Plant regeneration capacity in seeds of three species of Miconia (Melastomataceae) may be related to endogenous polyamine profiles.

In plant tissue culture, differences in endogenous levels of species-specific plant growth regulators (PGRs) may explain differences in regenerative capacity. In the case of polyamines (PAs), their dynamics and distribution may vary between species, genotypes, tissues, and developmental pathways, such as sexual reproduction and apomixis. In this study, for the first time, we aimed to assess the impact of varying endogenous PAs levels in seeds from distinct reproductive modes in Miconia spp. (Melastomataceae), on their in vitro regenerative capacity. We quantified the free PAs endogenous content in seeds of Miconia australis (obligate apomictic), Miconia hyemalis (facultative apomictic), and Miconia sellowiana (sexual) and evaluated their in vitro regenerative potential in WPM culture medium supplemented with a combination of 2,4-dichlorophenoxyacetic acid (2,4-D) and 6-benzylaminopurine (BAP). The morphogenic responses were characterized by light microscopy and scanning electron microscopy and discussed regarding the endogenous PAs profiles found. Seeds of M. sellowiana presented approximately eight times more putrescine than M. australis, which was associated with a higher percentage of regenerated calluses (76.67%) than M. australis (5.56%). On the other hand, spermine levels were significantly higher in M. australis. Spermine is indicated as an inhibitor of auxin-carrying gene expression, which may have contributed to its lower regenerative capacity under the tested conditions. These findings provide important insights into in vitro morphogenesis mechanisms in Miconia and highlight the significance of endogenous PA levels in plant regeneration. These discoveries can potentially optimize future regeneration protocols in Miconia, a plant group still underexplored in this area.

Somatic Embryogenesis in Conifers: One Clade to Rule Them All?

Somatic embryogenesis (SE) in conifers is usually characterized as a multi-step process starting with the development of proembryogenic cell masses and followed by histodifferentiation, somatic embryo development, maturation, desiccation, and plant regeneration. Our current understanding of conifers' SE is mainly derived from studies using Pinaceae species as a model. However, the evolutionary relationships between conifers are not clear. Some hypotheses consider conifers as a paraphyletic group and Gnetales as a closely related clade. In this review, we used an integrated approach in order to cover the advances in knowledge on SE in conifers and Gnetales, discussing the state-of-the-art and shedding light on similarities and current bottlenecks. With this approach, we expect to be able to better understand the integration of these clades within current studies on SE. Finally, the points discussed raise an intriguing question: are non-Pinaceae conifers less prone to expressing embryogenic competence and generating somatic embryos as compared to Pinaceae species? The development of fundamental studies focused on this morphogenetic route in the coming years could be the key to finding a higher number of points in common between these species, allowing the success of the SE of one species to positively affect the success of another.

The complete plastid genome of Bactris riparia (Arecaceae) and a comparative analysis in Bactridinae (Cocoseae, Arecaceae).

Here we sequenced and characterized the complete plastome of Bactris riparia, a species closely related to B. gasipaes and widely distributed in Western Amazonia. We performed a comparative genomic analysis with B. riparia and the other four Bactridinae species retrieved from GenBank. The plastome of B. riparia was 156,715 bp with a quadripartite structure. Gene content included 86 protein-coding genes (CDS), 38 tRNAs, and 8 rRNAs. Bactris riparia has 69 more base pairs than B. gasipaes, with identical numbers in IR, and more in LSC and SSC. The comparative analysis indicated that structure, collinearity, and IR/SSC borders of plastomes within subtribe Bactridinae are, in general, conserved. We predicted 69 SSRs in B. riparia plastome. Among them, ~80% consisted of A/T homopolymers. Among the 52 variable CDS, rbcL showed the highest non-synonymous rate, while the rps15 gene had the highest synonymous rate. Three genes (ccsA, cemA, and rpoC1) presented evidence of positive selection and 22 genes showed evidence of purifying selection. The phylogenetic tree based on plastome sequences set Bactris as more closely related to Astrocaryum than to Acrocomia. These new plastome data of B. riparia will contribute to studies about the diversity, evolutionary history, and conservation of palms.

Structural and evolutive features of the Plinia phitrantha and P. cauliflora plastid genomes and evolutionary relationships within tribe Myrteae (Myrtaceae).

Plinia phitrantha and P. cauliflora are Myrtaceae species with recognized horticultural and pharmacological potential. Nevertheless, studies on molecular genetics and the evolution of these species are absent in the literature. In this study, we report the complete plastid genome sequence of these species and an analysis of structural and evolutive features of the plastid genome within the tribe Myrteae. The two plastid genomes present the conserved quadripartite structure and are similar to already reported plastid genomes of Myrteae species concerning the size, number, and order of the genes. A total of 69-70 SSR loci, 353 single nucleotide polymorphisms, and 574 indels were identified in P. phitrantha and P. caulifora. Observed evolutive features of the plastid genomes support the development of programs for the conservation and breeding of Plinia. The phylogenomic analysis based on the complete plastid genome sequence of 15 Myrteae species presented a robust phylogenetic signal and evolutive traits of the tribe. Ten hotspots of nucleotide diversity were identified, evidence of purifying selection was observed in 27 genes, and relative conservation of the plastid genomes was confirmed for Myrteae. Altogether, the outcomes of the present study provide support for planning conservation, breeding, and biotechnological programs for Plinia species.

Reactive Oxygen Species (ROS) Are Not a Key Determinant for Zika Virus-Induced Apoptosis in SH-SY5Y Neuroblastoma Cells.

INTRODUCTION: ZIKV is a highly neurotropic virus that can cause the death of infected neuroprogenitor cells through mitochondrial damage and intrinsic apoptotic signaling. In this context, the role of reactive oxygen species (ROS) in neuronal cell death caused by ZIKV still remains elusive. OBJECTIVE: We aimed at evaluating the role of these cellular components in the death of human undifferentiated neuroblastoma cell line infected with ZIKV. RESULTS: ZIKV infection resulted in the extensive death of SH-SY5Y cells with the upregulation of several genes involved in survival and apoptotic responses as well as the colocalization of mitochondrial staining with ZIKV Envelope (E) protein. Notably, levels of intracellular reactive oxygen species (ROS) were not altered during ZIKV infection in undifferentiated SH-SY5Y cells, and consistent with these results, the treatment of infected cells with the widely studied ROS scavenger N-acetylcysteine (NAC) did not prevent cell death in these cells. CONCLUSION: Altogether, our results suggest that excessive ROS production is not the main trigger of SH-SY5Y cells death in ZIKV infection.

The plastome sequence of Bactris gasipaes and evolutionary analysis in tribe Cocoseae (Arecaceae).

The family Arecaceae is distributed throughout tropical and subtropical regions of the world. Among the five subfamilies, Arecoideae is the most species-rich and still contains some ambiguous inter-generic relationships, such as those within subtribes Attaleinae and Bactridineae. The hypervariable regions of plastid genomes (plastomes) are interesting tools to clarify unresolved phylogenetic relationships. We sequenced and characterized the plastome of Bactris gasipaes (Bactridinae) and compared it with eight species from the three Cocoseae sub-tribes (Attaleinae, Bactridinae, and Elaeidinae) to perform comparative analysis and to identify hypervariable regions. The Bactris gasipaes plastome has 156,646 bp, with 113 unique genes. Among them, four genes have an alternative start codon (cemA, rps19, rpl2, and ndhD). Plastomes are highly conserved within tribe Cocoseae: 97.3% identity, length variation of ~2 kb, and a single ~4.5 kb inversion in Astrocaryum plastomes. The LSC/IR and IR/SSC junctions vary among the subtribes: in Bactridinae and Elaeidinae the rps19 gene is completely contained in the IR region; in the subtribe Attaleinae the rps19 gene is only partially contained in the IRs. The hypervariable regions selected according to sequence variation (SV%) and frequency of parsimony informative sites (PIS%) revealed plastome regions with great potential for molecular analysis. The ten regions with greatest SV% showed higher variation than the plastid molecular markers commonly used for phylogenetic analysis in palms. The phylogenetic trees based on the plastomes and the hypervariable regions (SV%) datasets had well-resolved relationships, with consistent topologies within tribe Cocoseae, and confirm the monophyly of the subtribes Bactridinae and Attaleinae.

Plastid phylogenomics of Pleurothallidinae (Orchidaceae): Conservative plastomes, new variable markers, and comparative analyses of plastid, nuclear, and mitochondrial data.

We present the first comparative plastome study of Pleurothallidinae with analyses of structural and molecular characteristics and identification of the ten most-variable regions to be incorporated in future phylogenetic studies. We sequenced complete plastomes of eight species in the subtribe and compared phylogenetic results of these to parallel analyses of their nuclear ribosomal DNA operon (26S, 18S, and 5.8S plus associated spacers) and partial mitochondrial genome sequences (29-38 genes and partial introns). These plastomes have the typical quadripartite structure for which gene content is similar to those of other orchids, with variation only in the composition of the ndh genes. The independent loss of ndh genes had an impact on which genes border the inverted repeats and thus the size of the small single-copy region, leading to variation in overall plastome length. Analyses of 68 coding sequences indicated the same pattern of codon usage as in other orchids, and 13 protein-coding genes under positive selection were detected. Also, we identified 62 polymorphic microsatellite loci and ten highly variable regions, for which we designed primers. Phylogenomic analyses showed that the top ten mutational hotspots represent well the phylogenetic relationships found with whole plastome sequences. However, strongly supported incongruence was observed among plastid, nuclear ribosomal DNA operon, and mitochondrial DNA trees, indicating possible occurrence of incomplete lineage sorting and/or introgressive hybridization. Despite the incongruence, the mtDNA tree retrieved some clades found in other analyses. These results, together with performance in recent studies, support a future role for mitochondrial markers in Pleurothallidinae phylogenetics.

Plastid genome evolution in Amazonian açaí palm (Euterpe oleracea Mart.) and Atlantic forest açaí palm (Euterpe edulis Mart.).

KEY MESSAGE: The plastomes of E. edulis and E. oleracea revealed several molecular markers useful for genetic studies in natural populations and indicate specific evolutionary features determined by vicariant speciation. Arecaceae is a large and diverse family occurring in tropical and subtropical ecosystems worldwide. E. oleracea is a hyperdominant species of the Amazon forest, while E. edulis is a keystone species of the Atlantic forest. It has reported that E. edulis arose from vicariant speciation after the emergence of the belt barrier of dry environment (Cerrado and Caatinga biomes) between Amazon and Atlantic forests, isolating the E. edulis in the Atlantic forest. We sequenced the complete plastomes of E. edulis and E. oleracea and compared them concerning plastome structure, SSRs, tandem repeats, SNPs, indels, hotspots of nucleotide polymorphism, codon Ka/Ks ratios and RNA editing sites aiming to investigate evolutionary traits possibly affected by distinct environments. Our analyses revealed 303 SNPs, 91 indels, and 82 polymorphic SSRs among both species. Curiously, the narrow correlation among localization of repetitive sequences and indels strongly suggests that replication slippage is involved in plastid DNA mutations in Euterpe. Moreover, most non-synonymous substitutions represent amino acid variants in E. edulis that evolved specifically or in a convergent manner across the palm phylogeny. Amino acid variants observed in several plastid proteins in E. edulis were also identified as positive signatures across palm phylogeny. The higher incidence of specific amino acid changes in plastid genes of E. edulis in comparison with E. oleracea probably configures adaptive genetic variations determined by vicariant speciation. Our data indicate that the environment generates a selective pressure on the plastome making it more adapted to specific conditions.

Characterization of the complete plastid genome of Butia eriospatha (Arecaceae).

Butia eriospatha is an endemic palm species from the Atlantic Rainforest in Brazil, a biodiversity hotspot. This species is currently listed in the IUCN red list as vulnerable and lacks specific plastid markers for population genetics studies. In addition, the evolutionary relationship within the genus Butia is not yet well resolved. Here, we sequenced and characterized the complete plastid genome (plastome) sequence of B. eriospatha. The complete plastome sequence is 154,048 bp in length, with the typical quadripartite structure. This plastome length and genes content is consistent with other six species from tribe Cocoseae. However, the Inverted Repeat (IR) borders show some variation among the analyzed species from this tribe. Species from the Bactridinae (Astrocaryum and Acrocomia) and Elaeidinae (Elaeis) subtribes present the rps19 gene completely duplicated in the IR region. In contrast, all plastomes sequenced from the subtribe Attaleinae (Butia, Cocos, Syagrus) present one complete CDS of rps19 and one partial copy of rps19. The difference in the IR/LSC junctions between Attaleinae and the sister clades Bactridinae + Elaeidinae might be considered an evolutionary signal and the plastome sequence of B. eriopatha may be used in future studies of population genetics and phylogeny.

Comparative Plastid Genomics of Neotropical Bulbophyllum (Orchidaceae; Epidendroideae).

Pantropical Bulbophyllum, with ∼2,200 species, is one of the largest genera in Orchidaceae. Although phylogenetics and taxonomy of the ∼60 American species in the genus are generally well understood, some species complexes need more study to clearly delimit their component species and provide information about their evolutionary history. Previous research has suggested that the plastid genome includes phylogenetic markers capable of providing resolution at low taxonomic levels, and thus it could be an effective tool if these divergent regions can be identified. In this study, we sequenced the complete plastid genome of eight Bulbophyllum species, representing five of six Neotropical taxonomic sections. All plastomes conserve the typical quadripartite structure, and, although the general structure of plastid genomes is conserved, differences in ndh-gene composition and total length were detected. Total length was determined by contraction and expansion of the small single-copy region, a result of an independent loss of the seven ndh genes. Selection analyses indicated that protein-coding genes were generally well conserved, but in four genes, we identified 95 putative sites under positive selection. Furthermore, a total of 54 polymorphic simple sequence repeats were identified, for which we developed amplification primers. In addition, we propose 10 regions with potential to improve phylogenetic analyses of Neotropical Bulbophyllum species.

Identification and characterization of SSR markers of Guadua chacoensis (Rojas) Londoño & P.M. Peterson and transferability to other bamboo species.

The aim of this study was to develop simple sequence repeat (SSR) markers for genetic studies on G. chacoensis, as well as to evaluate their transferability to other bamboo species. Genomic DNA was isolated from G. chacoensis and its partial sequencing was used to find SSR loci. The obtained sequencing data were de novo assembled using the software CLC Genomics Workbench® 8.0v. The SSR loci primers were identified and designed with the software SSRLocator. The selected markers were validated using 56 plants sampled in seven populations from southern Brazil. The markers with potential polymorphism were selected and fluorescently labeled for characterization by capillary electrophoresis. In total, 92 SSR loci were found in G. chacoensis contigs. Suitable primers were designed for 70 SSR loci, and the remaining 22 SSR loci did not have sequences for primer development. Out of 35 selected SSR markers, after PCR optimization, 10 with high polymorphism potential were characterized. These loci can be used in genetic analyses of G. chacoensis and all of them were successfully transferred to other bamboo species. Non-polymorphic loci require further tests with additional plants, from different populations, to identify possibilities of their use.

Molecular relationships of Campomanesia xanthocarpa within Myrtaceae based on the complete plastome sequence and on the plastid ycf2 gene.

Plastomes are very informative structures for comparative phylogenetic and evolutionary analyses. We sequenced and analyzed the complete plastome of Campomanesia xanthocarpa and compared its gene order, structure, and evolutionary characteristics within Myrtaceae. Analyzing 48 species of Myrtaceae, we identified six genes representing 'hotspots' of variability within the plastomes (ycf2, atpA, rpoC2, pcbE, ndhH and rps16), and performed phylogenetic analyses based on: (i) the ycf2 gene, (ii) all the six genes identified as 'hotspots' of variability, and (iii) the genes identified as 'hotspots' of variability, except the ycf2 gene. The structure, gene order, and gene content of the C. xanthocarpa plastome are similar to other Myrtaceae species. Phylogenetic analyses revealed the ycf2 gene as a promissing region for barcoding within this family, having also a robust phylogenetic signal. The synonymous and nonsynonymous substitution rates and the Ka/Ks ratio revealed low values for the ycf2 gene among C. xanthocarpa and the other 47 analyzed species of Myrtaceae, with moderate purifying selection acting on this gene. The average nucleotide identity (ANI) analysis of the whole plastomes produced phylogenetic trees supporting the monophyly of three Myrtaceae tribes. The findings of this study provide support for planning conservation, breeding, and biotechnological programs for this species.

Characterization of sequence variability hotspots in Cranichideae plastomes (Orchidaceae, Orchidoideae).

This study reports complete plastome sequences for six species of Neotropical Cranichideae and focuses on identification of the most variable regions (hotspots) in this group of orchids. These structure of these six plastomes is relatively conserved, exhibiting lengths ranging between 142,599 to 154,562 bp with 36.7% GC on average and exhibiting typical quadripartite arrangement (LSC, SSC and two IRs). Variation detected in the LSC/IR and SSC/IR junctions is explained by the loss of ndhF and ycf1 length variation. For the two genera of epiphytic clade in Spiranthinae, almost whole sets of the ndh-gene family were missing. Eight mutation hotspots were identified based on nucleotide diversity, sequence variability and parsimony-informative sites. Three of them (rps16-trnQ, trnT-trnL, rpl32-trnL) seem to be universal hotspots in the family, and the other five (trnG-trnR, trnR-atpA, trnP-psaJ, rpl32-infA, and rps15-ycf1) are described for the first time as orchid molecular hotspots. These regions have much more variation than all those used previously in phylogenetics of the group and offer useful plastid markers for phylogenetic, barcoding and population genetic studies. The use of whole plastomes or exclusive no-gap matrices also positioned with high support the holomycotrophic Rhizanthella among Orchidoideae plastomes in model-based analyses, showing the utility of plastomes for phylogenetic placement of this unusual genus.

Storage and in vitro germination of orchids (Orchidaceae) seeds from Atlantic Forest - Brazil.

The orchid seed banks of Atlantic Forest may be considered a key strategy for the conservation of species threatened with extinction by indiscriminate collection or habitat destruction. The aim of this study was to evaluate the seed viability, to choose the best culture medium for the asymbiotic germination and evaluate germination, after storage for different periods and temperatures for the Brazilian native orchids: Gomesa praetexta (Rchb.f.) M.W.Chase & N.H.Williams, Gomesa forbesii (Hook.) M.W.Chase & N.H.Williams, Gomesa recurva R.Br. and Grandiphyllum divaricatum (Lindl.) Docha Neto. Knudson C (KC), Murashige & Skoog (MS), half-strength MS (1/2 MS macro- and micro-nutrients) and Woody Plant Medium (WPM) culture media were tested for germination. The WPM culture medium was the best for asymbiotic germination of all species evaluated, with high germination percentages and improved seedling development. Seeds of G. divaricatum, G. praetexta, G. recurva and G. forbesii indicated orthodox behavior, with high viability rates after 12 months of storage, being recommended the storage temperature of -80°C for the first three species and -20°C for G. forbesii. The protocol developed in the present study was efficient for seed bank storage, in vitro germination and seedling production of G. divaricatum and G. praetexta, contributing to conservation strategies of these species.

Applying Human Factors Engineering Methods for Risk Assessment of a Neonatal Incubator.

This research aimed to find main users, frequent utilized tasks, major usability problems, and the context of use of a neonatal incubator (NI) present in a neonatal intensive care unit from a Brazilian hospital and to find out the problems faced by a new user. The chosen methods were the heuristics analysis, contextual investigation, and usability test (UT). Nurses and technicians are the main users of NIs. The predominant contexts of use are the admission of newborns and the replacement of the equipment. Eight selected tasks were performed in the UT, and the most significant problems refer to alarms and configuration of the Air and Skin Modes, because the interface is not intuitive to novice users. Therefore, mitigating errors should be an investment in human factor engineering methods from the beginning of the product development process to the training of the main users.

Genetic, evolutionary and phylogenetic aspects of the plastome of annatto (Bixa orellana L.), the Amazonian commercial species of natural dyes.

MAIN CONCLUSION: The plastome of B. orellana reveals specific evolutionary features, unique RNA editing sites, molecular markers and the position of Bixaceae within Malvales. Annatto (Bixa orellana L.) is a native species of tropical Americas with center of origin in Brazilian Amazonia. Its seeds accumulate the apocarotenoids, bixin and norbixin, which are only found in high content in this species. The seeds of B. orellana are commercially valued by the food industry because its dyes replace synthetic ones from the market due to potential carcinogenic risks. The increasing consumption of B. orellana seeds for dye extraction makes necessary the increase of productivity, which is possible accessing the genetic basis and searching for elite genotypes. The identification and characterization of molecular markers are essential to analyse the genetic diversity of natural populations and to establish suitable strategies for conservation, domestication, germplasm characterization and genetic breeding. Therefore, we sequenced and characterized in detail the plastome of B. orellana. The plastome of B. orellana is a circular DNA molecule of 159,708 bp with a typical quadripartite structure and 112 unique genes. Additionally, a total of 312 SSR loci were identified in the plastome of B. orellana. Moreover, we predicted in 23 genes a total of 57 RNA-editing sites of which 11 are unique for B. orellana. Furthermore, our plastid phylogenomic analyses, using the plastome sequences available in the plastid database belonging to species of order Malvales, indicate a closed relationship between Bixaceae and Malvaceae, which formed a sister group to Thymelaeaceae. Finally, our study provided useful data to be employed in several genetic and biotechnological approaches in B. orellana and related species of the family Bixaceae.

The Crambe abyssinica plastome: Brassicaceae phylogenomic analysis, evolution of RNA editing sites, hotspot and microsatellite characterization of the tribe Brassiceae.

Crambe abyssinica is an important oilseed crop that accumulates high levels of erucic acid, which is being recognized as a potential oil platform for several industrial purposes. It belongs to the family Brassicaceae, assigned within the tribe Brassiceae. Both family and tribe have been the subject of several phylogenetic studies, but the relationship between some lineages and genera remains unclear. Here, we report the complete sequencing and characterization of the C. abyssinica plastome. Plastome structure, gene order, and gene content of C. abyssinica are similar to other species of the family Brassicaceae. The only exception is the rps16 gene, which is absent in many genera within the family Brassicaceae, but seems to be functional in the tribe Brassiceae, including C. abyssinica. However, the analysis of gene divergence shows that the rps16 is the most divergent gene in C. abyssinica and within the tribe Brassiceae. In addition, species of the tribe Brassiceae also show similar SSR loci distribution, with some regions containing a high number of SSRs, which are located mainly at the single copy regions. Six hotspots of nucleotide divergence among Brassiceae species were located in the single copy regions by sliding window analysis. Brassicaceae phylogenomic analysis, based on the complete plastomes of 72 taxa, resulted in a well-supported and well-resolved tree. The genus Crambe is positioned within the Brassiceae clade together with the genera Brassica, Raphanus, Sinapis, Cakile, Orychophragmus and Sinalliaria. Moreover, we report several losses and gains of RNA editing sites that occurred in plastomes of Brassiceae species during evolution.

The complete plastome of macaw palm [Acrocomia aculeata (Jacq.) Lodd. ex Mart.] and extensive molecular analyses of the evolution of plastid genes in Arecaceae.

MAIN CONCLUSION: The plastome of macaw palm was sequenced allowing analyses of evolution and molecular markers. Additionally, we demonstrated that more than half of plastid protein-coding genes in Arecaceae underwent positive selection. Macaw palm is a native species from tropical and subtropical Americas. It shows high production of oil per hectare reaching up to 70% of oil content in fruits and an interesting plasticity to grow in different ecosystems. Its domestication and breeding are still in the beginning, which makes the development of molecular markers essential to assess natural populations and germplasm collections. Therefore, we sequenced and characterized in detail the plastome of macaw palm. A total of 221 SSR loci were identified in the plastome of macaw palm. Additionally, eight polymorphism hotspots were characterized at level of subfamily and tribe. Moreover, several events of gain and loss of RNA editing sites were found within the subfamily Arecoideae. Aiming to uncover evolutionary events in Arecaceae, we also analyzed extensively the evolution of plastid genes. The analyses show that highly divergent genes seem to evolve in a species-specific manner, suggesting that gene degeneration events may be occurring within Arecaceae at the level of genus or species. Unexpectedly, we found that more than half of plastid protein-coding genes are under positive selection, including genes for photosynthesis, gene expression machinery and other essential plastid functions. Furthermore, we performed a phylogenomic analysis using whole plastomes of 40 taxa, representing all subfamilies of Arecaceae, which placed the macaw palm within the tribe Cocoseae. Finally, the data showed here are important for genetic studies in macaw palm and provide new insights into the evolution of plastid genes and environmental adaptation in Arecaceae.

Effects of glutathione supplementation and carbon source duringsomatic embryogenesis of Acca sellowiana (O. Berg) Burret(Myrtaceae) / Efeitos da suplementação de glutationa e fontes de carbono durante a embriogênesesomática de Acca sellowiana (O. Berg) Burret (Myrtaceae)

The present study intended to investigate the effects of different glutathione (GSH) levels (0, 0.1, 0.5 and 1 mM) on the somatic embryogenesis (SE) induction of Acca sellowiana. Besides, we evaluated the effect of different carbon sources (sucrose and maltose) on the somatic embryos conversion. GSH-supplemented treatments resulted in improved SE induction rates (~70%) as compared to the control GSH-free (~35%) after 50 days of culture. The total number of somatic embryos obtained did not differ between treatments, but significant differences were observed for the embryonic stages after 80 days of culture. After 80 days of culture, 0.5 and 1 mM GSH-supplemented treatments showed the largest amount of torpedo-staged somatic embryos. In contrast, treatments supplemented with 0 and 0.1 mM GSH showed equal amounts of somatic embryos at all embryonic stages. These results indicate that GSH accelerates the SE induction process and increases the synchrony of the somatic embryo formation of A. sellowiana. The use of maltose for the somatic embryos conversion, as compared to sucrose, did not influence the conversion rate of normal chlorophyllous somatic embryos, but increased the formation of normal achlorophyllous somatic plantlets. This finding can be attributed to the rapid hydrolysis of sucrose, contributing to an enhanced chlorophyll synthesis.

O presente estudo teve como objetivo investigar o efeito de diferentes níveis de glutationa (GSH) (0, 0,1, 0,5 e 1 mM) na indução da embriogênese somática (ES) de Acca sellowiana. Além disso, avaliamos o efeito de diferentes fontes de carbono (sacarose e maltose) na conversão de embriões somáticos em plântulas. Os tratamentos suplementados com GSH resultaram em melhores taxas de indução de ES (~70%) em comparação com o controle isento de GSH (~35%) após 50 dias de cultivo. Após 80 dias as taxas de indução foram iguais. O número total de embriões somáticos obtidos não diferiu entre os tratamentos, mas diferenças expressivas foram observadas nos estágios embrionários. No dia 80 em cultura, os tratamentos suplementados com 0,5 e 1 mM de GSH mostraram a maior porção de embriões somáticos no estádio torpedo. Diferentemente, tratamentos suplementados com 0 e 0,1 mM de GSH mostraram quantidades iguais de embriões somáticos em todos os estágios embrionários. Estes resultados indicam que o GSH acelera o processo de indução do ES e aumenta a sincronia na formação de embriões somáticos de A. sellowiana. O uso de maltose no meio de cultura de conversão de embriões somáticos, em comparação com a sacarose, não influenciou a taxa de conversão de embriões somáticos clorofílados normais, mas aumentou a formação de plântulas aclorofiladas normais. Esse resultado pode ser atribuído à rápida hidrólise da sacarose, apresentando translocação de plantas mais eficiente e aumento da osmolaridade do meio de cultura, contribuindo para uma síntese melhorada de clorofila.