Accumulation of specific flavonoids in soybean (Glycine max (L.) Merr.) as a function of the early tripartite symbiosis with arbuscular mycorrhizal fungi and Bradyrhizobium japonicum (Kirchner) Jordan     

Pedro M. Antunes  Amarilis de Varennes  Michael J. Goss 《Soil biology & biochemistry》2006,38(6):1234-1242

This study is the first report assessing the effect of soil inoculation on the signalling interaction of Bradyrhizobium japonicum, arbuscular mycorrhizal fungi (AMF) and soybean plants throughout the early stages of colonisation that lead to the tripartite symbiosis. In a study using soil disturbance to produce contrasting indigenous AMF treatments, the flavonoids daidzein, genistein and coumestrol were identified as possible signals for regulating the establishment of the tripartite symbiosis. However, it was unclear whether soil disturbance induced changes in flavonoid root accumulation other than through changing the potential for AMF colonization. In this study, soil treatments comprising all possible combinations of AMF and B. japonicum were established to test whether (1) modifications in root flavonoid accumulation depend on the potential for AMF colonization, and (2) synthesis and accumulation of flavonoids in the roots change over time as a function of the early plant-microbial interactions that lead to the tripartite symbiosis. The study was comprised of two phases. First, maize was grown over 3-week periods to promote the development of the AM fungus Glomus clarum. Second, the interaction between soybean, G. clarum and B. japonicum was evaluated at 6, 10, 14 and 40 days after plant emergence. Root colonization by G. clarum had a positive effect on nodulation 14 days after emergence, producing, 30% more nodules which were 40% heavier than those on roots solely inoculated with B. japonicum. The tripartite symbiosis resulted in 23% more N₂ being fixed than did the simpler symbiosis between soybean and B. japonicum. The presence of both symbionts changed accumulation of flavonoids in roots. Daidzein and coumestrol increased with plant growth. However, development of the tripartite symbiosis caused a decrease in coumestrol; accumulation of daidzein, the most abundant flavonoid, was reduced in the presence of AMF.  相似文献   

Genetic variability evaluation in a Moroccan collection of barley, Hordeum vulgare L., by means of storage proteins and RAPDs     

EL-Habib Dakir  María-Luisa Ruiz  Pedro García  Marcelino Pérez de la Vega 《Genetic Resources and Crop Evolution》2002,49(6):619-631

The genetic variation existing in a set of barley (Hordeum vulgare L.) landrace samples recently collected in Morocco was estimated. Two kinds of genetic markers, seed storage proteins (hordeins) and random amplified polymorphic DNA (RAPD), were used. Only six out of 31 landraces were subjected to RAPD analysis. Both kinds of markers, RAPD and storage proteins, yielded similar results, showing that the level of variation observed in Moroccan barley was high: all landraces showed variability; 808 different storage protein patterns (multilocus associations) were observed among 1897 individuals (2.32 seeds per association, on average) with an average of 43 multilocus associations per accession. In general, genetic variation within accessions was higher than between accessions. The 100 polymorphic RAPD bands generated by 21 effective primers were able to generate enough patterns to differentiate between uniform cultivars and even between individuals in variable accessions. One of the aims of this work was to compare the effectiveness of RAPD versus storage protein techniques in assessing the variability of genetic resource collections. On average hordeins were more polymorphic than RAPDs: they showed more alternatives per band on gels and a higher percentage of polymorphic bands, although RAPDs supply a higher number of bands. Although RAPD is an easy and standard technique, storage protein analysis is technically easier, cheaper and needs less sophisticated equipment. Thus, when resources are a limiting factor and considering the cost of consumables and work time, seed storage proteins must be the technique of choice for a first estimation of genetic variation in plant genetic resource collections.  相似文献   

Effect of tillage and N fertilization on microbial physiological profile of soils cultivated with wheat     

Gabriela Diosma  Mnica Aulicino  Hugo Chidichimo  Pedro A. Balatti 《Soil & Tillage Research》2006,91(1-2):236-243

Microbial diversity might be a good indicator of ecosystem disturbance and functioning. We determined the effect of soil disturbances, such as N fertilization and tillage management, on soil microbial communities in a Typic Argiudoll of the El Salado river basin (Argentina). Microbial activity and substrate utilization provided a metabolic fingerprint of the soil microbial community. Univariate and multivariate analyses were used to differentiate responses to N fertilization and tillage at each of three growth stages of wheat (Triticum aestivum L.). Tillage had an adverse effect on microbial diversity, in which reduced and conventional tillage treated soils had different populations. However, N fertilization also altered microbial diversity depending on the crop developmental stage considered. Metabolism of carboxylic acids and carbohydrates were the main indicators of functional microbial activity and diversity. Although the substrate consumption profile of 32 C substrates did not provide insights into the fundamental ecological interactions that may induce changes in microbial population, it allowed us to demonstrate the alterations of microbial diversity as a result of tillage. We conclude that tillage and N fertilization altered microbial diversity.  相似文献   

Variation and phylogeny of the triploid cultivated potatoSolanum chaucha Juz. et Buk. based on RAPD and isozyme markers     

Pedro L. Cisneros  Carlos F. Quiros 《Genetic Resources and Crop Evolution》1995,42(4):373-386

Ninety four accessions of the cultivated triploid potatoS. chaucha were analyzed and classified in genotypic groups using 9 isozyme loci and RAPD markers disclosed by 20 arbitrary 10-mer primers. Eight isozyme loci out of nine were polymorphic. A total of 22 allozymes were analyzed but none of them were specific for any genotypic group. About half (52%) of the 102 RAPD markers scored, were polymorphic, all of them showing polymorphism among groups and rarely within groups. Eighteen RAPD markers were specific for certain genotypes. The isozyme markers showed a certain amount of intra group variation which made classification less reliable than with RAPD markers. A total of 10 triploid genetic groups were discriminated using both techniques together. A single primer was found to be sufficient to distinguish all 10 groups. All varieties of a single group are considered to have been derived from the same cross and then clonally propagated, even though there is a high amount of morphological variation within a single genotypic group due probably to somatic mutations. RAPD markers have been shown to be more reliable in the classification of triploid potato varieties than other genetic markers like isozymes, proteins and morphological traits.  相似文献   

Ciliates in a waste stabilization pond system in Mexico     

Fermin Rivera  M. Rosario Sanchez  Alfonso Lugo  Pedro Ramirez  Ricardo Ortiz  Arturo Calderon 《Water, air, and soil pollution》1987,34(3):245-262

A protozoological survey was performed on a waste-stabilization pond to isolate, identify, and determine the incidence of ciliates present in these waters. The correlation between the species found and the physicochemical parameters was investigated. One hundred and eighty samples were analyzed from February 1983 to February 1984. Free-living ciliates isolated include:Carchesium polypinum Linnaeus,Vorticella microstoma Ehrenberg,Vorticella convallaria Linnaeus,Didinium balbiani Fabré-Domergue,Amphileptus claparedei Stein,Spathidium spathula Müller,Litonotus fasciola Ehrenberg,Paramecium caudatum Müller,Paramecium aurelia Ehrenberg,Tetrahymena vorax Kidder,Tetrahymena pyriformis Ehrenberg,Cyclidium glaucoma Müller,Aspidisca costata Ehrenberg, andStylonychia putrina Stokes. The performance of the pond was predominantly anaerobic. The temperature, total alkalinity, and nitrate concentration were the most variable parameters in the system studied.  相似文献   

Self‐pollination does not affect fruit set or fruit characteristics in almond (Prunus dulcis)     

Pedro J. Martínez‐García  Encarnación Ortega  Federico Dicenta 《Plant Breeding》2011,130(3):367-371

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Ecology. Soil fertility and hunger in Africa     

Sanchez PA 《Science (New York, N.Y.)》2002,295(5562):2019-2020

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Microbiology. TB--a new target, a new drug     

Cole ST  Alzari PM 《Science (New York, N.Y.)》2005,307(5707):214-215

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Deep Impact observations by OSIRIS onboard the Rosetta spacecraft   总被引：1，自引：0，他引：1  

Keller HU  Jorda L  Küppers M  Gutierrez PJ  Hviid SF  Knollenberg J  Lara LM  Sierks H  Barbieri C  Lamy P  Rickman H  Rodrigo R 《Science (New York, N.Y.)》2005,310(5746):281-283

The OSIRIS cameras (optical, spectroscopic, and infrared remote imaging system) onboard the European Space Agency's Rosetta spacecraft observed comet 9P/Tempel 1 for 17 days continuously around the time of NASA's Deep Impact mission. The cyanide-to-water production ratio was slightly enhanced in the impact cloud, compared with that of normal comet activity. Dust particles were flowing outward in the coma at >160 meters per second, accelerated by the gas. The slope of the brightness increase showed a dip about 200 seconds after the impact. Dust Afrho values before and long after the impact confirm the slight decrease of cometary activity. The dust-to-water mass ratio was much larger than 1.  相似文献   

Thermohaline fine structure in an oceanographic front from seismic reflection profiling   总被引：13，自引：0，他引：13  

Holbrook WS  Páramo P  Pearse S  Schmitt RW 《Science (New York, N.Y.)》2003,301(5634):821-824

We present acoustic images of oceanic thermohaline structure created from marine seismic reflection profiles across the major oceanographic front between the Labrador Current and the North Atlantic Current. The images show that distinct water masses can be mapped, and their internal structure imaged, using low-frequency acoustic reflections from sound speed contrasts at interfaces across which temperature changes. The warm/cold front is characterized by east-dipping reflections generated by thermohaline intrusions in the uppermost 1000 meters of the ocean. Our results imply that marine seismic reflection techniques can provide excellent spatial resolution of important oceanic phenomena, including thermohaline intrusions, internal waves, and eddies.  相似文献