Pseudomonas Avenae Research Articles

Biology of Rice Bacterial Brown Stripe Pathogen and Integrated Strategies for Its Management

Rice (Oryza sativa L.) is most commonly cultivated food grain crop in India as well as over the world. Rice is susceptible to many destructive diseases, among them bacterial diseases reported to major constrain in their production which causes significant yield loss. Major bacterial diseases affecting their viz., Bacterial leaf blight (BLB) (Xanthomons oryzae pv. oryzae), bacterial leaf streak (BLS) (Xanthomonas oryaze pv. oryzacola) and bacterial panicle blight (BPB) (Burkholderia glumae) and Bacterial Brown stripe (BBS) (Pseudomonas avenae) are of regular occurrence. On the basis of diseases severity and economic losses BPB, BLB and BLS are most destructive respectively reported by many researchers. Management of such disease is a challenge without harming environment and human health. Chemicals having adverse effect on natural ecosystem and not economically feasible. In this review management of such diseases by eco-friendly approach is discussed. Adopting such practices is helpful in maintaining cost benefit ratio by resulting in profit. These practices can reduce the harmful residual effect of the chemical. It also suggests at about adopting effective cultural and physical method.

Agronomic characteristics and management of diseases in maize with chelate-based products containing calcium, copper, manganese, and zinc

The aim of this work was to verify the potential of chelate-based products containing calcium, copper, manganese, and zinc for the management of Pantoea ananatis, Puccinia polysora, Cercospora zeae-maydis, Exserohilum turcicum, Diplodia macrospora, and Pseudomonas avenae in crop maize growth in the summer season, as well as their influence on agronomic characteristics. The treatments included commercial chelate-based products of amino acids with the elements calcium (15%), copper (5%), manganese (15%), and zinc (10%) at doses of 0.5 kg ha-1, 0.3 L ha-1, 0.4 kg ha-1, and 1 L ha-1, respectively; fungicides (20% azoxystrobin and 8% cyproconazole at a dose of 0.3 L ha-1 + 25% propiconazole at a dose of 0.4 L ha-1); and water. The tests were carried out under field conditions for two consecutive years with two simple hybrids. The plant height, stem diameter, number of rows per ear, number of grains per ear row, productivity and mass of one thousand grains, as well as the severity of leaf diseases, were all evaluated, and chemical analysis of the leaves was performed. In the 2016/2017 growth season, for the number of rows per ear and number of grains per row, the fungicide treatment showed the highest values, whereas for the mass of one thousand grains and productivity, the chelate treatments did not differ from the fungicide treatment and were different from the water treatment. In the 2017/2018 growth season, for the mass of one thousand grains and yield, only the fungicide treatment was different from the water treatment. For all the chelates studied for both hybrids, there was no difference in nutrient content before and after foliar application. It can be concluded that calcium, copper, manganese, and zinc products may influence agronomic traits but not the severity of the diseases evaluated in these two hybrids of maize under the edaphoclimatic conditions in which the study was carried out.

Validation of a diagrammatic scale for quantification of bacterial leaf blight (causal agent Pseudomonas avenae) in maize

Bacterial leaf blight occurs in almost the entire Brazilian territory and can cause significant economic damage. However, its effects can be curtailed with the following tools that aid in quantification for carrying out the best severity assessment that can be applied to the studies used in its control. The objective of this study was to develop and validate a diagrammatic scale to quantify the severity of bacterial leaf blight in maize caused by Pseudomonas avenae. Corn leaves were collected with different levels of disease severity, and the total leaf area as well as the injured area of the middle third of each leaf was measured. From this, the minimum and maximum limits of the disease and, subsequently, four intermediate levels were determined whilst taking into account the law of visual stimulus of Weber-Fechner. Levels 1.5%, 2.5%, 9%, 18%, 46%, and 70% were selected with validation performed by eight evaluators, four inexperienced and four experienced. These evaluators estimated the severity values, initially without the use of the proposed diagrammatic scale and in a second attempt with the use of the scale. We concluded that it was possible to improve the accuracy and precision of the evaluators when they used the scale as a tool to assess the severity of bacterial leaf blight on corn leaves.

Validation of a diagrammatic scale for quantification of bacterial leaf blight (causal agent Pseudomonas avenae) in maize

Bacterial leaf blight occurs in almost the entire Brazilian territory and can cause significant economic damage. However, its effects can be curtailed with the following tools that aid in quantification for carrying out the best severity assessment that can be applied to the studies used in its control. The objective of this study was to develop and validate a diagrammatic scale to quantify the severity of bacterial leaf blight in maize caused by Pseudomonas avenae. Corn leaves were collected with different levels of disease severity, and the total leaf area as well as the injured area of the middle third of each leaf was measured. From this, the minimum and maximum limits of the disease and, subsequently, four intermediate levels were determined whilst taking into account the law of visual stimulus of Weber-Fechner. Levels 1.5%, 2.5%, 9%, 18%, 46%, and 70% were selected with validation performed by eight evaluators, four inexperienced and four experienced. These evaluators estimated the severity values, initially without the use of the proposed diagrammatic scale and in a second attempt with the use of the scale. We concluded that it was possible to improve the accuracy and precision of the evaluators when they used the scale as a tool to assess the severity of bacterial leaf blight on corn leaves.

Comparative genome‐wide analysis of codon usage of different bacterial species infecting Oryza sativa

Oryza sativa is vastly affected by microbial pathogen, causing blight-related diseases, which in turn deplete the growth and productivity of rice. In this study, we analyzed four bacterial rice pathogen genomes and reported on their codon usage that might have greater implication in mutation-related research. Differential codon usage indices, such as codon adaptation index (CAI), codon bias index (CBI), effective number of codons (ENc), relative synonymous codon usage (RSCU), correspondence analysis (COA), and parity plots, were applied on coding sequences of Pseudomonas fuscovaginae, Pseudomonas syringae, Xanthomonas oryzae, and Pseudomonas avenae speices. The RSCU results proposed a high-frequency usage of CUG and CGC that codes for leucine and arginine in all of the species. The CBI and CAI values between the genomes range from 0.17 to 0.3 and from 0.26 to 0.35, respectively, indicating a direct proportionality between these indexes. The mean ENc value of P. avenae coding sequence showed high codon bias compared with other genomes. The axis I variation from COA analysis shows a mean value of 42.28% codon variations in these bacterial species. Correlation studies between axis I and ENc-GC3, along with CAI and CBI, suggested the presence of nucleotide bias and mutational pressure as major forces for codon bias within these species. Hence, certain genes with high CAI-CBI have been correlated for better gene expression. Our study highlights the importance of nucleotide biasness, mutation pressure, and natural selection in shaping protein-coding genes in these four rice-affecting bacteria. This would further help in investigating the evolution of pathogenic gene families, which may direct research toward synthetic genes that could be suppressed or overrepresented based on their codon usage pattern toward pathogenicity.

NE-EDRsu1 and NE-EDRbt1, Disease-resistant Sweet Corn Populations with sugary1 and brittle1 Endosperms

perate and one-half tropical sweet corn, the latter derived from tropical field corns (Brewbaker, 1978). The tropical parents were chosen for their resistance to important diseases (Brewbaker, 1979). These include the seedling, stalk, and kernel rots caused by Fusarium moniliforme Sheld., and maize mosaic virus (MMV) and maize dwarf mosaic virus (MDMV). Tropical lines also incorporate racially nonspecific tolerance of common rust, southern rust, bacterial leaf blight, northern leaf blight, brown spot, and southern leaf blight. Causal agents are Puccinia sorghi Schw., Puccinia polysora Underw., Pseudomonas avenae Mains, Exserohilum turcicum (Pass.) Leonard & Suggs, Physoderma maydis

Identification of novel genes differentially expressed in compatible and incompatible interactions between rice and Pseudomonas avenae

Establishment of a plant–pathogen interaction involves differential gene expression in both organisms. To isolate rice genes induced during either compatible or incompatible interactions, we performed a comparative analysis of expression patterns in cultured rice cells, inoculated with either compatible or incompatible strains of Pseudomonas avenae, by fluorescence differential display (FDD). Using 52 sets of arbitrary primer combinations, two cDNAs ( IAI1 and IAI2) expressed in incompatible strain-inoculated rice cells and one cDNA ( CAI1) expressed in compatible strain inoculated cells, were identified. A hydropathy profile revealed that the IAI1 protein spans the membrane at a putative transmembrane domain. The deduced amino acid sequence of IAI2 shares considerable homology with Bowman–Birk proteinase inhibitors over the majority of the sequence. The deduced CAI1 protein is rich in glycine, containing a putative signal peptide with a potential cleavage site, suggesting its membership in the glycine-rich protein (GRP) family. GRPs are thought to be structural cell wall proteins. When a GFP fusion with the CAI1 gene was introduced into onion cells by bombardment, green fluorescence of the cell wall was observed. These data suggest that CAI1 is involved in the repair of cell wall injuries by the compatible strain of P. avenae.

Isolation and Characterization of the algD gene of Pseudomonas syringae pv. phaseolicola and its distribution among other Pseudomonads and related Organisms

The gene coding for GDP‐mannose dehydrogenase (algD) was isolated from a Pseudomonas syringae pv. phaseolicola genomic library using a polymerase chain reaction‐generated heterologous DNA‐probe from Pseudomonas aeruginosa. A total of 2123 base pairs were sequenced (accession number AF001555) and analysed for homologies to the alginate gene cluster of P. aeruginosa. Downstream from algD an alg8 homologue was found suggesting a similar arrangement of the alginate gene cluster in P. syringae pv. phaseolicola to that in P. aeruginosa. Also, the deduced amino acid sequence of algD shows high similarity to that of P. aeruginosa (0.9) and Azotobacter vinelandii (0.88). Southern hybridization experiments revealed that algD is widely distributed among members of the Pseudomonas rRNA homology group I. Among others, sequences homologous to algD were detected in the P.syringae pathovars lachrymans, mori, morsprunorum,pisi, savastanoi, tabaci and tomato as well as in Pseudomonas amygdali. For most of the algD positive organisms synthesis of alginate has been reported by other studies. However, algD homologues were also detected for the species Pseudomonas corrugata, Pseudomonas marginalis and Pseudomonas avenae (Acidovorax avenae), for which alginate biosynthesis has not yet been reported.

Flagellin from an Incompatible Strain of Pseudomonas avenae Induces a Resistance Response in Cultured Rice Cells

The host range of Pseudomonas avenae is wide among monocotyledonous plants, but individual strains can infect only one or a few host species. The resistance response of rice cells to pathogens has been previously shown to be induced by a rice-incompatible strain, N1141, but not by a rice-compatible strain, H8301. To clarify the molecular mechanism of the host specificity in P. avenae, a strain-specific antibody that was raised against N1141 cells and then absorbed with H8301 cells was prepared. When a cell extract of strain N1141 was separated by SDS-polyacrylamide gel electrophoresis and immunostained with the N1141 strain-specific antibody, only a flagellin protein was detected. Purified N1141 flagellin induced the hypersensitive cell death in cultured rice cells within 6 h of treatment, whereas the H8301 flagellin did not. The hypersensitive cell death could be blocked by pretreatment with anti-N1141 flagellin antibody. Furthermore, a flagellin-deficient N1141 strain lost not only the induction ability of hypersensitive cell death but also the expression ability of the EL2 gene, which is thought to be one of the defense-related genes. These results demonstrated that the resistance response in cultured rice cells is induced by the flagellin existing in the incompatible strain of P. avenae but not in the flagellin of the compatible strain.

Biochemical and Morphological Features of Rice Cell Death Induced by Pseudomonas avenae

Pseudomonas avenae is a Gram-negative phytopathogenic bacterium that causes the symptom of a brown stripe in infected susceptible plants. The host range of P. avenae is wide among the monocotyledonous plants, however, individual strains can infect only one or a few host species. A rice-incompatible strain, N1141, caused rapid cell death in sheath sections and in cultured rice cells. A rice-compatible strain, H8301, also induced cell death, however, this cell death in a compatible interaction was delayed compared to the cell death induced by the N1141 incompatible strain. Inoculation of N1141 strain induced expression of EL2 gene which is thought to be one of the defense-related gene. Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) of cultured rice cells showed that DNA cleavage occurred only in N1141-inoculated rice cells. N1141 strain caused cytoplasmic condensation, shrinkage, and plasma membrane blebbing, all of which are important morphological characteristics of programmed cell death (PCD). In contrast, H8301 strain inoculated rice cells appeared to show weakening of the cell wall instead of cytoplasm condensation, shrinkage and membrane blebbing. These results suggest that the rapid cell death of rice induced by the incompatible strain is characterized as PCD.

Transformation of pBR322-Derived Plasmids in PhytopathogenicPseudomonas avenae and Enhanced Transformation in ItsProline-Auxotrophic Mutant

Efficient transformation of pBR322 and its derivedplasmids, which have been widely used as cloning vectors in Escherichiacoli, was observed in Pseudomonas avenae (K1), the pathogen ofleaf blight disease in cereals. Moreover, there was a 10- to 50-foldtransformation efficiency (1.3-3.0 x 10(6)/&mgr;g DNA) in theproline-auxotrophic mutant (Pr47), whose virulence to rice seedlingsdecreased. Similar enhancement of the frequency of transfer by mobilizationof RSF1010, a broad host range plasmid, was observed in the recipient Pr47strain in mating with donor Pseudomonas syringae. The plasmidsharbored in these strains were maintained very stably after subcultures.Thus, a highly efficient transformation system with pBR322-derived plasmidsused as a vector and Pseudomonas as a host bacterium was developed.

Bacterial Diseases of Rice. II. Characterization of Pathogenic Bacteria Associated with Sheath Rot Complex and Grain Discoloration of Rice in the Philippines

From over 5,600 bacteria isolated from rice plants with sheath rot complex and grain discoloration syndrome, and two batches of 1 kg of rice seed (cultivars IR54 and IR8866), 204 pathogens were initially characterized by phenotypic tests, serology, and growth on selective media, and further distinguished by API 20NE, Biolog, and cellular fatty acid methyl esterfingerprints. The best differentiation was obtained by the Biolog system. The nonfluorescent pathogens were represented by clusters D1 (Burkholderia glumae, formerly Pseudomonas glumae) and E (Acidovorax avenae subsp. avenae, formerly Pseudomonas avenae). Seven clusters were distinguished among the fluorescent strains associated with sheath rot complex and grain discoloration. Cluster A5 was identified as Pseudomonas aeruginosa, and cluster B1 as P. fuscovaginae. Cluster B2 is related to Pseudomonas aureofaciens, P. corrugata, P. fluorescens, and P. marginalis. Clusters B1 and B2 were only slightly different. The strains identified as P. fuscovaginae were different from the type strains in 2-ketogluconate production.

Detection of a Protein Specific to the Strain of Pseudomonas avenae Manns 1909 Pathogenic to Rice.

Detection of a Protein Specific to the Strain of Pseudomonas avenae Manns 1909 Pathogenic to Rice.

イネ褐条病細菌（Ｐｓｅｕｄｏｍｏｎａｓ ａｖｅｎａｅ）の分類学的検討

イネ褐条病細菌（Ｐｓｅｕｄｏｍｏｎａｓ ａｖｅｎａｅ）の分類学的検討

Studies on the Infection Cycle and Control of Bacterial Brown Stripe of Rice Caused by Pseudomonas avenae

Studies on the Infection Cycle and Control of Bacterial Brown Stripe of Rice Caused by Pseudomonas avenae

Transfer of several phytopathogenic Pseudomonas species to Acidovorax as Acidovorax avenae subsp. avenae subsp. nov., comb. nov., Acidovorax avenae subsp. citrulli, Acidovorax avenae subsp. cattleyae, and Acidovorax konjaci.

DNA-rRNA hybridizations, DNA-DNA hybridizations, polyacrylamide gel electrophoresis of whole-cell proteins, and a numerical analysis of carbon assimilation tests were carried out to determine the relationships among the phylogenetically misnamed phytopathogenic taxa Pseudomonas avenae, Pseudomonas rubrilineans, "Pseudomonas setariae," Pseudomonas cattleyae, Pseudomonas pseudoalcaligenes subsp. citrulli, and Pseudomonas pseudoalcaligenes subsp. konjaci. These organisms are all members of the family Comamonadaceae, within which they constitute a separate rRNA branch. Only P. pseudoalcaligenes subsp. konjaci is situated on the lower part of this rRNA branch; all of the other taxa cluster very closely around the type strain of P. avenae. When they are compared phenotypically, all of the members of this rRNA branch can be differentiated from each other, and they are, as a group, most closely related to the genus Acidovorax. DNA-DNA hybridization experiments showed that these organisms constitute two genotypic groups. We propose that the generically misnamed phytopathogenic Pseudomonas species should be transferred to the genus Acidovorax as Acidovorax avenae and Acidovorax konjaci. Within Acidovorax avenae we distinguished the following three subspecies: Acidovorax avenae subsp. avenae, Acidovorax avenae subsp. cattleyae, and Acidovorax avenae subsp. citrulli. Emended descriptions of the new taxa are presented.

Serological Properties and Specificity of Pseudomonas avenae Manns 1909, the Causal Agent of Bacterial Brown Stripe of Rice.

Serological Properties and Specificity of Pseudomonas avenae Manns 1909, the Causal Agent of Bacterial Brown Stripe of Rice.

Demonstration of synonymy between the plant pathogens Pseudomonas avenae and Pseudomonas rubrilineans

Strains of Pseudomonas avenae Manns 1909 and Pseudomonas rubrilineans ( Lee et al., 1925 ) Stapp 1928 were compared using physiological, biochemical and serological tests together with an examination of plant host range. Minor differences were found between the physiological and biochemical characteristics of the two pathogens, while no differences were detected in pathogenicity, host range, cellular protein profiles, direct fluorescent straining, and dot-immunobinding assays. P. avenae and P. rubrilineans were distinctly different from other non-fluorescent pseudomonads. We were unable to differentiate P. avenae strains from those of P. rubrilineans, and we propose that they be regarded as a single species, retaining the name Pseudomonas avenae.

Characteristics of Pseudomonas spp. Causing Grain Discoloration and Sheath Rot of Rice, and Associated Pseudomonad Epiphytes

Ninety-five strains of fluorescent (presumed to be Pseudomonas spp.) and nonfluorescent pathogens of rice causing grain and sheath rot, dirty panicle, and manchado de grano, and 21 strains of nonpathogenic fluorescent pseudomonads isolated from rice grain and sheaths from 22 countries were compared with 26 reference strains (Pseudomonas avenae, P. fuscovaginae, P. glumae, P. marginalis, and P. syringae) with the use of morphology, serology and 77 physological traits. A Ward's minimum variance cluster analysis grouped the strains into seven clusters corresponding to six bacterial species: P. fuscovaginae (two clusters), P. avenae, P. fluorescens, P. glumae, P. putida, and P. syringae (...)

R-body-producing bacteria.

Until 10 years ago, R bodies were known only as diagnostic features by which endosymbionts of paramecia were identified as kappa particles. They were thought to be limited to the cytoplasm of two species in the Paramecium aurelia species complex. Now, R bodies have been found in free-living bacteria and other Paramecium species. The organisms now known to form R bodies include the cytoplasmic kappa endosymbionts of P. biaurelia and P. tetraurelia, the macronuclear kappa endosymbionts of P. caudatum, Pseudomonas avenae (a free-living plant pathogen), Pseudomonas taeniospiralis (a hydrogen-oxidizing soil microorganism), Rhodospirillum centenum (a photosynthetic bacterium), and a soil bacterium, EPS-5028, which is probably a pseudomonad. R bodies themselves fall into five distinct groups, distinguished by size, the morphology of the R-body ribbons, and the unrolling behavior of wound R bodies. In recent years, the inherent difficulties in studying the organization and assembly of R bodies by the obligate endosymbiont kappa, have been alleviated by cloning and expressing genetic determinants for these R bodies (type 51) in Escherichia coli. Type 51 R-body synthesis requires three low-molecular-mass polypeptides. One of these is modified posttranslationally, giving rise to 12 polypeptide species, which are the major structural subunits of the R body. R bodies are encoded in kappa species by extrachromosomal elements. Type 51 R bodies, produced in Caedibacter taeniospiralis, are encoded by a plasmid, whereas bacteriophage genomes probably control R-body synthesis in other kappa species. However, there is no evidence that either bacteriophages or plasmids are present in P. avenae or P. taeniospiralis. No sequence homology was detected between type 51 R-body-encoding DNA and DNA from any R-body-producing species, except C. varicaedens 1038. The evolutionary relatedness of different types of R bodies remains unknown.