Phenotypic and Molecular-Phylogenetic Analysis Provide Novel Insights into the Diversity of Curtobacterium flaccumfaciens.

A multiphasic approach was used to decipher the phenotypic features, genetic diversity, and phylogenetic position of 46 Curtobacterium spp. strains isolated from dry beans and other annual crops in Iran and Spain. Pathogenicity tests, resistance to arsenic compounds, plasmid profiling and BOX-PCR were performed on the strains. Multilocus sequence analysis (MLSA) was also performed on five housekeeping genes (i.e., atpD, gyrB, ppk, recA, and rpoB) of all the strains, as well as five pathotype strains of the species. Pathogenicity test showed that six out of 42 strains isolated in Iran were nonpathogenic on common bean. Despite no differences found between pathogenic and nonpathogenic strains in their plasmid profiling, the former were resistant to different concentrations of arsenic, while the latter were sensitive to the same concentrations. Strains pathogenic on common bean were polyphyletic with at least two evolutionary lineages (i.e., yellow-pigmented strains versus red/orange-pigmented strains). Nonpathogenic strains isolated from solanaceous vegetables were clustered within either the strains of C. flaccumfaciens pv. flaccumfaciens or different pathovars of the species. The results of MLSA and BOX-PCR analysis were similar to each other and both methods were able to discriminate the yellow-pigmented strains from the red/orange-pigmented strains. A comprehensive study of a worldwide collection representing all five pathovars as well as nonpathogenic strains of C. flaccumfaciens is warranted for a better understanding of the diversity within this phytopathogenic bacterium

Genotypic Diversity of Iranian strains of Ralstonia solanacearum

During 2007–2009, 170 bacterial isolates were obtained from wilting potato and tomato plants from Iran. Specific polymerase chain reaction (PCR) analyses identified all the isolates as Ralstonia solanacearum. Diversity among the Iranian isolates was determined by a study based on biovar determination, pathogenicity, repetitive sequence PCR and phylotype classification. On the basis of  genotypic, phenotypic and pathogenic characteristics two distinct clusters obtained. Cluster I comprised all biovar 2 isolates and cluster II comprised all biovar N2 (2T) isolates. Phylotype-specifi c multiplex PCR (pmx-PCR) indicated that all biovar 2 and N2 belong to phylotype II. This is the first report of phylotype determination of biovars of R. solanacearum with pmx-PCR in Iran

Phenotypic and genotypic characteristics of Iranian soft rot bacteria isolates from different hosts

During 2005–2006, 42 soft rot bacterial strains were isolated from the infected tubers of potato, roots of carrot, sugar beet and turnip, and the leaves of lettuce and cabbage with soft rot symptoms in Iran. The isolates were rod-shaped, motile with peritrichous flagella, gram negative, facultative anaerobe, oxidase and urease negative and they rotted potato tuber slices. Of the 42 isolates, 20 were identified as Pectobacterium carotovorum subsp. carotovorum (Pcc), 6 as P. carotovorum subsp. odoriferum (Pco), 4 as P. betavasculorum (Pb) and 12 strains as Dickeya dadantii (Dda). PCR amplification of fingerprints of repetitive bacterial DNA elements using the REP, ERIC and BOX primers differentiated the soft rot bacteria to the species and subspecies level. Strains of Pcc and Dda were phenotypically and genotypically highly variable, but Pb and Pco strains had low variability. REP-PCR was found to be a promising genotypic tool for the rapid and reliable speciation and typing of soft rot bacteria

Phenotypic and genotypic characteristics of Iranian soft rot bacteria isolates from different hosts

During 2005–2006, 42 soft rot bacterial strains were isolated from the infected tubers of potato, roots of carrot, sugar beet and turnip, and the leaves of lettuce and cabbage with soft rot symptoms in Iran. The isolates were rod-shaped, motile with peritrichous flagella, gram negative, facultative anaerobe, oxidase and urease negative and they rotted potato tuber slices. Of the 42 isolates, 20 were identified as Pectobacterium carotovorum subsp. carotovorum (Pcc), 6 as P. carotovorum subsp. odoriferum (Pco), 4 as P. betavasculorum (Pb) and 12 strains as Dickeya dadantii (Dda). PCR amplification of fingerprints of repetitive bacterial DNA elements using the REP, ERIC and BOX primers differentiated the soft rot bacteria to the species and subspecieslevel. Strains of Pcc and Dda were phenotypically and genotypically highly variable, but Pb and Pco strains had low variability. REP-PCR was found to be a promising genotypic tool for the rapid and reliable speciation and typing of soft rot bacteria

Genotypic Diversity of Iranian strains of <I>Ralstonia solanacearum</I>

During 2007–2009, 170 bacterial isolates were obtained from wilting potato and tomato plants from Iran. Specific polymerase chain reaction (PCR) analyses identified all the isolates as Ralstonia solanacearum. Diversity among the Iranian isolates was determined by a study based on biovar determination, pathogenicity, repetitive sequence PCR and phylotype classification. On the basis of  genotypic, phenotypic and pathogenic characteristics two distinct clusters obtained. Cluster I comprised all biovar 2 isolates and cluster II comprised all biovar N2 (2T) isolates. Phylotype-specifi c multiplex PCR (pmx-PCR) indicated that all biovar 2 and N2 belong to phylotype II. This is the first report of phylotype determination of biovars of R. solanacearum with pmx-PCR in Iran

Effective combination of arugula vermicompost, chitin and inhibitory bacteria for suppression of the root-knot nematode Meloidogyne javanica and explanation of their beneficial properties based on microbial analysis.

Root-knot nematodes (Meloidogyne spp.) are dangerous parasites of many crops worldwide. The threat of chemical nematicides has led to increasing interest in studying the inhibitory effects of organic amendments and bacteria on plant-parasitic nematodes, but their combination has been less studied. One laboratory and four glasshouse experiments were conducted to study the effect on M. javanica of animal manure, common vermicompost, shrimp shells, chitosan, compost and vermicompost from castor bean, chinaberry and arugula, and the combination of arugula vermicompost with some bacteria, isolated from vermicompost or earthworms. The extract of arugula compost and vermicompost, common vermicompost and composts from castor bean and chinaberry reduced nematode egg hatch by 12-32% and caused 13-40% mortality of second-stage juveniles in vitro. Soil amendments with the combination vermicompost of arugula + Pseudomonas. resinovorans + Sphingobacterium daejeonense + chitosan significantly increased the yield of infected tomato plants and reduced nematode reproduction factor by 63.1-76.6%. Comparison of chemical properties showed that arugula vermicompost had lower pH, EC, and C/N ratio than arugula compost. Metagenomics analysis showed that Bacillus, Geodermatophilus, Thermomonas, Lewinella, Pseudolabrys and Erythrobacter were the major bacterial genera in the vermicompost of arugula. Metagenomics analysis confirmed the presence of chitinolytic, detoxifying and PGPR bacteria in the vermicompost of arugula. The combination of arugula vermicompost + chitosan + P. resinovorans + S. daejeonense could be an environmentally friendly approach to control M. javanica

Effective combination of arugula vermicompost, chitin and inhibitory bacteria for suppression of the root-knot nematode Meloidogyne javanica and explanation of their beneficial properties based on microbial analysis

Root-knot nematodes (Meloidogyne spp.) are dangerous parasites of many crops worldwide. The threat of chemical nematicides has led to increasing interest in studying the inhibitory effects of organic amendments and bacteria on plant-parasitic nematodes, but their combination has been less studied. One laboratory and four glasshouse experiments were conducted to study the effect on M. javanica of animal manure, common vermicompost, shrimp shells, chitosan, compost and vermicompost from castor bean, chinaberry and arugula, and the combination of arugula vermicompost with some bacteria, isolated from vermicompost or earthworms. The extract of arugula compost and vermicompost, common vermicompost and composts from castor bean and chinaberry reduced nematode egg hatch by 12–32% and caused 13–40% mortality of second-stage juveniles in vitro. Soil amendments with the combination vermicompost of arugula + Pseudomonas. resinovorans + Sphingobacterium daejeonense + chitosan significantly increased the yield of infected tomato plants and reduced nematode reproduction factor by 63.1–76.6%. Comparison of chemical properties showed that arugula vermicompost had lower pH, EC, and C/N ratio than arugula compost. Metagenomics analysis showed that Bacillus, Geodermatophilus, Thermomonas, Lewinella, Pseudolabrys and Erythrobacter were the major bacterial genera in the vermicompost of arugula. Metagenomics analysis confirmed the presence of chitinolytic, detoxifying and PGPR bacteria in the vermicompost of arugula. The combination of arugula vermicompost + chitosan + P. resinovorans + S. daejeonense could be an environmentally friendly approach to control M. javanica