RESUMEN

Foeniculum vulgare Mill. commonly known as fennel, is a globally recognized aromatic medicinal plant and culinary herb with widespread popularity due to its antimicrobial, antioxidant, carminative, and diuretic properties, among others. Although the phenotypic effects of salinity stress have been previously explored in fennel, the molecular mechanisms underlying responses to elevated salinity in this plant remain elusive. MicroRNAs (miRNAs) are tiny, endogenous, and extensively conserved non-coding RNAs (ncRNAs) typically ranging from 20 to 24 nucleotides (nt) in length that play a major role in a myriad of biological functions. In fact, a number of miRNAs have been extensively associated with responses to abiotic stress in plants. Consequently, employing computational methodologies and rigorous filtering criteria, 40 putative miRNAs belonging to 25 different families were characterized from fennel in this study. Subsequently, employing the psRNATarget tool, a total of 67 different candidate target transcripts for the characterized fennel miRNAs were predicted. Additionally, the expression patterns of six selected fennel miRNAs (i.e. fvu-miR156a, fvu-miR162a-3p, fvu-miR166a-3p, fvu-miR167a-5p, fvu-miR171a-3p, and fvu-miR408-3p) were analyzed under salinity stress conditions via qPCR. This article holds notable significance as it identifies not only 40 putative miRNAs in fennel, a non-model plant, but also pioneers the analysis of their expression under salinity stress conditions.

Asunto(s)

Foeniculum , Regulación de la Expresión Génica de las Plantas , MicroARNs , Hojas de la Planta , Estrés Salino , Foeniculum/genética , MicroARNs/genética , MicroARNs/metabolismo , Hojas de la Planta/metabolismo , Hojas de la Planta/genética , Estrés Salino/genética , Perfilación de la Expresión Génica , ARN de Planta/genética , ARN de Planta/metabolismo

RESUMEN

Legumes form a symbiotic association with rhizobia and fix atmospheric nitrogen in specialized root organs known as nodules. It is well known that salt stress inhibits root nodule symbiosis by decreasing rhizobial growth, rhizobial infection, nodule number, and nitrogenase activity in diverse legumes. Despite this knowledge, the genetic and molecular mechanisms governing salt stress's inhibition of nodulation and nitrogen fixation are still elusive. In this Viewpoint, we summarize the most recent knowledge of the genetic mechanisms that shape this symbiosis according to the salt levels in the soil. We emphasize the relevance of modulating the activity of the transcription factor Nodule Inception to properly shape the symbiosis with rhizobia accordingly. We also highlight the knowledge gaps that are critical for gaining a deeper understanding of the molecular mechanisms underlying the adaptation of the root nodule symbiosis to salt-stress conditions. We consider that filling these gaps can help to improve legume nodulation and harness its ecological benefits even under salt-stress conditions.

Asunto(s)

Fabaceae , Rhizobium , Nódulos de las Raíces de las Plantas , Simbiosis/genética , Salinidad , Fabaceae/genética , Fijación del Nitrógeno/genética , Rhizobium/fisiología , Estrés Salino/genética , Nodulación de la Raíz de la Planta/genética

RESUMEN

BACKGROUND: Soil salinity is a problem in more than 100 countries across all continents. It is one of the abiotic stress that threatens agriculture the most, negatively affecting crops and reducing productivity. Transcriptomics is a technology applied to characterize the transcriptome in a cell, tissue, or organism at a given time via RNA-Seq, also known as full-transcriptome shotgun sequencing. This technology allows the identification of most genes expressed at a particular stage, and different isoforms are separated and transcript expression levels measured. Once determined by this technology, the expression profile of a gene must undergo validation by another, such as quantitative real-time PCR (qRT-PCR). This study aimed to select, annotate, and validate stress-inducible genes-and their promoters-differentially expressed in the leaves of oil palm (Elaeis guineensis) plants under saline stress. RESULTS: The transcriptome analysis led to the selection of 14 genes that underwent structural and functional annotation, besides having their expression validated using the qRT-PCR technique. When compared, the RNA-Seq and qRT-PCR profiles of those genes resulted in some inconsistencies. The structural and functional annotation analysis of proteins coded by the selected genes showed that some of them are orthologs of genes reported as conferring resistance to salinity in other species. There were those coding for proteins related to the transport of salt into and out of cells, transcriptional regulatory activity, and opening and closing of stomata. The annotation analysis performed on the promoter sequence revealed 22 distinct types of cis-acting elements, and 14 of them are known to be involved in abiotic stress. CONCLUSION: This study has helped validate the process of an accurate selection of genes responsive to salt stress with a specific and predefined expression profile and their promoter sequence. Its results also can be used in molecular-genetics-assisted breeding programs. In addition, using the identified genes is a window of opportunity for strategies trying to relieve the damages arising from the salt stress in many glycophyte crops with economic importance.

Asunto(s)

Arecaceae , Regulación de la Expresión Génica de las Plantas , Fitomejoramiento , Estrés Salino/genética , Perfilación de la Expresión Génica , Arecaceae/genética , Transcriptoma

RESUMEN

NAC transcription factors play critical roles in xylem secondary development and in regulation of stress response in plants. NAC proteins related to secondary cell wall development were recently identified and characterized in Tectona grandis (teak), one of the hardwood trees of highest economic importance in the world. In this work, we characterized the novel TgNAC01 gene, which is involved in signaling pathways that mediate teak response to stress. Abscisic acid (ABA) increases TgNAC01 expression in teak plants. Therefore, this gene may have a role in signaling events that mediate ABA-dependent osmotic stress responsive in this plant species. Stable expression in tobacco plants showed that the TgNAC01 protein is localized in the cell nucleus. Overexpression of TgNAC01 in two out three independent transgenic tobacco lines resulted in increased growth, leaf senescence and salt tolerance compared to wild type (WT) plants. Moreover, the stress tolerance of transgenic plants was affected by levels of TgNAC01 gene expression. Water potential, gas exchange and chlorophyll fluorescence were used to determine salt stress tolerance. The 35S:TgNAC01-6 line under 300 mM NaCl stress responded with a significant increase in photosynthesis rate, stomatal conductance, transpiration and carboxylation efficiency, but lower water potential compared to WT plants. The data indicate that the TgNAC01 transcription factor acts as a transcriptional activator of the ABA-mediated regulation and induces leaf senescence.

Asunto(s)

Nicotiana , Tolerancia a la Sal , Plantas Modificadas Genéticamente/genética , Tolerancia a la Sal/genética , Nicotiana/genética , Senescencia de la Planta , Proteínas de Plantas/genética , Estrés Salino/genética , Ácido Abscísico/farmacología , Factores de Transcripción/genética , Agua/metabolismo

RESUMEN

Soil salinity is one abiotic stress that threatens agriculture in more than 100 countries. Gliricidia [Gliricidia sepium (Jacq.) Kunth] is a multipurpose tree known for its ability to adapt to a wide range of soils; however, its tolerance limits and responses to salt stress are not yet well understood. In this study, after characterizing the morphophysiological responses of young gliricidia plants to salinity stress, leaf metabolic and transcription profiles were generated and submitted to single and integrated analyses. RNA from leaf samples were subjected to RNA sequencing using an Illumina HiSeq platform and the paired-end strategy. Polar and lipidic fractions from leaf samples were extracted and analyzed on an ultra-high-performance liquid chromatography (UHPLC) coupled with electrospray ionization quadrupole time-of-flight high-resolution mass spectrometry (MS) system. Acquired data were analyzed using the OmicsBox, XCMS Online, MetaboAnalyst, and Omics Fusion platforms. The substrate salinization protocol used allowed the identification of two distinct responses to salt stress: tolerance and adaptation. Single analysis on transcriptome and metabolome data sets led to a group of 5,672 transcripts and 107 metabolites differentially expressed in gliricidia leaves under salt stress. The phenylpropanoid biosynthesis was the most affected pathway, with 15 metabolites and three genes differentially expressed. Results showed that the differentially expressed metabolites and genes from this pathway affect mainly short-term salt stress (STS). The single analysis of the transcriptome identified 12 genes coding for proteins that might play a role in gliricidia response at both STS and long-term salt stress (LTS). Further studies are needed to reveal the mechanisms behind the adaptation response.

Asunto(s)

Fabaceae , Transcriptoma , Fabaceae/genética , Metabolómica , Salinidad , Estrés Salino/genética , Tolerancia a la Sal/genética

RESUMEN

KEY MESSAGE: StCDPK2 is an early player in the salt stress response in potato plants; its overexpression promoted ROS scavenging, chlorophyll stability, and the induction of stress-responsive genes conferring tolerance to salinity. The salinity of soils affects plant development and is responsible for great losses in crop yields. Calcium-dependent protein kinases (CDPKs) are sensor-transducers that decode Ca2+ signatures triggered by abiotic stimuli and translate them into physiological responses. Histochemical analyses of potato plants harboring StCDPK2 promoter fused to the reporter gene ß-glucuronidase (ProStCDPK2:GUS) revealed that GUS activity was high in the leaf blade and veins, it was restricted to root tips and lateral root primordia, and was observed upon stolon swelling. Comparison with ProStCDPK1:GUS and ProStCDPK3:GUS plants revealed their differential activities in the plant tissues. ProStCDPK2:GUS plants exposed to high salt presented enhanced GUS activity in roots which correlated with the numerous stress-responsive sites predicted in its promoter sequence. Moreover, StCDPK2 expression increased in in vitro potato plants after 2 h of high salt exposure and in greenhouse plants exposed to a dynamic stress condition. As inferred from biometric data and chlorophyll content, plants that overexpress StCDPK2 were more tolerant than wild-type plants when exposed to high salt. Overexpressing plants have a more efficient antioxidant system; they showed reduced accumulation of peroxide and higher catalase activity under salt conditions, and enhanced expression of WRKY6 and ERF5 transcription factors under control conditions. Our results indicate that StCDPK2 is an early player in the salt stress response and support a positive correlation between StCDPK2 overexpression and tolerance towards salt stress.

Asunto(s)

Solanum tuberosum , Clorofila/metabolismo , Regulación de la Expresión Génica de las Plantas , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Modificadas Genéticamente/genética , Proteínas Quinasas/genética , Proteínas Quinasas/metabolismo , Estrés Salino/genética , Solanum tuberosum/metabolismo , Estrés Fisiológico/genética

RESUMEN

Soil salinity is one of the most limiting stresses for crop productivity and quality worldwide. In this sense, jasmonates (JAs) have emerged as phytohormones that play essential roles in mediating plant response to abiotic stresses, including salt stress. Here, we reviewed the mechanisms underlying the activation and response of the JA-biosynthesis and JA-signaling pathways under saline conditions in Arabidopsis and several crops. In this sense, molecular components of JA-signaling such as MYC2 transcription factor and JASMONATE ZIM-DOMAIN (JAZ) repressors are key players for the JA-associated response. Moreover, we review the antagonist and synergistic effects between JA and other hormones such as abscisic acid (ABA). From an applied point of view, several reports have shown that exogenous JA applications increase the antioxidant response in plants to alleviate salt stress. Finally, we discuss the latest advances in genomic techniques for the improvement of crop tolerance to salt stress with a focus on jasmonates.

Asunto(s)

Adaptación Fisiológica/genética , Ciclopentanos/metabolismo , Genómica , Oxilipinas/metabolismo , Plantas/genética , Estrés Salino/genética , Tolerancia a la Sal/genética

RESUMEN

Soil salinity is a key problem for crop production worldwide. High salt concentration in soil negatively modulates plant growth and development. In roots, salinity affects the growth and development of both primary and lateral roots. The phytohormone auxin regulates various developmental processes during the plant's life cycle, including several aspects of root architecture. Auxin signaling involves the perception by specialized receptors which module several regulatory pathways. Despite their redundancy, previous studies have shown that their functions can also be context-specific depending on tissue, developmental or environmental cues. Here we show that the over-expression of Auxin Signaling F-Box 3 receptor results in an increased resistance to salinity in terms of root architecture and germination. We also studied possible downstream signaling components to further characterize the role of auxin in response to salt stress. We identify the transcription factor SZF1 as a key component in auxin-dependent salt stress response through the regulation of NAC4. These results give lights of an auxin-dependent mechanism that leads to the modulation of root system architecture in response to salt identifying a hormonal cascade important for stress response.

Asunto(s)

Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Germinación/genética , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Raíces de Plantas/metabolismo , Receptores de Superficie Celular/metabolismo , Estrés Salino/genética , Factores de Transcripción/metabolismo , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Regulación de la Expresión Génica de las Plantas/genética , Germinación/efectos de los fármacos , Péptidos y Proteínas de Señalización Intracelular/genética , Meristema/efectos de los fármacos , Meristema/genética , Meristema/metabolismo , Mutación , Raíces de Plantas/efectos de los fármacos , Raíces de Plantas/genética , Plantas Modificadas Genéticamente , Receptores de Superficie Celular/genética , Salinidad , Estrés Salino/efectos de los fármacos , Transducción de Señal/efectos de los fármacos , Transducción de Señal/genética , Factores de Transcripción/genética , Regulación hacia Arriba

RESUMEN

MAIN CONCLUSION: Accumulation of specific metabolites, mainly γ-aminobutyric acid, polyamines, and proline, was essential to homeostasis regulation and differential salt tolerance in sorghum genotypes. Salinity is severe abiotic stress that limits plant growth and development in arid and semi-arid regions. Survival to abiotic stresses depends on metabolic and sometimes even morphological adjustments. We measured the growth parameters, water relations, the content of ions (Na+, K+, Cl-), compatible solutes [some free amino acids (FAAs) including γ-aminobutyric acid (GABA) and proline and soluble carbohydrates) and polyamines (PAs), the activity of PAs metabolism enzymes, and metabolomic profile in plants after 14 days of salt stress treatment. These analyses were to evaluate the influence of metabolomic responses of sorghum genotypes exhibiting sensitivity (CSF18) or tolerance (CSF20) to salinity on plant growth. The salinity promoted growth reductions and induced increases in Na+ and Cl- content and decreases in K+ content. The water status and osmotic potential (Ψo) were reduced by salt stress, but to minimize damage, especially in the CSF20, the osmolytes and PAs contributed to the osmotic adjustment. The results showed that salinity induced an increase in putrescine (Put) in the sensitive genotype. However, it raised spermidine (Spd), spermine (Spm), and cadaverine (Cad) in the tolerant genotype. In addition, the regulation of polyamine oxidase can be related to Spm and GABA biosynthesis. Differential metabolic changes to salt tolerance include metabolites associated with tricarboxylic acid (TCA) cycle intermediates and the metabolisms of sugars, FAAs, and PAs.

Asunto(s)

Desarrollo de la Planta/genética , Hojas de la Planta/genética , Hojas de la Planta/metabolismo , Tolerancia a la Sal/genética , Tolerancia a la Sal/fisiología , Sorghum/genética , Sorghum/metabolismo , Variación Genética , Genotipo , Desarrollo de la Planta/fisiología , Estrés Salino/genética , Estrés Salino/fisiología

RESUMEN

Soybean is an economically important plant, and its production is affected in soils with high salinity levels. It is important to understand the adaptive mechanisms through which plants overcome this kind of stress and to identify potential genes for improving abiotic stress tolerance. RNA-Seq data of two Glycine max cultivars, a drought-sensitive (C08) and a tolerant (Conquista), subjected to different periods of salt stress were analyzed. The transcript expression profile was obtained using a transcriptogram approach, comparing both cultivars and different times of treatment. After 4 h of salt stress, Conquista cultivar had 1400 differentially expressed genes, 647 induced and 753 repressed. Comparative expression revealed that 719 genes share the same pattern of induction or repression between both cultivars. Among them, 393 genes were up- and 326 down-regulated. Salt stress also modified the expression of 54 isoforms of miRNAs in Conquista, by the maturation of 39 different pre-miRNAs. The predicted targets for 12 of those mature miRNAs also have matches with 15 differentially expressed genes from our analyses. We found genes involved in important pathways related to stress adaptation. Genes from both ABA and BR signaling pathways were modulated, with possible crosstalk between them, and with a likely post-transcriptional regulation by miRNAs. Genes related to ethylene biosynthesis, DNA repair, and plastid translation process were those that could be regulated by miRNA.

Asunto(s)

Glycine max/genética , Estrés Salino/genética , Tolerancia a la Sal/genética , Adaptación Fisiológica/genética , Agricultura/métodos , Sequías , Perfilación de la Expresión Génica/métodos , Regulación de la Expresión Génica de las Plantas/genética , Salinidad , Transducción de Señal/genética , Estrés Fisiológico/genética , Factores de Transcripción/genética , Transcriptoma/genética

RESUMEN

BACKGROUND: Xanthomonas citri subsp. citri (Xcc), the causal agent of citrus canker is maintained as an epiphyte on citrus leaves until entering the plant tissue. During epiphytic survival, bacteria may encounter low water availability that challenges the infection process. Proteomics analyses of Xcc under saline stress, mimicking the conditions found during epiphytic survival, showed increased abundance of a putative NAD(P)H dehydrogenase encoded by XAC2229. METHODS: Expression levels of XAC2229 and a Xcc mutant in XAC2229 were analyzed in salt and oxidative stress and during plant-pathogen interaction. An Escherichia coli expressing XAC2229 was obtained, and the role of this protein in oxidative stress resistance and in reactive oxygen species production was studied. Finally, Xac2229 protein was purified, spectrophotometric and cofactor analyses were done and enzymatic activities determined. RESULTS: XAC2229 was expressed under salt stress and during plant-pathogen interaction. ΔXAC2229 mutant showed less number of cankers and impaired epiphytic survival than the wild type strain. ΔXAC2229 survived less in the presence of H2O2 and produced more reactive oxygen species and thiobarbituric acid-reactive substances than the wild type strain. Similar results were observed for E. coli expressing XAC2229. Xac2229 is a FAD containing flavoprotein, displays diaphorase activity with an optimum at pH 6.0 and has quinone reductase activity using NADPH as an electron donor. CONCLUSIONS: A FAD containing flavoprotein from Xcc is a new NADPH quinone reductase required for bacterial virulence, particularly in Xcc epiphytic survival on citrus leaves. GENERAL SIGNIFICANCE: A novel protein involved in the worldwide disease citrus canker was characterized.

Asunto(s)

NAD(P)H Deshidrogenasa (Quinona)/metabolismo , Xanthomonas/enzimología , Benzoquinonas/metabolismo , Citrus/metabolismo , Citrus/microbiología , Peróxido de Hidrógeno/metabolismo , NAD(P)H Deshidrogenasa (Quinona)/genética , NADP/metabolismo , Estrés Oxidativo , Hojas de la Planta/metabolismo , Estrés Salino/genética , Estrés Salino/fisiología , Virulencia , Xanthomonas/metabolismo , Xanthomonas/patogenicidad , Xanthomonas/fisiología

RESUMEN

Soil salinity is one of the major plant growth and yield-limiting constraints in arid and semi-arid regions of the world. In addition to the oxidative damage, increasing salt stress is associated with elevated cellular ethylene levels due to the synthesis of 1-aminocyclopropane-1-carboxylic acid (ACC) in large amounts. The objective of the current study was to elucidate the inoculation effect of an ACC deaminase (ACCD)-producing phytobeneficial strain Achromobacter sp. FB-14 on rice plants to alleviate the salinity effects by upregulation of the stress-responsive CIPK genes. The strain FB-14 was isolated by using nutrient agar medium at 855 mM NaCl concentration and it was taxonomically identified as Achromobacter sp. with more than 99% 16S rRNA gene sequence similarity with many Achromobacter species. The strain FB-14 demonstrated substantial in vitro potential for ACCD activity, synthesis of indole compounds, and phosphate solubilization up to 100 mM NaCl concentration in the culture medium. The gene corresponding to ACCD activity (acdS) was amplified and sequenced in order to confirm the inherent enzyme activity of the strain at a molecular level. The rifampicin-resistant derivative of strain FB-14 was recovered from the rice rhizosphere on antibiotic medium up to 21 days of sowing. Moreover, the strain FB-14 was inoculated on rice plants under salinity and it not only enhanced the growth of rice plants in terms of root and shoot length, and fresh and dry weight, but also upregulated the expression of stress-responsive CIPK genes (OsCIPK03, OsCIPK12, and OsCIPK15) according to the results of qRT-PCR analysis. To the best of our knowledge, this is the first report deciphering the role of plant-beneficial Achromobacter strain relieving the rice plants from salt stress by promoting the growth and enhancing the expression of stress-responsive CIPK genes.

Asunto(s)

Achromobacter/enzimología , Liasas de Carbono-Carbono/metabolismo , Oryza/crecimiento & desarrollo , Oryza/microbiología , Proteínas Serina-Treonina Quinasas/genética , Estrés Salino/genética , Achromobacter/genética , Regulación de la Expresión Génica de las Plantas , Oryza/genética , ARN Ribosómico 16S/genética , Suelo/química , Microbiología del Suelo , Regulación hacia Arriba

RESUMEN

Salinity and water deficiency are abiotic factors which have a strong impact on agricultural activities, especially in arid and semi-arid regions. The aim of this research was to analyse the tolerance of two genotypes of forage sorghum, EA 116 and BRS Ponta Negra, to different levels of water and salt stress during germination. The conditions of water and salt stress were simulated by moistening the substrate with a solution of mannitol and of sodium chloride (NaCl) respectively, with the water potential adjusted to 0 (distilled water), -0.1, -0.2, -0.3, -0.4, -0.5 and -0.6 MPa. The variables under analysis were germination percentage, first count, germination speed index, shoot and root length, seedling dry weight, electrolyte leakage and leaf Na+/K+ ratio. The experiment was conducted in a completely randomised design, and distributed in a 2 (genotypes) × 2 (stress condition) × 7 (osmotic potential) factorial scheme, with four replications. The EA 116 and BRS Ponta Negra genotypes show greater tolerance to water stress. The EA 116 cultivar maintained germination under water stress from 0 to -0.6MPa and saline stress from 0 to -0.4 MPa.

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A salinidade e a deficiência hídrica são fatores abióticos com forte impacto sobre as atividades agrícolas, especialmente, em regiões áridas e semiáridas. Objetivou-se com a pesquisa analisar a tolerância de dois genótipos de sorgo forrageiro, EA 116 e BRS Ponta Negra, a diferentes níveis de estresse hídrico e salino durante a germinação. As condições de estresse hídrico e salino foram simuladas a partir do umedecimento do substrato com solução de manitol e Cloreto de Sódio (NaCl), respectivamente, com potencial hídrico ajustadas em: 0 (água destilada); -0,1; -0,2; -0,3; -0,4; -0,5 e -0,6 MPa. As variáveis analisadas foram Porcentagem de germinação, primeira contagem, índice de velocidade de germinação, comprimento da parte aérea e radicular, massa seca da plântula, extravasamento de eletrólitos e a relação Na+/K+ das folhas. Conduzido em delineamento inteiramente casualizado, distribuídos em esquema de fatorial 2 (genótipos) × 2 (condição de estresse) × 7 (potencial osmótico), com quatro repetições. Os genótipos EA 116 e BRS Ponta Negra apresentam maior tolerância ao estresse hídrico. A cultivar EA116 manteve a germinação em condições de estresse hídrico de 0 a -0,6 MPa e salina de 0 a -0,4 MPa.

Asunto(s)

Deshidratación , Estrés Fisiológico , Estrés Salino/genética , Homeostasis , Sorghum/crecimiento & desarrollo

RESUMEN

Salinity and water deficiency are abiotic factors which have a strong impact on agricultural activities, especially in arid and semi-arid regions. The aim of this research was to analyse the tolerance of two genotypes of forage sorghum, EA 116 and BRS Ponta Negra, to different levels of water and salt stress during germination. The conditions of water and salt stress were simulated by moistening the substrate with a solution of mannitol and of sodium chloride (NaCl) respectively, with the water potential adjusted to 0 (distilled water), -0.1, -0.2, -0.3, -0.4, -0.5 and -0.6 MPa. The variables under analysis were germination percentage, first count, germination speed index, shoot and root length, seedling dry weight, electrolyte leakage and leaf Na+/K+ ratio. The experiment was conducted in a completely randomised design, and distributed in a 2 (genotypes) × 2 (stress condition) × 7 (osmotic potential) factorial scheme, with four replications. The EA 116 and BRS Ponta Negra genotypes show greater tolerance to water stress. The EA 116 cultivar maintained germination under water stress from 0 to -0.6MPa and saline stress from 0 to -0.4 MPa.(AU)

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A salinidade e a deficiência hídrica são fatores abióticos com forte impacto sobre as atividades agrícolas, especialmente, em regiões áridas e semiáridas. Objetivou-se com a pesquisa analisar a tolerância de dois genótipos de sorgo forrageiro, EA 116 e BRS Ponta Negra, a diferentes níveis de estresse hídrico e salino durante a germinação. As condições de estresse hídrico e salino foram simuladas a partir do umedecimento do substrato com solução de manitol e Cloreto de Sódio (NaCl), respectivamente, com potencial hídrico ajustadas em: 0 (água destilada); -0,1; -0,2; -0,3; -0,4; -0,5 e -0,6 MPa. As variáveis analisadas foram Porcentagem de germinação, primeira contagem, índice de velocidade de germinação, comprimento da parte aérea e radicular, massa seca da plântula, extravasamento de eletrólitos e a relação Na+/K+ das folhas. Conduzido em delineamento inteiramente casualizado, distribuídos em esquema de fatorial 2 (genótipos) × 2 (condição de estresse) × 7 (potencial osmótico), com quatro repetições. Os genótipos EA 116 e BRS Ponta Negra apresentam maior tolerância ao estresse hídrico. A cultivar EA116 manteve a germinação em condições de estresse hídrico de 0 a -0,6 MPa e salina de 0 a -0,4 MPa.(AU)

Asunto(s)

Sorghum/crecimiento & desarrollo , Estrés Salino/genética , Homeostasis , Estrés Fisiológico , Deshidratación

RESUMEN

Methylation/demethylation of cytosines is an epigenetic strategy for transcriptional regulation, allowing organisms to rapidly respond and adapt to different stimuli. In this context, and using Arabidopsis thaliana as a plant model, we explored whether an environmental stress is sufficient to trigger a change in the methylation status of Glabra-2, a master gene associated with root epidermal cell differentiation. As this gene acts mainly in the epidermis in the root, we examined the stress-driven methylation levels specifically in that tissue. We focused on the stress caused by different salt concentrations in the growth medium. When testing the effect of 20 and 75 mM NaCl, we found that there is a significant decrease in the CG methylation level of the analyzed genomic region within the epidermis. Whereas this reduction was 23% in mildly stressed plants, it turned out to be more robust (33%) in severely stressed ones. Notably, this latter epigenetic change was accompanied by an increase in the number of trichoblasts, the epidermal cell type responsible for root hair development. Analysis of an eventual inheritance of epigenetic marks showed that the non-stressed progeny (F1) of stressed plants did not inherit-in a Lamarckian fashion-the methylation changes that had been acquired by the parental individuals.

Asunto(s)

Proteínas de Arabidopsis/genética , Arabidopsis/genética , Diferenciación Celular/genética , Metilación de ADN/genética , Proteínas de Homeodominio/genética , Epidermis de la Planta/genética , Raíces de Plantas/genética , Estrés Salino/genética , Diferenciación Celular/efectos de los fármacos , Metilación de ADN/efectos de los fármacos , Epigénesis Genética , Epigenómica/métodos , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Epidermis de la Planta/citología , Raíces de Plantas/citología , Cloruro de Sodio/farmacología , Estrés Fisiológico/efectos de los fármacos , Estrés Fisiológico/genética

RESUMEN

SCO (synthesis of cytochrome c oxidase) proteins are involved in the insertion of copper during the assembly of cytochrome c oxidase (COX), the final enzyme of the mitochondrial respiratory chain. Two SCO proteins, namely, homolog of copper chaperone 1 and 2 (HCC1 and HCC2) are present in seed plants, but HCC2 lacks the residues involved in copper binding, leading to uncertainties about its function. In this study, we performed a transcriptomic and phenotypic analysis of Arabidopsis thaliana plants with reduced expression of HCC1 or HCC2. We observed that a deficiency in HCC1 causes a decrease in the expression of several stress-responsive genes, both under basal growth conditions and after applying a short-term high salinity treatment. In addition, HCC1 deficient plants show a faster decrease in chlorophyll content, photosystem II quantum efficiency and COX levels after salinity stress, as well as a faster increase in alternative oxidase capacity. Notably, HCC2 deficiency causes opposite changes in most of these parameters. Bimolecular fluorescence complementation analysis indicated that both proteins are able to interact. We postulate that HCC1 is a limiting factor for COX assembly during high salinity conditions and that HCC2 probably acts as a negative modulator of HCC1 activity through protein-protein interactions. In addition, a direct or indirect role of HCC1 and HCC2 in the gene expression response to stress is proposed.

Asunto(s)

Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Proteínas Transportadoras de Cobre/genética , Proteínas Transportadoras de Cobre/metabolismo , Complejo IV de Transporte de Electrones/metabolismo , Membranas Mitocondriales/metabolismo , Proteínas Mitocondriales/genética , Proteínas Mitocondriales/metabolismo , Estrés Salino/genética , Estrés Salino/fisiología