RESUMEN
This study characterizes seedling exudates of peas, tomatoes, and cucumbers at the level of chemical composition and functionality. A plant experiment confirmed that Rhizobium leguminosarum bv. viciae 3841 enhanced growth of pea shoots, while Azospirillum brasilense Sp7 supported growth of pea, tomato, and cucumber roots. Chemical analysis of exudates after 1 day of seedling incubation in water yielded differences between the exudates of the three plants. Most remarkably, cucumber seedling exudate did not contain detectable sugars. All exudates contained amino acids, nucleobases/nucleosides, and organic acids, among other compounds. Cucumber seedling exudate contained reduced glutathione. Migration on semi solid agar plates containing individual exudate compounds as putative chemoattractants revealed that R. leguminosarum bv. viciae was more selective than A. brasilense, which migrated towards any of the compounds tested. Migration on semi solid agar plates containing 1:1 dilutions of seedling exudate was observed for each of the combinations of bacteria and exudates tested. Likewise, R. leguminosarum bv. viciae and A. brasilense grew on each of the three seedling exudates, though at varying growth rates. We conclude that the seedling exudates of peas, tomatoes, and cucumbers contain everything that is needed for their symbiotic bacteria to migrate and grow on.
Asunto(s)
Azospirillum brasilense , Cucumis sativus , Pisum sativum , Rhizobium leguminosarum , Plantones , Solanum lycopersicum , Solanum lycopersicum/microbiología , Solanum lycopersicum/crecimiento & desarrollo , Cucumis sativus/microbiología , Cucumis sativus/crecimiento & desarrollo , Plantones/crecimiento & desarrollo , Plantones/microbiología , Rhizobium leguminosarum/crecimiento & desarrollo , Rhizobium leguminosarum/metabolismo , Azospirillum brasilense/crecimiento & desarrollo , Azospirillum brasilense/metabolismo , Pisum sativum/microbiología , Pisum sativum/crecimiento & desarrollo , Raíces de Plantas/microbiología , Raíces de Plantas/crecimiento & desarrollo , Quimiotaxis , Exudados de Plantas/química , Exudados de Plantas/metabolismoRESUMEN
Plants host a diverse microbiome and differentially react to the fungal species living as endophytes or around their roots through emission of volatiles. Here, using divided Petri plates for Arabidopsis-T. atroviride co-cultivation, we show that fungal volatiles increase endogenous sugar levels in shoots, roots and root exudates, which improve Arabidopsis root growth and branching and strengthen the symbiosis. Tissue-specific expression of three sucrose phosphate synthase-encoding genes (AtSPS1F, AtSPS2F and AtSPS3F), and AtSUC2 and SWEET transporters revealed that the gene expression signatures differ from those of the fungal pathogens Fusarium oxysporum and Alternaria alternata and that AtSUC2 is largely repressed either by increasing carbon availability or by perception of the fungal volatile 6-pentyl-2H-pyran-2-one. Our data point to Trichoderma volatiles as chemical signatures for sugar biosynthesis and exudation and unveil specific modulation of a critical, long-distance sucrose transporter in the plant.
Asunto(s)
Arabidopsis/crecimiento & desarrollo , Hypocreales/química , Sacarosa/metabolismo , Compuestos Orgánicos Volátiles/farmacología , Arabidopsis/efectos de los fármacos , Arabidopsis/genética , Arabidopsis/metabolismo , Transporte Biológico , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Glucosa/metabolismo , Glucosiltransferasas/genética , Proteínas de Transporte de Membrana/genética , Proteínas de Transporte de Membrana/metabolismo , Exudados de Plantas/metabolismo , Hojas de la Planta/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Raíces de Plantas/crecimiento & desarrollo , Plantas Modificadas Genéticamente , Pironas/farmacología , Plantones/crecimiento & desarrollo , Plantones/metabolismo , Sacarosa/farmacologíaRESUMEN
The possibility of inducing polyploidy in grasses by treatment with colchicine and its effect on the production and root exudate content of 2,4-dihydroxy-7-methoxy-2 H-1,4-benzoxazin-3-one (DIMBOA) and 2,4-dihydroxy-2 H-benzoxazin-3-one (DIBOA) was studied in wheat, corn, and rye. Caryopses treated with colchicine at concentrations in the range of 0.1-10 mg/mL for 8 and 48 h and with inoculation of the growth medium are markedly affected in terms of both the distribution and concentration levels of allelochemicals in plants. A greater accumulation was observed in the root with respect to the stem, and this increased with an increasing concentration of colchicine and with treatment time. Analysis of the compounds released by root exudates showed that treatment with colchicine at a concentration higher than 1 mg/mL caused a significant increase in the concentrations of allelochemicals measured in the growth medium. It is proposed that treatment with colchicine of seedling caryopses mixoploids plant populations and that the overall effect is an increase in the levels of allelochemicals released. The ecological implications of this behavior are discussed along with the impact of plant-plant interactions (allelopathy).
Asunto(s)
Benzoxazinas/metabolismo , Colchicina/farmacología , Feromonas/metabolismo , Exudados de Plantas/metabolismo , Poliploidía , Secale/efectos de los fármacos , Triticum/efectos de los fármacos , Zea mays/efectos de los fármacos , Raíces de Plantas/efectos de los fármacos , Raíces de Plantas/genética , Raíces de Plantas/crecimiento & desarrollo , Raíces de Plantas/metabolismo , Secale/genética , Secale/metabolismo , Plantones/efectos de los fármacos , Plantones/genética , Plantones/crecimiento & desarrollo , Plantones/metabolismo , Triticum/genética , Triticum/metabolismo , Zea mays/genética , Zea mays/metabolismoRESUMEN
Environmental mixed pollution by both organic and inorganic compounds are detected worldwide. Phytoremediation techniques have been proposed as ecofriendly methods for cleaning up polluted sites. Several studies have demonstrated enhanced dissipation of contaminants at the root-soil interface through an increase in microbial activity caused by the release of plant root exudates (REs). The aim of this study was to evaluate the effectiveness for Cr(VI) and lindane removal by Streptomyces M7 cultured in a co-contaminated system in presence of maize REs. Our results showed when REs were added to the contaminated minimal medium (MM) as the only carbon source, microbial removal of Cr(VI) and lindane increased significantly in comparison to contaminant removal obtained in MM with glucose 1 g L-1 . The maximum removal of 91% of lindane and 49.5% of Cr(VI) were obtained in the co-contaminated system. Moreover, Streptomyces M7 showed plant growth promoting traits which could improve plant performance in contaminated soils. The results presented in this study provide evidence that maize REs improved growth of Streptomyces M7 when REs were used as a carbon source in comparison to glucose. Consequently, lindane and Cr(VI) removal was considerably enhanced making evident the phytoremediation potential of the actinobacteria-plant partnership.
Asunto(s)
Carcinógenos Ambientales/metabolismo , Cromo/metabolismo , Hexaclorociclohexano/metabolismo , Insecticidas/metabolismo , Exudados de Plantas/metabolismo , Streptomyces/metabolismo , Zea mays/metabolismo , Carbono/metabolismo , Medios de Cultivo/química , Exudados de Plantas/aislamiento & purificación , Raíces de Plantas/metabolismo , Streptomyces/crecimiento & desarrolloRESUMEN
Biosynthetic investigation of quinonemethide triterpenoid 22ß-hydroxy-maytenin (2) from in vitro root cultures of Peritassa laevigata (Celastraceae) was conducted using (13)C-precursor. The mevalonate pathway in P. laevigata is responsible for the synthesis of the quinonemethide triterpenoid scaffold. Moreover, anatomical analysis of P. laevigata roots cultured in vitro and in situ showed the presence of 22ß-hydroxy-maytenin (2) and maytenin (1) in the tissues from transverse or longitudinal sections with an intense orange color. MALDI-MS imaging confirmed the distribution of (2) and (1) in the more distal portions of the root cap, the outer cell layers, and near the vascular cylinder of P. laevigata in vitro roots suggesting a role in plant defense against infection by microorganisms as well as in the root exudation processes.
Asunto(s)
Antioxidantes/metabolismo , Magnoliaceae , Exudados de Plantas/metabolismo , Raíces de Plantas/metabolismo , Espermidina/análogos & derivados , Antioxidantes/química , Células Cultivadas , Técnicas In Vitro , Indolquinonas/química , Redes y Vías Metabólicas , Ácido Mevalónico/metabolismo , Exudados de Plantas/química , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción , Espermidina/química , Espermidina/metabolismo , Triterpenos/químicaRESUMEN
Several studies have described the effects of seed exudates against microorganisms, but only few of them have investigated the proteins that have defensive activity particularly against nematode parasites. This study focused on the proteins released in the exudates of soybean seeds and evaluated their nematicidal properties against Meloidogyne incognita. A proteomic approach indicated the existence of 63 exuded proteins, including ß-1,3-glucanase, chitinase, lectin, trypsin inhibitor, and lipoxygenase, all of which are related to plant defense. The presence of some of these proteins was confirmed by their in vitro activity. The soybean exudates were able to reduce the hatching of nematode eggs and to cause 100% mortality of second-stage juveniles (J2). The pretreatment of J2 with these exudates resulted in a 90% reduction of the gall number in tobacco plants. These findings suggest that the exuded proteins are directly involved in plant defense against soil pathogens, including nematodes, during seed germination.
Asunto(s)
Antinematodos/química , Glycine max/química , Exudados de Plantas/química , Proteínas de Plantas/química , Proteoma/química , Semillas/química , Tylenchoidea/efectos de los fármacos , Animales , Antinematodos/metabolismo , Antinematodos/farmacología , Espectrometría de Masas , Exudados de Plantas/metabolismo , Exudados de Plantas/farmacología , Proteínas de Plantas/metabolismo , Proteínas de Plantas/farmacología , Proteoma/metabolismo , Proteoma/farmacología , Semillas/metabolismo , Glycine max/metabolismo , Tylenchoidea/crecimiento & desarrolloRESUMEN
Arabidopsis thaliana defective in induced resistance 1 (At-DIR1) has been characterized as a protein responsible for the generation or transmission of the still unknown signal involved in systemic acquired resistance. This acidic apoplastic protein is a member of the family of lipid transfer proteins and was detected in vascular fluids. To our knowledge, no DIR1-like protein has been described in other plant species. Hence, we have performed data mining to identify a putative ortholog of DIR1 in tomato. This strategy allowed the detection of a few gene products displaying sequence similarity to At-DIR1 whose structural features were further analysed in silico. The best match (unigene SGN-327306) encoded a protein with an acidic pI, a peculiar characteristic of DIR1 among lipid transfer proteins, and was hence selected as a putative tomato ortholog of At-DIR1. This sequence, named Le-DIR1, served for the design of a specific antigenic peptide and the generation of polyclonal antibodies. The antiserum anti-Le-DIR1 recognized a peptide of the expected size (7kDa) in phloem sap of tomato plants, hence confirming the existence of the predicted protein in vascular fluids. This result supports the notion of the existence of common systemic acquired resistance (SAR) signaling molecules in different species.
Asunto(s)
Proteínas de Arabidopsis/metabolismo , Proteínas Portadoras/metabolismo , Floema/metabolismo , Exudados de Plantas/metabolismo , Proteínas de Plantas/metabolismo , Homología de Secuencia de Aminoácido , Solanum lycopersicum/metabolismo , Secuencia de Aminoácidos , Arabidopsis , Proteínas de Arabidopsis/química , Proteínas Portadoras/química , Proteínas de Unión a Ácidos Grasos , Datos de Secuencia Molecular , Proteínas de Plantas/química , Alineación de SecuenciaRESUMEN
The induction of several secondary metabolites in plants is one of the most commonly observed effects after the external addition of methyl jasmonate (MeJA). After the elicitation of Catharanthus roseus hairy roots with different concentrations of MeJA, changes in the accumulation of alkaloids such as ajmalicine, serpentine, ajmaline and catharanthine were observed. In addition to the increased accumulation of alkaloids in the tissues, the root exudation of phytochemicals increased compared to that of the non-treated control hairy roots. Moreover, MeJA induced differential secretion of several C. roseus hairy root metabolites.
Asunto(s)
Acetatos/farmacología , Catharanthus/metabolismo , Ciclopentanos/farmacología , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Oxilipinas/farmacología , Raíces de Plantas/metabolismo , Alcaloides de Triptamina Secologanina/análisis , Análisis de Varianza , Catharanthus/genética , Cromatografía Líquida de Alta Presión , Exudados de Plantas/análisis , Exudados de Plantas/metabolismo , Raíces de Plantas/química , Alcaloides de Triptamina Secologanina/metabolismoRESUMEN
In this work the influence of four different ligands present in the xylem sap of Quercus ilex (histidine, citric, oxalic and aspartic acids) on Ni(II) adsorption by xylem was investigated. Grinded xylem was trapped in acrylic columns and solutions of Ni(II), in the absence and presence of the four ligands prepared in KNO(3) 0.1molL(-1) at pH 5.5, were percolated through the column. Aliquots of solutions were recovered in the column end for Ni determination by graphite furnace atomic absorption spectrometry (GFAAS). The experimental data to describe Ni sorption by xylem in both the presence and absence of ligands was better explained by the Freundlich isotherm model. The decreasing affinity order of ligands for Ni was: oxalic acid>citric acid>histidine>aspartic acid. On the other hand, the Ni(II) adsorption by xylem increased following the inverse sequence of ligands. Potentiometric titrations of acidic groups were carried out to elucidate the sorption site groups available in Q. ilex xylem. The potentiometric titration has shown three sorption sites: pK(a) 2.6 (57.7% of the sorption sites), related to monobasic aliphatic carboxylic acids or nitrogen aromatic bases, pK(a) 8.1 (9.6%) and pK(a) 9.9 (32.7%), related to phenolic groups.
Asunto(s)
Níquel/metabolismo , Exudados de Plantas/metabolismo , Quercus/metabolismo , Árboles/metabolismo , Xilema/metabolismo , Ácidos , Adsorción , Biodegradación Ambiental , Ligandos , Modelos Biológicos , Potenciometría , TemperaturaRESUMEN
The rhizobacterium Azospirillum brasilense Sp245 swims, swarms (Swa(+) phenotype) or, very rarely, migrates with the formation of granular macrocolonies (Gri(+) phenotype). Our aims were (i) to identify Sp245 mutants that swarm faster than the parent strain or differ from it in the mode of spreading and (ii) to compare the mutants' responses to wheat seedling exudates. In isotropic liquid media, the swimming speeds of all motile A. brasilense strains were not influenced by the exudates. However, the exudates significantly stimulated the swarming of Sp245. In several Sp245 mutants, the superswarming phenotype was insensitive to local colonial density and to the presence of wheat seedling exudates. An A. brasilense polar-flagellum-defective Gri(+) mutant BK759.G gave rise to stable Swa(++) derivatives with restored flagellum production. This transition was concurrent with plasmid rearrangements and was stimulated in the presence of wheat seedling exudates. The swarming rate of the Swa(++) derivatives of BK759.G was affected by the local density of their colonies but not by the presence of the exudates.