis, amino acids metabolism, and transcription factors (TFs) during SE in Darjeeling tea. Notably, EC displayed lower endogenous IAA levels, conducive to maintaining differentiation, while higher IAA concentration in GE and HE was crucial for preserving embryo identity. Additionally, a negative correlation between bioactive gibberellin A4 (GA4) and IAA was observed, impacting callus growth in EC. The high accumulation of chlorogenic acid, a phenolic compound, might contribute to the low success rate in GE and HE formation in Darjeeling tea. TFs such as BBM1, LEC1, FUS3, LEA, WOX3, and WOX11 appeared to regulate gene expression, influencing SE in Darjeeling tea.
... SEs is one of the tools with the large-scale, efficient, rapid propagation, or doubled-haploids of elite genotypes and rare plant tools. SE acts as a model for studying the totipotency of somatic cells and for elucidating the somatic embryogenesis mechanisms of cellular and molecular in plants (Kang et al., 2021;Su et al., 2021;Yang et al., 2021;Ramírez-Mosqueda, 2022). Furthermore, SEs also used to study morpho-physiological, biochemical, and molecular processes in higher plants due to easy manipulation and controllable culture conditions (Gerdakaneh et al., 2021). ...
... Furthermore, SEs also used to study morpho-physiological, biochemical, and molecular processes in higher plants due to easy manipulation and controllable culture conditions (Gerdakaneh et al., 2021). Therefore, there is a significant application prospect in new variety breeding, producing artificial seeds, forest rapid propagation, totipotency analysis, and gene editing or transformation in SEs (Berengue et al., 2021;Kang et al., 2021;Yuan et al., 2022;Li et al., 2023). ...
... SERK1 expression controls by IAA and CK in M. truncatula embryogenic cultures [94]. SERK2 and SERK3 produce an IAA-specific response, while SERK1 and SERK5 interrelate with brassinosteroid (BRs) signaling [95]. SERK-like genes in C. nucifera were sequenced and are known as CnSERK. ...
The coconut palm (Cocos nucifera L.) is a perennial, cross-pollinated, oil-bearing tropical forest tree. Recently, the demand for coconut goods has surged to 5 to 10 times its former value; however, coconut production is in jeopardy. Coconut senility is one of the most apparent factors that influence productivity. Adequate replanting is urgently required to maintain the growing demand for coconut products. However, coconut palm mass replanting might not be possible with traditional approaches. To overcome this snag, micropropagation via somatic embryogenesis (SE) has enormous potential for proficient clonal propagation in the coconut palm. During SE, the stimulation of cell proliferation, acquisition of embryogenic cell competence, and induction of somatic embryos undergo a series of developmental events. This phenomenon requires regulation in gene expression patterns and the activation of specific signaling pathways. This review summarizes gene regulatory mechanisms involved in the cell cycle, dedifferentiation, totipotency, embryo initiation, and meristem development during somatic embryo formation. Plant hormonal signal transduction is also highlighted during the formation of SE in coconut.
... [59], Helianthus annuus L. [60], Ocotea catharinensis Mez. [61], Citrus unshiu Marcow [62], and Tilia amurensis [63]. In all these systems, SERK1 expression was linked to the formation of embryogenic tissue and embryogenic competence of the explants. ...
Somatic embryogenesis in Arabidopsis encompasses an induction phase requiring auxin as the inductive signal to promote cellular dedifferentiation and formation of the embryogenic tissue, and a developmental phase favoring the maturation of the embryos. Strigolactones (SLs) have been categorized as a novel group of plant hormones based on their ability to affect physiological phenomena in plants. The study analyzed the effects of synthetic strigolactone GR24, applied during the induction phase, on auxin response and formation of somatic embryos. The expression level of two SL biosynthetic genes, MOREAXILLARY GROWTH 3 and 4 (MAX3 and MAX4), which are responsible for the conversion of carotene to carotenal, increased during the induction phase of embryogenesis. Arabidopsis mutant studies indicated that the somatic embryo number was inhibited in max3 and max4 mutants, and this effect was reversed by applications of GR24, a synthetic strigolactone, and exacerbated by TIS108, a SL biosynthetic inhibitor. The transcriptional studies revealed that the regulation of GR24 and TIS108 on somatic embryogenesis correlated with changes in expression of AUXIN RESPONSIVE FACTORs 5, 8, 10, and 16, known to be required for the production of the embryogenic tissue, as well as the expression of WUSCHEL (WUS) and Somatic Embryogenesis Receptor-like Kinase 1 (SERK1), which are markers of cell dedifferentiation and embryogenic tissue formation. Collectively, this work demonstrated the novel role of SL in enhancing the embryogenic process in Arabidopsis and its requirement for inducing the expression of genes related to auxin signaling and production of embryogenic tissue.
... Although hormones play central roles in embryogenic callus induction, this non-genetic method of optimizing culture conditions cannot provide culture schemes suitable for all genotypes [8,9]. Recent evidence indicates that embryogenic callus forma-tion is a complex dynamic process that involves many intracellular metabolic changes and is influenced by various external environment factors [10,11]. ...
The plant embryogenic callus (EC) is an irregular embryogenic cell mass with strong regenerative ability that can be used for propagation and genetic transformation. However, difficulties with EC induction have hindered the breeding of drumstick, a tree with diverse potential commercial uses. In this study, three drumstick EC cDNA libraries were sequenced using an Illumina NovaSeq 6000 system. A total of 7191 differentially expressed genes (DEGs) for embryogenic callus development were identified, of which 2325 were mapped to the KEGG database, with the categories of plant hormone signal transduction and Plant-pathogen interaction being well-represented. The results obtained suggest that auxin and cytokinin metabolism and several embryogenesis-labeled genes are involved in embryogenic callus induction. Additionally, 589 transcription factors from 20 different families were differentially expressed during EC formation. The differential expression of 16 unigenes related to auxin signaling pathways was validated experimentally by quantitative real time PCR (qRT-PCR) using samples representing three sequential developmental stages of drumstick EC, supporting their apparent involvement in drumstick EC formation. Our study provides valuable information about the molecular mechanism of EC formation and has revealed new genes involved in this process.
Elevated CO2 and warmer temperatures represent the future environmental conditions in the context of global change. A good understanding of plant response to their combined effects is, therefore, critically important for predicting future plant performance. This study investigated the photosynthetic acclimation of amur linden (Tilia amurensis Rupr.) seedlings (current year, about 60 cm tall), a shade-tolerant tree species in the temperate broadleaf deciduous forest, to the combination of current CO2 concentration and temperature (CC) and the combination of the predicted future CO2 concentration and temperature (FC). The results show that FC promoted aboveground growth, but reduced photosynthetic capacity (Vcmax: maximum rate of RuBP carboxylation and Jmax: maximum photosynthetic electron transport rate). However, the photosynthetic rate measured under the corresponding growth CO2 concentration was still higher under FC than under CC. FC depressed the photosynthetic limiting transition point (Ci-t, An-t) from Rubisco carboxylation to RuBP regeneration, i.e., An-t decreased without a change in Ci-t. FC did not change leaf N concentration but increased the total leaf N content per tree and photosynthetic nitrogen utilization efficiency. This suggests that N utilization, rather than photosynthetic capacity, may play an important role in the acclimation of the species to future climatic conditions. This study provides new insights into the photosynthetic acclimation of amur linden and can be used to predict its possible performance under future climatic conditions.
At the molecular level, multicellular eukaryotic lineages and bacterial biofilms show predictable evolutionary footprints in their development. For instance, the zygotic embryogenesis of Arabidopsis , which is initiated by gamete fusion, shows hourglass-shaped ontogeny-phylogeny correlations at the transcriptome level. However, many plants are capable of yielding a fully viable next generation by somatic embryogenesis — a comparable developmental process that usually starts by the embryogenic induction of a diploid somatic cell. This leads to the question: is the hourglass-shaped ontogeny-phylogeny correlation preserved in somatic embryogenesis? To explore the correspondence between ontogeny and phylogeny in this alternative developmental route in plants, we developed a new and highly efficient model of somatic embryogenesis in grapevine ( Vitis vinifera ) and sequenced its developmental transcriptomes. By combining the evolutionary properties of grapevine genes with their expression values, which were recovered from early induction until the formation of juvenile plants, we found a strongly supported hourglass-shaped developmental trajectory. However, in contrast to zygotic embryogenesis in Arabidopsis where the torpedo stage was evolutionary the most inert, we found that in the somatic embryogenesis of grapevine the heart stage expressed evolutionary the oldest and the most conserved transcriptome. This is a surprising finding because it suggests a better evolutionary system-level analogy between animal development and plant somatic embryogenesis than zygotic embryogenesis. We conclude that macroevolutionary logic is deeply hardwired in plant ontogeny and that somatic embryogenesis is likely a primordial embryogenic program in plants.
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.
