Somatic embryos of Ocotea catharinensis were used as a model to investigate the biosynthetic path... more Somatic embryos of Ocotea catharinensis were used as a model to investigate the biosynthetic pathway of tetrahydrobenzofuran neolignan formation by means of feeding 13 C-labelled precursors followed by analysis using MS and 13 C NMR. Isotopomers of L-[ 13 C]-phenylalanine administered to embryos were incorporated into tetrahydrobenzofuran neolignans and the analysis of 13 C NMR clearly revealed the enriched position of precursors. While feeding a series of putative intermediate including [8-13 C]-ferulic acid, [8-13 C]-glycoferulic acid, and [8-13 C]-coniferyl alcohol were not successful in incorporation to the neolignans, the [8-13 C]-coniferyl acetate was detected as an intermediate in the biosynthesis of the neolignan 5'-methoxy-porosin. In the bioconversion assay using the protein fraction from the embryogenic cultures, only the substrate coniferyl acetate was converted into isoeugenol, which together with eugenol, is one of the putative precursors of neolignan formation. These findings support that the tetrahydrobenzofuran neolignans are derived from the oxidative coupling between units of E-isoeugenol and 5'-methoxy-eugenol leading to a regio-and stereospecific products.
The secondary metabolism of Piper species is known to produce a myriad of natural products from v... more The secondary metabolism of Piper species is known to produce a myriad of natural products from various biosynthetic pathways which, represent a rich source of previously uncharacterized chemical compounds. The determination of gene expression profiles in multiple tissue/organ samples could provide valuable clues towards understanding the potential biological functions of chemical changes in these plants. Studies on gene expression by RT-qPCR require particularly careful selection of suitable reference genes as a control for normalization. Here, we provide a study for the identification of reliable reference genes in P. arboreum, P. gaudichaudianum, P. malacophyllum, and P. tuberculatum, at two different life stages: 2-month-old seedlings and adult plants. To do this, annotated sequences were recovered from transcriptome datasets of the above listed Piper spp. These sequences were subjected to expression analysis using RT-qPCR, followed by analysis using the geNorm and NormFinder algorithms. A set of five genes were identified showing stable expression: ACT7 (Actin-7), Cyclophilin (Peptidyl-prolyl cis-trans isomerase), EF1α (Elongation factor 1-alpha), RNABP (RNA-binding protein), and UBCE (Ubiquitin conjugating enzyme). The universality of these genes was then validated using two target genes, ADC (arginine decarboxylase) and SAMDC (S-adenosylmethionine decarboxylase), which are involved in the biosynthesis of polyamines. We showed that normalization genes varied according to Piper spp., and we provide a list of recommended pairs of the best combination for each species. This study provides the first set of suitable candidate genes for gene expression studies in the four Piper spp. assayed, and the findings will facilitate subsequent transcriptomic and functional gene research.
Plant expansins are enzymes that act in a pH-dependent manner in the plant cell wall loosening an... more Plant expansins are enzymes that act in a pH-dependent manner in the plant cell wall loosening and are associated with improved tolerance or resistance to abiotic or biotic stresses. Plant-parasitic nematodes (PPN) can alter the expression profle of several expansin genes in infected root cells. Studies have shown that overexpression or downregulation of particular expansin genes can reduce plant susceptibility to PPNs. Root-knot nematodes (RKN) are obligate sedentary endoparasites of the genus Meloidogyne spp. of which M. incognita is one of the most reported species. Herein, using a transcriptome dataset and real-time PCR assays were identifed an expansin A gene (GmEXPA1; Glyma.02G109100) that is upregulated in the soybean nematode-resistant genotype PI595099 compared to the susceptible cultivar BRS133 during plant parasitism by M. incognita. To understand the role of the GmEXPA1 gene during the interaction between soybean plant and M. incognita were generated stable A. thaliana and N. tabacum transgenic lines. Remarkably, both A. thaliana and N. tabacum transgenic lines overexpressing the GmEXPA1 gene showed reduced susceptibility to M. incognita. Furthermore, plant growth, biomass accumulation, and seed yield were not afected in these transgenic lines. Interestingly, signifcant upregulation of the NtACC oxidase and NtEFE26 genes, involved in ethylene biosynthesis, and NtCCR and Nt4CL genes, involved in lignin biosynthesis, was observed in roots of the N. tabacum transgenic lines, which also showed higher lignin content. These data suggested a possible link between GmEXPA1 gene expression and increased lignifcation of the root cell wall. Therefore, these data support that engineering of the GmEXPA1 gene in soybean ofers a powerful biotechnology tool to assist in RKN management.
Many studies in the model species Arabidopsis thaliana characterized genes involved in embryo for... more Many studies in the model species Arabidopsis thaliana characterized genes involved in embryo formation. However, much remains to be learned about the portfolio of genes that are involved in signal transduction and transcriptional regulation during plant embryo development in other species, particularly in an evolutionary context; especially considering that some genes involved in embryo patterning are not exclusive of land plants. In this study, we used a combination of domain architecture phylostratigraphy and phylogenetic reconstruction to investigate the evolutionary history of embryo patterning and auxin metabolism (EPAM) genes in Viridiplantae. This approach shed light on the co-optation of auxin metabolism and other molecular mechanisms that contributed to the radiation of land plants, and specifically to embryo formation. These results have potential to assist conservation programs, by directing the development of tools for obtaining somatic embryos. In this context, we employed this methodology with critically endangered and non-model species Araucaria angustifolia, the Brazilian pine, which is current focus of conservation efforts using somatic embryogenesis. So far, this approach had little success since somatic embryos fail to completely develop. By profiling the expression of genes that we identified as necessary for the emergence of land-plant embryos, we found striking differences between zygotic and somatic embryos that might explain the developmental arrest and be used to improve A. angustifolia somatic culture.
Abstract Araucaria angustifolia is classified as a critically endangered species by the Internati... more Abstract Araucaria angustifolia is classified as a critically endangered species by the International Union for Conservation of Nature. This threat is worsened by the inefficiency of methods for ex-situ conservation and propagation. In conifers, somatic embryogenesis (SE) associated with cryopreservation is an efficient method to achieve germplasm conservation and mass clonal propagation. However, the efficiency of SE is highly dependent on genotype responsivity to the artificial stimulus used in vitro during cell line proliferation and later during somatic embryo development. In this study, we evaluated the activity of antioxidant enzymes and characterized mitochondrial functions during the proliferation of embryogenic cells of A. angustifolia responsive (SE1) and non-responsive (SE6) to the development of somatic embryos. The activities of the antioxidant enzymes GR (EC 1.6.4.2), MDHAR (EC 1.6.5.4), and POX (EC 1.11.1.7) were increased in SE1 culture, while in SE6 culture, only the activity of DHAR (EC 1.8.5.1) was significantly higher. Additionally, SE6 culture presented a higher number of mitochondria, which agreed with the increased rate of oxygen consumption compared to responsive SE1 culture; however, the mitochondrial volume was lower. Although the ATP levels did not differ, the NAD(P)H levels were higher in SE1 cells. NDs, AOX, and UCP were less active in responsive SE1 than in non-responsive cells. Our results show significant differences between SE1 and SE6 embryogenic cells regarding mitochondrial functions and antioxidant enzyme activities, which may be intrinsic to the in vitro proliferation phase of both cell lines, possessing a crucial role for the induction of in vitro maturation process.
Key message Analysis of polyamines and amino acid profiles in Araucaria angustifolia immature see... more Key message Analysis of polyamines and amino acid profiles in Araucaria angustifolia immature seeds from two mother tree genotypes in 2 consecutive years, and their association with the establishment of embryogenic cultures. Abstract Polyamines (PAs) and amino acids are an important source of nitrogen in plants. They are known to participate in plant development and their levels are associated with specific zygotic and somatic embryogenesis stages, which means that they may be useful as biochemical markers of developmental stages. The present study carried out an analysis of PA and amino acid profiles in immature Araucaria angustifolia seeds from two mother tree genotypes over 2 consecutive years, and their association with the initiation and maintenance of embryogenic cultures (ECs). The results showed that initiation of ECs in A. angustifolia, as observed in other conifers, depends on harvest year and mother tree genotype. PA and amino acid profiles showed that seeds from distinct mother trees and harvest years are different from one another. These differences were reflected in the initiation of ECs. The metabolic analysis indicates that conjugated Spd, ornithine, and asparagine profiles are candidates as biochemical markers for selection of mother trees. These results will allow for the testing of a large number of mother trees as explant sources and the selection of those with higher potential for somatic embryogenesis.
Araucaria angustifolia (Bertol.) O. Kuntze exhibits dimorphism in its stem structure, where the t... more Araucaria angustifolia (Bertol.) O. Kuntze exhibits dimorphism in its stem structure, where the trunk is orthotropic and branches and branchlets (primary and secondary branches) are plagiotropic. These stems exhibit different behavior when used for vegetative propagation, and only segments of trunk can form a complete plant. The physiological and biochemical mechanisms that characterize these stems are still little known. The aim of this study was to describe the free amino acid profiles in trunks, branches, and branchlets of A. angustifolia. Segments of 5 cm in length were excised from young individuals below the stem apex. The needles were removed and samples were frozen and lyophilized. The determinations were made by high-performance liquid chromatography, and the results were expressed as lg/g fresh weight (FW). The trunks and branches had the highest content of total amino acids, which were 112.23 ± 20.57 lg/g FW and 111.97 ± 27.78 lg/g FW, respectively. The amino acidsglutamine, aspartate and c-aminobutyric acid and tyrosine-were noticeably higher in the three types of stems. In the trunk, a higher amount of asparagine and tryptophan, was also detected. Glutamic acid and glutamine were found in higher quantities in the branches. The branchlets had very low total amino acid content (30.79 ± 4.19 lg/g FW), wherein asparagine is the only amino acid not detected. Thus, it was observed that the profile of the free amino acid differs among trunks, branches, and branchlets in A. angustifolia, indicating that they perform different functions.
pathway played by salicylic acid, gentisic acid, nitric oxide, polyamines and non-enzymatic antio... more pathway played by salicylic acid, gentisic acid, nitric oxide, polyamines and non-enzymatic antioxidants in compatible and incompatible Solanum-tomato mottle mosaic virus interactions,
The in vitro effect of cadmium (Cd) on apical segments of the red macroalga Pterocladiella capill... more The in vitro effect of cadmium (Cd) on apical segments of the red macroalga Pterocladiella capillacea was examined. Over a period of 7 days, the segments were cultivated with a combination of different salinities (25, 35, and 45 psu) and Cd concentrations ranging from 0.17 to 0.70 ppm. This study aimed to evaluate the effects of Cd exposure at various salinities on profiles of carotenoids amino acids and phenolic compounds. Carotenoid profile of control (0 ppm Cd) and Cdtreated plants of P. capillacea showed the presence of lutein, zeaxanthin, β-cryptoxanthin, α-carotene, trans-β-carotene and cis-β-carotene. Significant increase was found for almost all carotenoids, 0.35 ppm Cd + 25 psu, 0.70 ppm Cd + 25 psu, and 0 ppm Cd + 45 psu. Total phenolic compounds of P. capillacea had an overall decrease with treatments of Cd and 25 or 45 psu. Twenty essential amino acids were quantified in P. capillacea samples. At 0 ppm Cd and using baseline control of 35 psu, low and high salinity levels (25 and 45 psu, respectively) significantly altered total amino acid content. Apparently, salinity plays a greater role in amino acid response than Cd concentration. Therefore, more studies with intensified salinity stress over long-term exposure could confirm the major effect of the suggested treatment on this species.
Somatic embryogenesis occurs through complex processes modulated by gene regulatory networks at a... more Somatic embryogenesis occurs through complex processes modulated by gene regulatory networks at an appropriate spatiotemporal scale important for cell division and differentiation. Post-transcription regulation mechanisms mediated by miRNAs control the expression of several genes involved in embryogenesis. Transcript and proteomics studies in embryogenic cultures from Araucaria angustifolia, an endangered native Brazilian conifer with ecological and economic importance, have indicated a role for posttranscriptional regulation in this process. One example is the differential abundance of ARGONAUTE between two contrasting embryogenic cell lines. Here, we pro led the miRNA expression pattern in two cell lines of A. angustifolia with distinct embryogenic potential using small RNA sequencing technology. We identi ed 165 mature miRNAs, of which 143 were novel and 22 were conserved plant miRNAs. Seven miRNA conserved families were identi ed: miR156, miR169, miR394, miR482, miR536, miR1030, and miR1314. Most miRNAs were differentially expressed during the transition from proliferation to the maturation stage of somatic embryogenesis, suggesting that miRNAs play more important roles in the early somatic embryo development. A total of 98 potential target genes were found for 89 miRNAs, involved in post-transcriptional processes, transporters, defense response, sugar regulation, stress, ABA controlling and signaling, cell-to-cell communication, maintaining suspensor cell identity, brassinosteroids signaling, and cell division. Negative correlations of expression patterns between miRNAs and their targets were detected for miR1030-PRL1, miR1314-ADR1-Like, and Aang34-LRR modules, when analyzed by RT-qPCR. Taken together, our ndings provide new insights into the regulatory roles of miRNAs and their target genes in the somatic embryogenesis of Brazilian pine. including miRNAs and small interfering RNA (siRNAs) (Lakhwani et al. 2020). miRNAs are a distinct class of single-stranded RNA of ~ 18-25 nucleotides (Zhang et al. 2018a,b; Lin et al. 2020). MIR genes are endogenously transcribed as long precursor transcripts (pri-miRNAs), forming a fold-back hairpin structure with the small RNA embedded in one of its arms (Rogers and Chen 2013; Chorostecki et al. 2017). MiRNAs play a key role in post-transcriptional regulation or repression of translation mechanisms (Tiwari et al. 2020). The mature miRNAs negatively regulate gene expression by binding to the partially complementary sequences in the target messenger RNAs (mRNAs), in their opening reading frame (ORF) or UTR regions of speci c target genes (Zhang et al. 2018a; Liu et al. 2019). Then, cleavage and degradation of mRNA molecules or inhibition of translation are carried out with the cooperation of RISC (Liu et al. 2019). Over hundreds miRNA targets seem to be expressed in the developing embryo underlining the relevant role of miRNAs in embryogenesis (Alves et al. 2020; Jeena et al. 2022). Identifying the miRNAs that regulate somatic embryogenesis extends our knowledge about the regulatory pathways controlling embryogenic transitions (Wójcik et al. 2017; Juárez-González et al. 2019; Siddiqui et al. 2019), with implications for control of cell-speci c gene expression programs according to both spatial and temporal cues (Plotnikova et al. 2019). The proper patterning and morphology of embryos are related to the expression of miRNAs and their
Plant lignocellulosic biomass, mostly composed of polysaccharide-rich secondary cell walls (SCWs)... more Plant lignocellulosic biomass, mostly composed of polysaccharide-rich secondary cell walls (SCWs), provides fermentable sugars that may be used to produce biofuels and biomaterials. However, the complex chemical composition and physical structure of SCWs hinder efficient processing of plant biomass. Understanding the molecular mechanisms underlying SCW deposition is, thus, essential to optimize bioenergy feedstocks. Here, we establish a xylogenic culture as a model system to study SCW deposition in sugarcane; the first of its kind in a C4 grass species. We used auxin and brassinolide to differentiate sugarcane suspension cells into tracheary elements, which showed metaxylem-like reticulate or pitted SCW patterning. The differentiation led to increased lignin levels, mainly caused by S-lignin units, and a rise in p-coumarate, leading to increased p-coumarate:ferulate ratios. RNAseq analysis revealed massive transcriptional reprogramming during differentiation, with upregulation of ge...
Somatic embryos of Ocotea catharinensis were used as a model to investigate the biosynthetic path... more Somatic embryos of Ocotea catharinensis were used as a model to investigate the biosynthetic pathway of tetrahydrobenzofuran neolignan formation by means of feeding 13 C-labelled precursors followed by analysis using MS and 13 C NMR. Isotopomers of L-[ 13 C]-phenylalanine administered to embryos were incorporated into tetrahydrobenzofuran neolignans and the analysis of 13 C NMR clearly revealed the enriched position of precursors. While feeding a series of putative intermediate including [8-13 C]-ferulic acid, [8-13 C]-glycoferulic acid, and [8-13 C]-coniferyl alcohol were not successful in incorporation to the neolignans, the [8-13 C]-coniferyl acetate was detected as an intermediate in the biosynthesis of the neolignan 5'-methoxy-porosin. In the bioconversion assay using the protein fraction from the embryogenic cultures, only the substrate coniferyl acetate was converted into isoeugenol, which together with eugenol, is one of the putative precursors of neolignan formation. These findings support that the tetrahydrobenzofuran neolignans are derived from the oxidative coupling between units of E-isoeugenol and 5'-methoxy-eugenol leading to a regio-and stereospecific products.
The secondary metabolism of Piper species is known to produce a myriad of natural products from v... more The secondary metabolism of Piper species is known to produce a myriad of natural products from various biosynthetic pathways which, represent a rich source of previously uncharacterized chemical compounds. The determination of gene expression profiles in multiple tissue/organ samples could provide valuable clues towards understanding the potential biological functions of chemical changes in these plants. Studies on gene expression by RT-qPCR require particularly careful selection of suitable reference genes as a control for normalization. Here, we provide a study for the identification of reliable reference genes in P. arboreum, P. gaudichaudianum, P. malacophyllum, and P. tuberculatum, at two different life stages: 2-month-old seedlings and adult plants. To do this, annotated sequences were recovered from transcriptome datasets of the above listed Piper spp. These sequences were subjected to expression analysis using RT-qPCR, followed by analysis using the geNorm and NormFinder algorithms. A set of five genes were identified showing stable expression: ACT7 (Actin-7), Cyclophilin (Peptidyl-prolyl cis-trans isomerase), EF1α (Elongation factor 1-alpha), RNABP (RNA-binding protein), and UBCE (Ubiquitin conjugating enzyme). The universality of these genes was then validated using two target genes, ADC (arginine decarboxylase) and SAMDC (S-adenosylmethionine decarboxylase), which are involved in the biosynthesis of polyamines. We showed that normalization genes varied according to Piper spp., and we provide a list of recommended pairs of the best combination for each species. This study provides the first set of suitable candidate genes for gene expression studies in the four Piper spp. assayed, and the findings will facilitate subsequent transcriptomic and functional gene research.
Plant expansins are enzymes that act in a pH-dependent manner in the plant cell wall loosening an... more Plant expansins are enzymes that act in a pH-dependent manner in the plant cell wall loosening and are associated with improved tolerance or resistance to abiotic or biotic stresses. Plant-parasitic nematodes (PPN) can alter the expression profle of several expansin genes in infected root cells. Studies have shown that overexpression or downregulation of particular expansin genes can reduce plant susceptibility to PPNs. Root-knot nematodes (RKN) are obligate sedentary endoparasites of the genus Meloidogyne spp. of which M. incognita is one of the most reported species. Herein, using a transcriptome dataset and real-time PCR assays were identifed an expansin A gene (GmEXPA1; Glyma.02G109100) that is upregulated in the soybean nematode-resistant genotype PI595099 compared to the susceptible cultivar BRS133 during plant parasitism by M. incognita. To understand the role of the GmEXPA1 gene during the interaction between soybean plant and M. incognita were generated stable A. thaliana and N. tabacum transgenic lines. Remarkably, both A. thaliana and N. tabacum transgenic lines overexpressing the GmEXPA1 gene showed reduced susceptibility to M. incognita. Furthermore, plant growth, biomass accumulation, and seed yield were not afected in these transgenic lines. Interestingly, signifcant upregulation of the NtACC oxidase and NtEFE26 genes, involved in ethylene biosynthesis, and NtCCR and Nt4CL genes, involved in lignin biosynthesis, was observed in roots of the N. tabacum transgenic lines, which also showed higher lignin content. These data suggested a possible link between GmEXPA1 gene expression and increased lignifcation of the root cell wall. Therefore, these data support that engineering of the GmEXPA1 gene in soybean ofers a powerful biotechnology tool to assist in RKN management.
Many studies in the model species Arabidopsis thaliana characterized genes involved in embryo for... more Many studies in the model species Arabidopsis thaliana characterized genes involved in embryo formation. However, much remains to be learned about the portfolio of genes that are involved in signal transduction and transcriptional regulation during plant embryo development in other species, particularly in an evolutionary context; especially considering that some genes involved in embryo patterning are not exclusive of land plants. In this study, we used a combination of domain architecture phylostratigraphy and phylogenetic reconstruction to investigate the evolutionary history of embryo patterning and auxin metabolism (EPAM) genes in Viridiplantae. This approach shed light on the co-optation of auxin metabolism and other molecular mechanisms that contributed to the radiation of land plants, and specifically to embryo formation. These results have potential to assist conservation programs, by directing the development of tools for obtaining somatic embryos. In this context, we employed this methodology with critically endangered and non-model species Araucaria angustifolia, the Brazilian pine, which is current focus of conservation efforts using somatic embryogenesis. So far, this approach had little success since somatic embryos fail to completely develop. By profiling the expression of genes that we identified as necessary for the emergence of land-plant embryos, we found striking differences between zygotic and somatic embryos that might explain the developmental arrest and be used to improve A. angustifolia somatic culture.
Abstract Araucaria angustifolia is classified as a critically endangered species by the Internati... more Abstract Araucaria angustifolia is classified as a critically endangered species by the International Union for Conservation of Nature. This threat is worsened by the inefficiency of methods for ex-situ conservation and propagation. In conifers, somatic embryogenesis (SE) associated with cryopreservation is an efficient method to achieve germplasm conservation and mass clonal propagation. However, the efficiency of SE is highly dependent on genotype responsivity to the artificial stimulus used in vitro during cell line proliferation and later during somatic embryo development. In this study, we evaluated the activity of antioxidant enzymes and characterized mitochondrial functions during the proliferation of embryogenic cells of A. angustifolia responsive (SE1) and non-responsive (SE6) to the development of somatic embryos. The activities of the antioxidant enzymes GR (EC 1.6.4.2), MDHAR (EC 1.6.5.4), and POX (EC 1.11.1.7) were increased in SE1 culture, while in SE6 culture, only the activity of DHAR (EC 1.8.5.1) was significantly higher. Additionally, SE6 culture presented a higher number of mitochondria, which agreed with the increased rate of oxygen consumption compared to responsive SE1 culture; however, the mitochondrial volume was lower. Although the ATP levels did not differ, the NAD(P)H levels were higher in SE1 cells. NDs, AOX, and UCP were less active in responsive SE1 than in non-responsive cells. Our results show significant differences between SE1 and SE6 embryogenic cells regarding mitochondrial functions and antioxidant enzyme activities, which may be intrinsic to the in vitro proliferation phase of both cell lines, possessing a crucial role for the induction of in vitro maturation process.
Key message Analysis of polyamines and amino acid profiles in Araucaria angustifolia immature see... more Key message Analysis of polyamines and amino acid profiles in Araucaria angustifolia immature seeds from two mother tree genotypes in 2 consecutive years, and their association with the establishment of embryogenic cultures. Abstract Polyamines (PAs) and amino acids are an important source of nitrogen in plants. They are known to participate in plant development and their levels are associated with specific zygotic and somatic embryogenesis stages, which means that they may be useful as biochemical markers of developmental stages. The present study carried out an analysis of PA and amino acid profiles in immature Araucaria angustifolia seeds from two mother tree genotypes over 2 consecutive years, and their association with the initiation and maintenance of embryogenic cultures (ECs). The results showed that initiation of ECs in A. angustifolia, as observed in other conifers, depends on harvest year and mother tree genotype. PA and amino acid profiles showed that seeds from distinct mother trees and harvest years are different from one another. These differences were reflected in the initiation of ECs. The metabolic analysis indicates that conjugated Spd, ornithine, and asparagine profiles are candidates as biochemical markers for selection of mother trees. These results will allow for the testing of a large number of mother trees as explant sources and the selection of those with higher potential for somatic embryogenesis.
Araucaria angustifolia (Bertol.) O. Kuntze exhibits dimorphism in its stem structure, where the t... more Araucaria angustifolia (Bertol.) O. Kuntze exhibits dimorphism in its stem structure, where the trunk is orthotropic and branches and branchlets (primary and secondary branches) are plagiotropic. These stems exhibit different behavior when used for vegetative propagation, and only segments of trunk can form a complete plant. The physiological and biochemical mechanisms that characterize these stems are still little known. The aim of this study was to describe the free amino acid profiles in trunks, branches, and branchlets of A. angustifolia. Segments of 5 cm in length were excised from young individuals below the stem apex. The needles were removed and samples were frozen and lyophilized. The determinations were made by high-performance liquid chromatography, and the results were expressed as lg/g fresh weight (FW). The trunks and branches had the highest content of total amino acids, which were 112.23 ± 20.57 lg/g FW and 111.97 ± 27.78 lg/g FW, respectively. The amino acidsglutamine, aspartate and c-aminobutyric acid and tyrosine-were noticeably higher in the three types of stems. In the trunk, a higher amount of asparagine and tryptophan, was also detected. Glutamic acid and glutamine were found in higher quantities in the branches. The branchlets had very low total amino acid content (30.79 ± 4.19 lg/g FW), wherein asparagine is the only amino acid not detected. Thus, it was observed that the profile of the free amino acid differs among trunks, branches, and branchlets in A. angustifolia, indicating that they perform different functions.
pathway played by salicylic acid, gentisic acid, nitric oxide, polyamines and non-enzymatic antio... more pathway played by salicylic acid, gentisic acid, nitric oxide, polyamines and non-enzymatic antioxidants in compatible and incompatible Solanum-tomato mottle mosaic virus interactions,
The in vitro effect of cadmium (Cd) on apical segments of the red macroalga Pterocladiella capill... more The in vitro effect of cadmium (Cd) on apical segments of the red macroalga Pterocladiella capillacea was examined. Over a period of 7 days, the segments were cultivated with a combination of different salinities (25, 35, and 45 psu) and Cd concentrations ranging from 0.17 to 0.70 ppm. This study aimed to evaluate the effects of Cd exposure at various salinities on profiles of carotenoids amino acids and phenolic compounds. Carotenoid profile of control (0 ppm Cd) and Cdtreated plants of P. capillacea showed the presence of lutein, zeaxanthin, β-cryptoxanthin, α-carotene, trans-β-carotene and cis-β-carotene. Significant increase was found for almost all carotenoids, 0.35 ppm Cd + 25 psu, 0.70 ppm Cd + 25 psu, and 0 ppm Cd + 45 psu. Total phenolic compounds of P. capillacea had an overall decrease with treatments of Cd and 25 or 45 psu. Twenty essential amino acids were quantified in P. capillacea samples. At 0 ppm Cd and using baseline control of 35 psu, low and high salinity levels (25 and 45 psu, respectively) significantly altered total amino acid content. Apparently, salinity plays a greater role in amino acid response than Cd concentration. Therefore, more studies with intensified salinity stress over long-term exposure could confirm the major effect of the suggested treatment on this species.
Somatic embryogenesis occurs through complex processes modulated by gene regulatory networks at a... more Somatic embryogenesis occurs through complex processes modulated by gene regulatory networks at an appropriate spatiotemporal scale important for cell division and differentiation. Post-transcription regulation mechanisms mediated by miRNAs control the expression of several genes involved in embryogenesis. Transcript and proteomics studies in embryogenic cultures from Araucaria angustifolia, an endangered native Brazilian conifer with ecological and economic importance, have indicated a role for posttranscriptional regulation in this process. One example is the differential abundance of ARGONAUTE between two contrasting embryogenic cell lines. Here, we pro led the miRNA expression pattern in two cell lines of A. angustifolia with distinct embryogenic potential using small RNA sequencing technology. We identi ed 165 mature miRNAs, of which 143 were novel and 22 were conserved plant miRNAs. Seven miRNA conserved families were identi ed: miR156, miR169, miR394, miR482, miR536, miR1030, and miR1314. Most miRNAs were differentially expressed during the transition from proliferation to the maturation stage of somatic embryogenesis, suggesting that miRNAs play more important roles in the early somatic embryo development. A total of 98 potential target genes were found for 89 miRNAs, involved in post-transcriptional processes, transporters, defense response, sugar regulation, stress, ABA controlling and signaling, cell-to-cell communication, maintaining suspensor cell identity, brassinosteroids signaling, and cell division. Negative correlations of expression patterns between miRNAs and their targets were detected for miR1030-PRL1, miR1314-ADR1-Like, and Aang34-LRR modules, when analyzed by RT-qPCR. Taken together, our ndings provide new insights into the regulatory roles of miRNAs and their target genes in the somatic embryogenesis of Brazilian pine. including miRNAs and small interfering RNA (siRNAs) (Lakhwani et al. 2020). miRNAs are a distinct class of single-stranded RNA of ~ 18-25 nucleotides (Zhang et al. 2018a,b; Lin et al. 2020). MIR genes are endogenously transcribed as long precursor transcripts (pri-miRNAs), forming a fold-back hairpin structure with the small RNA embedded in one of its arms (Rogers and Chen 2013; Chorostecki et al. 2017). MiRNAs play a key role in post-transcriptional regulation or repression of translation mechanisms (Tiwari et al. 2020). The mature miRNAs negatively regulate gene expression by binding to the partially complementary sequences in the target messenger RNAs (mRNAs), in their opening reading frame (ORF) or UTR regions of speci c target genes (Zhang et al. 2018a; Liu et al. 2019). Then, cleavage and degradation of mRNA molecules or inhibition of translation are carried out with the cooperation of RISC (Liu et al. 2019). Over hundreds miRNA targets seem to be expressed in the developing embryo underlining the relevant role of miRNAs in embryogenesis (Alves et al. 2020; Jeena et al. 2022). Identifying the miRNAs that regulate somatic embryogenesis extends our knowledge about the regulatory pathways controlling embryogenic transitions (Wójcik et al. 2017; Juárez-González et al. 2019; Siddiqui et al. 2019), with implications for control of cell-speci c gene expression programs according to both spatial and temporal cues (Plotnikova et al. 2019). The proper patterning and morphology of embryos are related to the expression of miRNAs and their
Plant lignocellulosic biomass, mostly composed of polysaccharide-rich secondary cell walls (SCWs)... more Plant lignocellulosic biomass, mostly composed of polysaccharide-rich secondary cell walls (SCWs), provides fermentable sugars that may be used to produce biofuels and biomaterials. However, the complex chemical composition and physical structure of SCWs hinder efficient processing of plant biomass. Understanding the molecular mechanisms underlying SCW deposition is, thus, essential to optimize bioenergy feedstocks. Here, we establish a xylogenic culture as a model system to study SCW deposition in sugarcane; the first of its kind in a C4 grass species. We used auxin and brassinolide to differentiate sugarcane suspension cells into tracheary elements, which showed metaxylem-like reticulate or pitted SCW patterning. The differentiation led to increased lignin levels, mainly caused by S-lignin units, and a rise in p-coumarate, leading to increased p-coumarate:ferulate ratios. RNAseq analysis revealed massive transcriptional reprogramming during differentiation, with upregulation of ge...
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