Dietrich Werner

Plant surface microbiology

Plant surface microbiology , Plant surface microbiology , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

Multilocus sequence analysis for assessment of the biogeography and evolutionary genetics of four Bradyrhizobium species that nodulate soybeans on the asiatic continent.

ABSTRACT A highly supported maximum-likelihood species phylogeny for the genus Bradyrhizobium was inferred from a supermatrix obtained from the concatenation of partial atpD, recA, glnII, and rpoB sequences corresponding to 33 reference strains and 76 bradyrhizobia isolated from the nodules of Glycine max (soybean) trap plants inoculated with soil samples from Myanmar, India, Nepal, and Vietnam. The power of the multigene approach using multiple strains per species was evaluated in terms of overall tree resolution and phylogenetic congruence, representing a practical and portable option for bacterial molecular systematics. Potential pitfalls of the approach are highlighted. Seventy-five of the isolates could be classified as B. japonicum type Ia (USDA110/USDA122-like), B. liaoningense, B. yuanmingense, or B. elkanii, whereas one represented a novel Bradyrhizobium lineage. Most Nepalese B. japonicum Ia isolates belong to a highly epidemic clone closely related to strain USDA110. Significant phylogenetic evidence against the monophyly of the of B. japonicum I and Ia lineages was found. Analysis of their DNA polymorphisms revealed high population distances, significant genetic differentiation, and contrasting population genetic structures, suggesting that the strains in the Ia lineage are misclassified as B. japonicum. The DNA polymorphism patterns of all species conformed to the expectations of the neutral mutation and population equilibrium models and, excluding the B. japonicum Ia lineage, were consistent with intermediate recombination levels. All species displayed epidemic clones and had broad geographic and environmental distribution ranges, as revealed by mapping climate types and geographic origins of the isolates on the species tree.

Nitrogen Fixation in Agriculture, Forestry, Ecology, and the Environment

Preface to the Series. Preface. List of Contributors. 1: Production and Biological Nitrogen Fixation of Tropical Legumes D. Werner 1. Introduction 2. Phaseolus sp. and Vigna sp. (Beans) 3. Arachis hypogaea (Groundnut, Peanut) 4. Cicer arietinum (Chickpea) 5. Cajanus cajan (Pigeon pea) 6. Mucuna pruriens (Velvet bean) and Other Legumes Acknowledgements References 2: Nitrogen Fixation by Soybean in North America S. G. Pueppke 1. Soybean: Pathways to North America and Establishment as a Crop 2. Soybean Production in North America 3. Major Soybean Cropping Systems 4. Biological Nitrogen Fixation by Soybean in North America 5. Perspectives Acknowledgements References 3: The Importance of Nitrogen Fixation to Soybean Cropping in South America M. Hungria, J. C. Franchini, R. J. Campo and P. H. Graham 1. Introduction 2. Taxonomy, Origins, and Importance of Soybean 3. Biological Nitrogen Fixation 4. Economic Importance of Biological Nitrogen Fixation (BNF) in South America 5. Crop Management in South America 6. Final Considerations Acknowledgement References 4: Production, Regional Distribution of Cultivars, and Agricultural Aspects of Soybean in India S. K. Mahna 1. Introduction and Historical Background 2. All-India Area Coverage, Productivity, and Production of Soybean between 1970- 2003 3. All-India State-wise Area Coverage, Productivity, and Production of Soybean 4. Regional Distribution of Soybean Cultivars 5. Regional Agricultural Aspects of Soybean Cultivation Acknowledgements References 5: Soybean Cultivation and BNF in China J. E. Ruiz Sainz, J. C. Zhou, D.-N. Rodriguez-Navarro, J. M. Vinardell and J. E. Thomas-Oates 1. Summary 2. Soybean Cultivation in China: Historical Aspects and Current Situation 3. Nitrogen-Fixing Bacteria that Nodulate Soybean 4. The Soybean Germplasm Collection in China 5. Soybean in Crop Rotation and in Continuous Culture 6. Conclusions Acknowledgement References 6: Soil Stress Factors Influencing Symbiotic Nitrogen Fixation M. J. Sadowsky 1. Introduction 2. Importance of Symbiotic Nitrogen Fixation 3. Symbiotic Interaction of Legumes with Rhizobia 4. Nodulation and Nitrogen-Fixation Genetics in the Rhizobia and Bradyrhizobia 5. Rhizobia in the Soil Environment 6. Stress Factors in the Soil Environment that Influence N2 Fixation 7. Concluding Remarks References 7: Nodulated Legume Trees J. I. Sprent 1. Introduction 2. Leguminosae 3. Rhizobia that Nodulate Legume Trees 4. Types of Nodules formed on Trees 5. Mycorrhizas and Other Nutrient-Acquisition Systems 6. Measurement of Nitrogen Fixation by Trees 7. Role of Legume Trees in Natural and Managed Systems References 8. Nitrogen Fixing Trees with Actinorhiza in Forestry and Agroforestry R. O. Russo 1. Introduction 2. General Characteristics of the Actinorhizal Symbiosis 3. Host Botanical Families 4. Nitrogen Fixation in Actinorhizal Trees 5. Mycorrhizal Associations with Actinorhizal Trees 6. Actinorhizal Trees in Agroforestry 7. The Genus Casaurina 8. The Experience of the Central America Fuelwood Project 9. The Case of Alnus acuminata in Tropical Highlands 10. Other Uses of Actinorhizal Trees 11. Concluding Considerations References 9: Molecular Ecology of N2-fixing Microbes Associated with Gramineous Plants: Hidden Activities of Unknown Bacteria T. Hurek and B. Reinhold-Hurek

The distribution of 14C-TNT in different biochemical compartments of the monocotyledonous Triticum aestivum

Abstract 14 C-TNT was used to quantify the uptake rate and metabolic turnover of 2,4,6-trinitrotoluene (TNT) in Triticum aestivum . Plants were analysed by the special cell fractionation method described by Sens et al. (Environmental Science and Pollution Research, in press). 14 C partitioned to wheat with 43% in the cytoplasm and 57% in the cell wall. Three unpolar and more than ten polar TNT-metabolites were detected by thin layer chromatography in the cytoplasm of wheat. Two of these unpolar metabolites are identified as 2-amino-4,6-dinitrotoluene (2-ADNT) and 4-amino-2,6-dinitrotoluene (4-ADNT). In the cell wall 27% of 14 C taken up or adsorbed by wheat was detected in the lignin fraction. Gel permeation chromatography indicates a covalent linkage of TNT-metabolites with lignin. The molecular weight of lignin metabolites was between 1000–80 000 g/mol in relation to polystyrene standards.

Development of Nodules of Glycine max Infected with an Ineffective Strain of Rhizobium japonicum

Bacteroids in ineffective (nitrogenase negative) nodules of Glycine max, infected with Rhizobium japonicum 61-A-24, as compared to those in effective nodules are characterized by reduced specific activities of alanine dehydrogenase to 15%, of 3-hydroxybutyrate dehydrogenase to 50%, and an increase of glutamine synthetase to 400%. In the plant cytoplasm of ineffective nodules, glutamine synthetase activity is reduced to 10–30%, glutamate dehydrogenase to 50–70%, and the aspartate aminotransferase and alanine aminotransferase are enhanced to 120–200%, depending on the age of the nodules. The total pool of soluble amino acids is reduced to 52 μmol per g nodule fresh weight, as compared to 186 μmol in effective nodules, with a replacement of asparagine (42 mol% of the amino acids) by an unknown amino compound. This compound is absent in nitrogenase, repressed and derepressed, free-living Rhizobium japonicum cells and in the uninfected root tissue. In nitrogenase derepressed, as compared to the repressed free-living cells of Rhizobium japonicum 61-A-101, arginine shows the most obvious change with a reduction to less than one tenth. The ultrastructure of the ineffective nodule is different from the effective organ even in the early stages. The membrane envelopes of the infection vacuoles are decomposing in heavily infected cells within 18 to 20 d after infection. In lightly infected cells very large vacuoles develop with only a few bacteroids inside. No close associations of cristae-rich mitochondria with amyloplasts are observed as in effective nodules. The uninfected cells keep their large starch granules even 40 d after infection. Some poly-β-hydroxybutyrate accumulation in the bacteroids is observed but only in the early stages, and it is almost absent in old nodules (40 d). At this age the infected cells are obviously compressed by uninfected cells, whereas in effective nodules with nitrogenase activity and leghaemoglobin formation, the infected cells have a much higher osmotic pressure than the neighbouring uninfected cells.

Soybean Root Response to Symbiotic Infection Glyceollin I Accumulation in an Ineffective Type of Soybean Nodules with an Early Loss of the Peribacteroid Membrane

A glyceollin I accumulation of about 6000 pmol · mg dry weight-, a tenfold increase above control root tissue, was found in one type of nodule from Glycine max which had been infected with a fix- strain (61-A-24) of Rhizobium japonicum. In nodules infected with one other ineffective (fix-) strain of Rhizobium japonicum (RH 31-Marburg) or with two fix+ strains of Rhizobium japonicum (61-A-101 and USD A 110) no increase in glyceollin I concentrations above control values was found at either 20 d or 34 d after infection. Nodules infected with Rhizobium japonicum 61-A-24 are distinguished by an early loss of the peribacteroid membrane in the infected host cell, whilst the bacteroids themselves remain stable.

Effects of Rhizobium tropici, R. etli, and R. leguminosarum bv. phaseoli on nod Gene-Inducing Flavonoids in Root Exudates of Phaseolus vulgaris

Flavonoids play an important role as signal molecules in the early stages of the legume-Rhizobium symbiosis. The flavonoid content in root exudates of individual seedlings of Phaseolus vulgaris cv. Rab39 was determined by a sensitive method that combines absorption onto cellulose acetate filter strips with separation, identification, and quantification of individual compounds by high-performance liquid chromatography/diode-array detector and gas chromatography-mass spectroscopy analyses. We identified six flavonoids, daidzein, coumestrol, naringenin, genistein, liquiritigenin, and isoliquiritigenin, the latter two of which had not previously been found in bean root exudate. Biological activities were demonstrated by induction of β-galactosidase activity in a Rhizobium leguminosarum bv. phaseoli strain containing a nodC::lacZ fusion controlled by the nodD1 gene. Root exudate of common bean that had been inoculated with symbiotic R. etli, R. leguminosarum bv. phaseoli, or R. tropici contained more of the is...

Legume root metabolites and VA-mycorrhiza development

Summary The communication by phenylpropane-metabolites between symbiotic microorganisms and their legume host plants was further studied by the elucidation of root segment-specific exudation of aromatic compounds. The excreted flavonoids were collected by blotting seedling roots directly onto cellulose acetate filters. The flavonoids were eluted from filter segments and subsequently analysed by capillary electrophoresis. Effects of various flavonoids on VA-mycorrhiza (VAM) development were studieti. Glomus mosseae and Glomus intraradix (Schenck and Perez, 1990) were used in these studies. Daidzein (2 to 5 µM) increased germination of spores in a period between 15 to 30 days. Myricetin increased hyphal growth of germinated spores at a concentration of 2 µM between 20 and 50 days. Quercetin had a similar effect in a concentration range of 0.8 to 2.0 µM, whereas 5 µM slightly inhibited the growth of hyphae from the germinating spores. Phytoalexin production in VA-mycorrhiza infected legume roots was studied with Vicia faba by wyerone concentration to quantify the reaction of a non-aromatic secondary root metabolite. VAM infected roots increased wyerone concentration by a factor of 3 to 5 compared with the control, however, at a very low absolute level. A phenylpropane-communication concept for Rhizobium infected legumes is discussed in relation to a still incomplete similar scheme for VAM.

Nodulation competitiveness of Rhizobium leguminosarum bv. phaseoli and Rhizobium tropici strains measured by glucuronidase (gus) gene fusion

SummaryThe nodulation competitiveness of 17 Rhizobium leguminosarum bv. phaseoli and 3 R. tropici strains was analysed in growth pouches, at pH 5.2 and 6.4. All 20 strains were coinoculated with a gus+ strain of R. leguminosarum bv. phaseoli strain KIM5s. The gus+ phenotype, carrying the glucuronidase gene, was used to type nodules directly in the growth pouches. Nodule occupancy ranged from 4% for the least competitive to 96% for the most competitive R. leguminosarum bv. phaseoli strain. The R. tropici strains showed low rates of nodule occupancy at pH 6.4 but their competitiveness improved significantly under acid conditions. CIAT 895 was the only R. leguminosarum bv. phaseoli strain that was less competitive (P<0.05) at the lower pH. The competitiveness of all the other R. leguminosarum bv. phaseoli strains was unaffected by pH. Various physiological and genetic properties of the strains were analysed in search of correlations with nodulation competitiveness. Hybridisation patterns with three different DNA probes (nif KDH, common nod genes, and hup genes) and the metabolism of 53 different C sources were compared. No general correlations were found between hybridisation or growth pattern and competitiveness. The less competitive R. tropici strains had a unique DNA hybridisation pattern and were not able to use shikimate, ferulate, coumarate, or asparagine as C sources. Most of the less competitive R. leguminosarum bv. phaseoli strains could not metabolize either ferulate or coumarate. This might indicate a relationship between nodulation competitiveness and the ability to degrade aromatic compounds.

Species dependent uptake and tolerance of nitroaromatic compounds by higher plants

Summary Eleven plant species (five dicotyledonous, six monocotyledonous species) were cultivated for eight weeks in standard soil under identical conditions in the greenhouse. The soil was contaminated with 10, 100 or 500 mg TNT/kg, respectively. Plant roots were extracted using dichloromethane with acid hydrolysis followed by alkalinisation. The main TNT-metabolites measured by GC-ECD were 2-aminodinitrotoluene and 4-aminodinitrotoluene. There was a positive correlation between soil contamination and the concentrations of extractable nitroaromatics in the roots. A species-dependent contamination level of extractable nitroaromatics was shown. In soil supplemented with 10 mg TNT/kg, the highest concentration of all species tested in this soil was found in the roots of Medicago sativa (2.7 μg NAC/g d. wt.). Medicago sativa was not able to grow in soil contaminated with 100 mg TNT/kg, where Triticum aestivum and Phaseolus vulgaris can develop and their roots contain high levels of TNT-metabolites (98 μg NAC/g d.wt. and 91 μg NAC/g d.wt., respectively). In the same soil the lowest level of nitroaromatics was detected in the root extract of Lupinus angustifilius (14 μg/g d. wt.). Only Phaseolus vulgaris was able to grow in the presence of 500 mg TNT/kg soil with very high levels of NACs in the roots (460μg/g d.wt.). General differences between dicotyledonous and monocotyledonous plants in quality or quantity of nitroaromatic compounds were not noticed. Uptake and/or sequestration of nitroaromatics by plants reduce the level of extractable nitroaromatics in the immediate environment of the root (rhizosphere soil). Several cultivars of Triticum aestivum were cultivated in TNT contaminated soil (50 mg TNT/kg) from a former ammunition site. Four of the six cultivars were able to reduce significantly the TNT concentration in the rhizosphere soil.