6 research outputs found
Secondary Metabolism in Amaranthus spp. — A Genomic Approach to Understand Its Diversity and Responsiveness to Stress in Marginally Studied Crops with High Agronomic Potential
Cultivated amaranths are crops with an unrealized agronomical potential despite their high nutritional value and nutraceutic properties of their seeds and/ or leaves. They tolerate growing conditions unsuitable for cereals, and are tolerant to biotic aggressors. Several Amaranthus species are abundant of sources of secondary metabolites, mostly phenylpropanoids, predominantly in seeds and leaves, many of which may confer health benefits associated with their antioxidant properties. They could also act as defensive compounds against predators or pathogens. Recent biochemical and molecular approaches partly defined the mechanisms responsible for grain amaranth´s tolerance against biotic stress. However, the role played by secondary metabolites in (a)biotic stress amelioration in amaranth is practically unknown. Our group has identified several genes coding for enzymes involved in secondary metabolism pathways in A. hypochondriacus, in addition to related regulatory transcription factors. More than 50% of these genes involve the phenylpropanoid pathway. In this chapter, the role played by this pathway in (a)biotic stress amelioration in plants will be briefly reviewed, followed by an examination of its involvement in the conferral of nutraceutic properties to amaranth plants. A description of the progress obtained so far regarding the characterization of phenylpropanoid genes in grain amaranth will close this chapter
Metabolic and enzymatic changes associated with carbon mobilization, utilization and replenishment triggered in grain amaranth (Amaranthus cruentus) in response to partial defoliation by mechanical injury or insect herbivory
Background: Amaranthus cruentus and A. hypochondriacus are crop plants grown for grain production in subtropical countries. Recently, the generation of large-scale transcriptomic data opened the possibility to study representative genes of primary metabolism to gain a better understanding of the biochemical mechanisms underlying tolerance to defoliation in these species. A multi-level approach was followed involving gene expression analysis, enzyme activity and metabolite measurements. Results: Defoliation by insect herbivory (HD) or mechanical damage (MD) led to a rapid and transient reduction of non-structural carbohydrates (NSC) in all tissues examined. This correlated with a short-term induction of foliar sucrolytic activity, differential gene expression of a vacuolar invertase and its inhibitor, and induction of a sucrose transporter gene. Leaf starch in defoliated plants correlated negatively with amylolytic activity and expression of a β-amylase-1 gene and positively with a soluble starch synthase gene. Fatty-acid accumulation in roots coincided with a high expression of a phosphoenolpyruvate/phosphate transporter gene. In all tissues there was a long-term replenishment of most metabolite pools, which allowed damaged plants to maintain unaltered growth and grain yield. Promoter analysis of ADP-glucose pyrophosphorylase and vacuolar invertase genes indicated the presence of cis-regulatory elements that supported their responsiveness to defoliation. HD and MD had differential effects on transcripts, enzyme activities and metabolites. However, the correlation between transcript abundance and enzymatic activities was very limited. A better correlation was found between enzymes, metabolite levels and growth and reproductive parameters.
Conclusions: It is concluded that a rapid reduction of NSC reserves in leaves, stems and roots followed by their long-term recovery underlies tolerance to defoliation in grain amaranth. This requires the coordinate action of genes/enzymes that are differentially affected by the way leaf damage is performed. Defoliation tolerance in grain is a complex process that can’t be fully explained at the transcriptomic level only
The novel and taxonomically restricted Ah24 gene from grain amaranth (Amaranthus hypochondriacus) has a dual role in development and defense
Grain amaranths tolerate stress and produce highly nutritious seeds. We have identified several (a)biotic stress-responsive genes of unknown function in Amaranthus
hypochondriacus, including the so-called Ah24 gene. Ah24 was expressed in young or developing tissues; it was also strongly induced by mechanical damage, insect herbivory
and methyl jasmonate and in meristems and newly emerging leaves of severely defoliated plants. Interestingly, an in silico analysis of its 1304 bp promoter region showed a predominance of regulatory boxes involved in development, but not in defense. The Ah24 cDNA encodes a predicted cytosolic protein of 164 amino acids, the localization of which was confirmed by confocal microscopy. Additional in silico analysis identified
several other Ah24 homologs, present almost exclusively in plants belonging to the Caryophyllales. The possible function of this gene in planta was examined in transgenic Ah24 overexpressing Arabidopsis thaliana and Nicotiana tabacum plants. Transformed Arabidopsis showed enhanced vegetative growth and increased leaf number with no penalty in one fitness component, such as seed yield, in experimental conditions. Transgenic tobacco plants, which grew and reproduced normally, had increased insect
herbivory resistance. Modified vegetative growth in transgenic Arabidopsis coincided with significant changes in the expression of genes controlling phytohormone synthesis or signaling, whereas increased resistance to insect herbivory in transgenic tobacco coincided with higher jasmonic acid and proteinase inhibitor activity levels, plus the accumulation of nicotine and several other putative defense-related metabolites. It is
proposed that the primary role of the Ah24 gene in A. hypochondriacus is to contribute to a rapid recovery post-wounding or defoliation, although its participation in defense against insect herbivory is also plausible
Metabolic and enzymatic changes associated with carbon mobilization, utilization and replenishment triggered in grain amaranth (<it>Amaranthus cruentus</it>) in response to partial defoliation by mechanical injury or insect herbivory
Abstract Background Amaranthus cruentus and A. hypochondriacus are crop plants grown for grain production in subtropical countries. Recently, the generation of large-scale transcriptomic data opened the possibility to study representative genes of primary metabolism to gain a better understanding of the biochemical mechanisms underlying tolerance to defoliation in these species. A multi-level approach was followed involving gene expression analysis, enzyme activity and metabolite measurements. Results Defoliation by insect herbivory (HD) or mechanical damage (MD) led to a rapid and transient reduction of non-structural carbohydrates (NSC) in all tissues examined. This correlated with a short-term induction of foliar sucrolytic activity, differential gene expression of a vacuolar invertase and its inhibitor, and induction of a sucrose transporter gene. Leaf starch in defoliated plants correlated negatively with amylolytic activity and expression of a β-amylase-1 gene and positively with a soluble starch synthase gene. Fatty-acid accumulation in roots coincided with a high expression of a phosphoenolpyruvate/phosphate transporter gene. In all tissues there was a long-term replenishment of most metabolite pools, which allowed damaged plants to maintain unaltered growth and grain yield. Promoter analysis of ADP-glucose pyrophosphorylase and vacuolar invertase genes indicated the presence of cis-regulatory elements that supported their responsiveness to defoliation. HD and MD had differential effects on transcripts, enzyme activities and metabolites. However, the correlation between transcript abundance and enzymatic activities was very limited. A better correlation was found between enzymes, metabolite levels and growth and reproductive parameters. Conclusions It is concluded that a rapid reduction of NSC reserves in leaves, stems and roots followed by their long-term recovery underlies tolerance to defoliation in grain amaranth. This requires the coordinate action of genes/enzymes that are differentially affected by the way leaf damage is performed. Defoliation tolerance in grain is a complex process that can’t be fully explained at the transcriptomic level only.</p
Imaginación mediática en Hispanoamérica : variantología de lo transmedial entre los siglos XVI y XIX / Siegfried Zielinski … [et al] ; Mauricio Vásquez Arias, Diego Fernando Montoya, editores académicos
En el tiempo reciente, Mauricio Vásquez ha desarrollado, en conjunto con un grupo activo de estudiantes de la Maestría en Comunicación Transmedia del Departamento de Comunicación Social de la Universidad EAFIT, un proyecto pedagógico singular el cual consiste en hacer un retrato de la fiesta barroca entre los siglo XVI y XIX. Esta celebración de origen colonial estaba constituida por una serie muy amplia de prácticas escénicas y artefactuales que resultan familiares a la variantología de los medios puestos que, temática y operativamente, hacen referencia a fenómenos mecánicos, ópticos y escénicos descritos por pensadores como el mallorquín Ramón Llull (1232-1315) o el alemán Athanasius Kircher (1602-1680). Algunos de los tópicos expuestos en los nueve capítulos del presente libro son : la curaduría del programa de la fiesta barroca, los jeroglíficos, la arquitectura temporal, los carros alegóricos, el teatro, los gabinetes ópticos, los espectáculos de variedades, las fantasmagorías y las sesiones de espiritismo. Este tipo de investigación es completamente relevante el día de hoy porque Colombia y buena parte de América Latina fueron fundadas como producto de la Contrarreforma, y este fue en buena medida un proceso instrumental, un proceso profundamente mediático que es necesario diseccionar y discutir, para conocer y decolonizar (Mignolo, 2003).Prólogo : variantoscopios / Andrés Burbano -- Imaginación mediática en Hispanoamérica. Variantología de lo transmedial entre los siglo XVI y XIX / Mauricio Vásquez Arias -- Variantología : relaciones de tiempo profundo entre artes, ciencias y tecnologías : una entrevista (ficticia) / Siegfried Zielinski -- Siglo XVI al XVIII : comisariado, organización e invención del programa simbólico de las fiestas barrocas entre los siglos XVI y XVIII en Hispanoamérica / José Luis Acosta Sáenz, María Camila Borrás Santiago, Manuela González Cabrera, Andrés Naranjo Ortiz ; relaciones entre jeroglíficos, concursos, oralidad, arquitectura y arte performativo en la fiesta barroca entre los siglos XVI y XIX / Isabel Cristina Castaño Preciado, Alejandro Gómez Valencia, Juan Felipe Mejía García, Natalia Moreno Londoño, Ángela Tobón Ospina ; claves mediáticas de la arquitectura efímera en la fiesta barroca hispanoamericana / Ángela María Salazar Restrepo, Deicy Johana Pareja Montoya, Juan Gabriel Jaramillo Vásquez, Manuel Alejandro Valencia Zapata ; el carro alegórico como elemento simbólico en la fiesta barroca / Estefanía Jiménez Tamayo, Nicolás Arbeláez Rivera, Alejandra Henao Quiroz, Manuel Recio Gómez ; el teatro en la fiesta barroca : entre la celebración, la conmemoración y el espectáculo / Paula Andrea Álvarez Patiño, Ana María Bolívar Noreña, Yuliola Ximena Flórez Castillón, Kelly Marcela Velásquez Amaya -- Siglo XIX : el gabinete óptico en la España del siglo XIX / Sara Melissa Gallego Quiroz, Elizabeth Montoya Vélez ; manifestaciones del espectáculo de variedades en Iberoamérica durante el siglo XIX / Jennifer Ballestas Avilez, Valeria Zapata Giraldo, Ana Isabel Restrepo Patiño ; la fantasmagoría como espectáculo en la España del siglo XIX / Johny Galvis, Alejandro Agudelo, Johan Sebastián Morales ; uno para "sí", dos para "no" : el montaje de las sesiones espiritistas en la Argentina decimonónica / Daniel Garcíatoro, Juan Fernando Jaramillo Montoya266 p
Transcriptomic analysis of grain amaranth (<it>Amaranthus hypochondriacus</it>) using 454 pyrosequencing: comparison with <it>A. tuberculatus</it>, expression profiling in stems and in response to biotic and abiotic stress
<p>Abstract</p> <p>Background</p> <p><it>Amaranthus hypochondriacus</it>, a grain amaranth, is a C4 plant noted by its ability to tolerate stressful conditions and produce highly nutritious seeds. These possess an optimal amino acid balance and constitute a rich source of health-promoting peptides. Although several recent studies, mostly involving subtractive hybridization strategies, have contributed to increase the relatively low number of grain amaranth expressed sequence tags (ESTs), transcriptomic information of this species remains limited, particularly regarding tissue-specific and biotic stress-related genes. Thus, a large scale transcriptome analysis was performed to generate stem- and (a)biotic stress-responsive gene expression profiles in grain amaranth.</p> <p>Results</p> <p>A total of 2,700,168 raw reads were obtained from six 454 pyrosequencing runs, which were assembled into 21,207 high quality sequences (20,408 isotigs + 799 contigs). The average sequence length was 1,064 bp and 930 bp for isotigs and contigs, respectively. Only 5,113 singletons were recovered after quality control. Contigs/isotigs were further incorporated into 15,667 isogroups. All unique sequences were queried against the nr, TAIR, UniRef100, UniRef50 and Amaranthaceae EST databases for annotation. Functional GO annotation was performed with all contigs/isotigs that produced significant hits with the TAIR database. Only 8,260 sequences were found to be homologous when the transcriptomes of <it>A. tuberculatus </it>and <it>A. hypochondriacus </it>were compared, most of which were associated with basic house-keeping processes. Digital expression analysis identified 1,971 differentially expressed genes in response to at least one of four stress treatments tested. These included several multiple-stress-inducible genes that could represent potential candidates for use in the engineering of stress-resistant plants. The transcriptomic data generated from pigmented stems shared similarity with findings reported in developing stems of Arabidopsis and black cottonwood (<it>Populus trichocarpa</it>).</p> <p>Conclusions</p> <p>This study represents the first large-scale transcriptomic analysis of <it>A. hypochondriacus</it>, considered to be a highly nutritious and stress-tolerant crop. Numerous genes were found to be induced in response to (a)biotic stress, many of which could further the understanding of the mechanisms that contribute to multiple stress-resistance in plants, a trait that has potential biotechnological applications in agriculture.</p