Roles of non-coding RNA in sugarcane-microbe interaction

Studies have highlighted the importance of non-coding RNA regulation in plant-microbe interaction. However, the roles of sugarcane microRNAs (miRNAs) in the regulation of disease responses have not been investigated. Firstly, we screened the sRNA transcriptome of sugarcane infected with Acidovorax avenae. Conserved and novel miRNAs were identified. Additionally, small interfering RNAs (siRNAs) were aligned to differentially expressed sequences from the sugarcane transcriptome. Interestingly, many siRNAs aligned to a transcript encoding a coppertransporter gene whose expression was induced in the presence of A. avenae, while the siRNAs were repressed in the presence of A. avenae. Moreover, a long intergenic non-coding RNA was identified as a potential target or decoy of miR408. To extend the bioinformatics analysis, we carried out independent inoculations and the expression patterns of six miRNAs were validated by quantitative reverse transcription-PCR (qRT-PCR). Among these miRNAs, miR408—a copper- microRNA—was downregulated. The cleavage of a putative miR408 target, a laccase, was confirmed by a modified 50RACE (rapid amplification of cDNA ends) assay. MiR408 was also downregulated in samples infected with other pathogens, but it was upregulated in the presence of a beneficial diazotrophic bacteria. Our results suggest that regulation by miR408 is important in sugarcane sensing whether microorganisms are either pathogenic or beneficial, triggering specific miRNA-mediated regulatory mechanisms accordingly

Ontogenia de los estróbilos, desarrollo de los esporangios y aportes al proceso de esporogénesis de <i>Equisetum giganteum</i> (Equisetaceae) de los Andes de Colombia

Studies on the ontogeny of the strobilus, sporangium and reproductive biology of this group of ferns are scarce. Here we describe the ontogeny of the strobilus and sporangia, and the process of sporogenesis using specimens of E. giganteum from Colombia collected along the Rio Frio, Distrito de Sevilla, Piedecuesta, Santander, at 2 200m altitude. The strobili in different stages of development were fixed, dehydrated, embedded in paraffin, sectioned using a rotatory microtome and stained with the safranin O and fast green technique. Observations were made using differential interference contrast microscopy (DIC) or Nomarski microscopy, an optical microscopy illumination technique that enhances the contrast in unstained, transparent. Strobili arise and begin to develop in the apical meristems of the main axis and lateral branches, with no significant differences in the ontogeny of strobili of one or other axis. Successive processes of cell division and differentiation lead to the growth of the strobilus and the formation of sporangiophores. These are formed by the scutellum, the manubrium or pedicel-like, basal part of the sporangiophore, and initial cells of sporangium, which differentiate to form the sporangium wall, the sporocytes and the tapetum. There is not formation of a characteristic arquesporium, as sporocytes quickly undergo meiosis originating tetrads of spores. The tapetum retains its histological integrity, but subsequently the cell walls break down and form a plasmodium that invades the sporangial cavity, partially surrounding the tetrads, and then the spores. Towards the end of the sporogenesis the tapetum disintegrates leaving spores with elaters free within the sporangial cavity. Two layers finally form the sporangium wall: the sporangium wall itself, with thickened, lignified cell walls and an underlying pyknotic layer. The mature spores are chlorofilous, morphologically similar and have exospore, a thin perispore and two elaters. This study of the ontogeny of the spore-producing structures and spores is the first contribution of this type for a tropical species of the genus. Fluorescence microscopy indicates that elaters and the wall of the sporangium are autofluorescent, while other structures induced fluorescence emitted by the fluorescent dye safranin O. The results were also discussed in relation to what is known so far for other species of Equisetum, suggesting that ontogenetic processes and structure of characters sporoderm are relatively constant in Equisetum, which implies important diagnostic value in the taxonomy of the group.Laboratorio de Estudios de Anatomía Vegetal Evolutiva y Sistemátic

Ontogenia del esporangio y esporogénesis del licopodio Huperzia brevifolia (Lycopodiaceae) de las altas montañas de Colombia

Se describe la ontogenia y la esporogénesis en H. brevifolia, en material recolectado en el Parque Nacional Natural El Cocuy (Boyacá-Colombia) a 4200m de altitud. Los esporangios se desarrollan de forma basípeta sobre el eje caulinar: los iniciales y juveniles se localizan en el ápice y los adultos a maduros, en la base. El desarrollo se inicia a partir de un grupo de células epidérmicas localizadas en las axilas que forman los microfilos con el eje caulinar. Estas células se dividen activamente por mitosis formando una masa celular externa y otra interna. La primera da origen a la pared del esporangio, de varios estratos celulares; de éstos, el estrato externo desarrolla engrosamientos en las paredes anticlinales y en la periclinal interna. El estrato celular interno se diferencia para formar el tapete secretor. Los demás estratos celulares de la pared se degradan durante la maduración del esporangio. La masa celular interna da origen al tejido esporógeno que forma los esporocitos, que experimentan la meiosis I hasta la etapa de díada. La meiosis II concluye con la formación de tétradas, constituidas por esporas en disposición tetraédrica. Las esporas son foveoladas con abertura trilete y son liberadas del esporangio a través de la dehiscencia.Sporangia ontogeny and sporogenesis of the lycopodium Huperzia brevifolia (Lycopodiaceae) from the high mountains of Colombia. Huperzia brevifolia is one of the dominant species of the genus Huperzia living in paramos and superparamos from the Colombian Andes. A detailed study of the sporangium’s ontogeny and sporogenesis was carried out using specimens collected at 4200m above sea level, in Parque Natural Nacional El Cocuy, Colombia. Small pieces of caulinar axis bearing sporangia were fixed, dehydrated, paraffin embedded, sectioned in a rotatory microtome, and stained using the common Safranin O-Fast Green technique; handmade cross sections were also made, stained with aqueous Toluidine Blue (TBO). The sporangia develops basipetally, a condition that allows observation of all the developmental stages taking place throughout the caulinar axis of adult plants. Each sporangium originates from a group of epidermal cells, axilar to the microphylls. These cells undergo active mitosis, and produce new external and internal cellular groups. The sporangium wall and the tapetum originate from the external group of cells, while the internal cellular group leads to the sporogenous tissue. Meiosis occur in the sporocytes and produce simultaneous types tetrads, each one giving rise four trilete spores, with foveolate ornamentation. During the sporangium ripening, the outermost layer of the wall develops anticlinally, and inner periclinal thickenings and the innermost one perform as a secretory tapetum, which persists until the spores are completely mature. All other cellular layers colapse. Rev. Biol. Trop. 57 (4): 1141-1152. Epub 2009 December 01

Ontogenia de los estróbilos, desarrollo de los esporangios y aportes al proceso de esporogénesis de <i>Equisetum giganteum</i> (Equisetaceae) de los Andes de Colombia

Studies on the ontogeny of the strobilus, sporangium and reproductive biology of this group of ferns are scarce. Here we describe the ontogeny of the strobilus and sporangia, and the process of sporogenesis using specimens of E. giganteum from Colombia collected along the Rio Frio, Distrito de Sevilla, Piedecuesta, Santander, at 2 200m altitude. The strobili in different stages of development were fixed, dehydrated, embedded in paraffin, sectioned using a rotatory microtome and stained with the safranin O and fast green technique. Observations were made using differential interference contrast microscopy (DIC) or Nomarski microscopy, an optical microscopy illumination technique that enhances the contrast in unstained, transparent. Strobili arise and begin to develop in the apical meristems of the main axis and lateral branches, with no significant differences in the ontogeny of strobili of one or other axis. Successive processes of cell division and differentiation lead to the growth of the strobilus and the formation of sporangiophores. These are formed by the scutellum, the manubrium or pedicel-like, basal part of the sporangiophore, and initial cells of sporangium, which differentiate to form the sporangium wall, the sporocytes and the tapetum. There is not formation of a characteristic arquesporium, as sporocytes quickly undergo meiosis originating tetrads of spores. The tapetum retains its histological integrity, but subsequently the cell walls break down and form a plasmodium that invades the sporangial cavity, partially surrounding the tetrads, and then the spores. Towards the end of the sporogenesis the tapetum disintegrates leaving spores with elaters free within the sporangial cavity. Two layers finally form the sporangium wall: the sporangium wall itself, with thickened, lignified cell walls and an underlying pyknotic layer. The mature spores are chlorofilous, morphologically similar and have exospore, a thin perispore and two elaters. This study of the ontogeny of the spore-producing structures and spores is the first contribution of this type for a tropical species of the genus. Fluorescence microscopy indicates that elaters and the wall of the sporangium are autofluorescent, while other structures induced fluorescence emitted by the fluorescent dye safranin O. The results were also discussed in relation to what is known so far for other species of Equisetum, suggesting that ontogenetic processes and structure of characters sporoderm are relatively constant in Equisetum, which implies important diagnostic value in the taxonomy of the group.Facultad de Ciencias Naturales y Muse

Ontogenia de los estróbilos, desarrollo de los esporangios y aportes al proceso de esporogénesis de <i>Equisetum giganteum</i> (Equisetaceae) de los Andes de Colombia

Studies on the ontogeny of the strobilus, sporangium and reproductive biology of this group of ferns are scarce. Here we describe the ontogeny of the strobilus and sporangia, and the process of sporogenesis using specimens of E. giganteum from Colombia collected along the Rio Frio, Distrito de Sevilla, Piedecuesta, Santander, at 2 200m altitude. The strobili in different stages of development were fixed, dehydrated, embedded in paraffin, sectioned using a rotatory microtome and stained with the safranin O and fast green technique. Observations were made using differential interference contrast microscopy (DIC) or Nomarski microscopy, an optical microscopy illumination technique that enhances the contrast in unstained, transparent. Strobili arise and begin to develop in the apical meristems of the main axis and lateral branches, with no significant differences in the ontogeny of strobili of one or other axis. Successive processes of cell division and differentiation lead to the growth of the strobilus and the formation of sporangiophores. These are formed by the scutellum, the manubrium or pedicel-like, basal part of the sporangiophore, and initial cells of sporangium, which differentiate to form the sporangium wall, the sporocytes and the tapetum. There is not formation of a characteristic arquesporium, as sporocytes quickly undergo meiosis originating tetrads of spores. The tapetum retains its histological integrity, but subsequently the cell walls break down and form a plasmodium that invades the sporangial cavity, partially surrounding the tetrads, and then the spores. Towards the end of the sporogenesis the tapetum disintegrates leaving spores with elaters free within the sporangial cavity. Two layers finally form the sporangium wall: the sporangium wall itself, with thickened, lignified cell walls and an underlying pyknotic layer. The mature spores are chlorofilous, morphologically similar and have exospore, a thin perispore and two elaters. This study of the ontogeny of the spore-producing structures and spores is the first contribution of this type for a tropical species of the genus. Fluorescence microscopy indicates that elaters and the wall of the sporangium are autofluorescent, while other structures induced fluorescence emitted by the fluorescent dye safranin O. The results were also discussed in relation to what is known so far for other species of Equisetum, suggesting that ontogenetic processes and structure of characters sporoderm are relatively constant in Equisetum, which implies important diagnostic value in the taxonomy of the group.Facultad de Ciencias Naturales y Muse

Ontogenia del esporangio y esporogénesis del licopodio Huperzia brevifolia (Lycopodiaceae) de las altas montañas de Colombia

Se describe la ontogenia y la esporogénesis en H. brevifolia, en material recolectado en el Parque Nacional Natural El Cocuy (Boyacá-Colombia) a 4200m de altitud. Los esporangios se desarrollan de forma basípeta sobre el eje caulinar: los iniciales y juveniles se localizan en el ápice y los adultos a maduros, en la base. El desarrollo se inicia a partir de un grupo de células epidérmicas localizadas en las axilas que forman los microfilos con el eje caulinar. Estas células se dividen activamente por mitosis formando una masa celular externa y otra interna. La primera da origen a la pared del esporangio, de varios estratos celulares; de éstos, el estrato externo desarrolla engrosamientos en las paredes anticlinales y en la periclinal interna. El estrato celular interno se diferencia para formar el tapete secretor. Los demás estratos celulares de la pared se degradan durante la maduración del esporangio. La masa celular interna da origen al tejido esporógeno que forma los esporocitos, que experimentan la meiosis I hasta la etapa de díada. La meiosis II concluye con la formación de tétradas, constituidas por esporas en disposición tetraédrica. Las esporas son foveoladas con abertura trilete y son liberadas del esporangio a través de la dehiscencia

Dual RNA-seq of maize and H. seropedicae ZAE94 association, in different doses of nitrate, reveals novel insights into Plant-PGPB-environment relationship

The interactions between plants, beneficial bacteria and their environment are profoundly shaped by various environmental factors, including light, temperature, water availability, and soil quality. Despite efforts to elucidate the molecular mechanisms involved in the association between plants and beneficial bacteria, like Plant Growth-Promoting Bacteria (PGPB), with many studies focusing on the transcriptional reprogramming in the plant, there is no report on the modulation of genetic controls from both plant and associated bacteria standpoints, in response to environment. The main goal of this study was to investigate the relationship between plant-bacteria-environment signaling, using as a model maize plants inoculated with H. seropedicae ZAE94 and cultivated with different doses of N (0.3 and 3 mM). For this purpose, we performed rRNA-depleted RNA-seq to determine the global gene expression of both maize roots and associated H. seropedicae ZAE94. Our results revealed a differential modulation of maize nitrogen metabolism, phytohormone and cell wall responses when associated with H. seropedicae ZAE94 at different N concentrations. In parallel, a modulation of the bacterial metabolism could be observed, by regulating genes involved in transport, secretion system, cell mobility, oxidoreductases, and chemotaxis, when bacteria were associated with maize roots and cultivated at different doses of N. The molecular and phenotypic data of maize plantlets suggested that different doses of N fertilization differentially regulated the beneficial effects of bacterial inoculation, as higher doses (3 mM) favored shoot elongation and lower doses (0.3 mM) favored increase in plant biomass. Our results provide a valuable integrated overview of differentially expressed genes in both maize and associated H. seropedicae ZAE94 in response to different N availability, revealing new insights into pathways involved in grass-PGPB associations