seyed mohsen taghavi

So far, several bacterial diseases, including wheat stripe spots caused by Xanthomonas translucens and mild bacterial mosaics caused byClavibacter tessellarius , have been reported in Poaceae family plants. In recent years, reports have been published on the presence of Clavibacter zhangzhiyongii bacteria in barley plants in some countries, such as Australia and China. This research was conducted to track and identify the mentioned bacteria using biochemical and molecular methods and determining its host range. For this purpose, in the years 2021 and 2022, wheat, barley, and weeds with symptoms of brown spots, mild mosaic, decay, and yellowing of leaves were sampled in the provinces of Golestan, Bushehr, Qazvin, Zanjan, and Fars. Bacterial isolation was performed according to standard bacteriological methods. Phenotypic and biochemical tests identified isolates and housekeeping genes atpD, gyrB, ppK, and recA. Pathogenicity tests were performed by spraying and stem injection. Based on biochemical and molecular tests, 15 isolates of the genus Clavibacter were identified, and among the studied isolates, three isolates were identified as C. zhangzhiyongii.

As a consequence of the abundant use of copper bactericides, some species of plant pathogenic bacteria, including Xanthomonas citri pv. citri (Xcc), have developed resistance to copper. This study evaluates pathological phenotypes and in vitro efficiency of prevalent copper compounds in inhibiting Xcc. Sampling was conducted across citrus orchards during 2021-2022. One hundred and seventeen citrus orchards were surveyed and 132 strains identified as Xanthomonas citri pv. citri based on phenotypic and genotypic characteristics. Different pathogenic phenotypes were observed by inoculating the representative strains on different cultivars of lime, orange, citrumelo and grapefruit, but tangerine cultivars did not show disease symptoms. All the strains showed an intermediate level of sensitivity and grew in the medium containing 100 and 150 mg/l of copper sulfate. In addition higher concentrations (250, 300, 350 and 400 mg/liter) showed inhibition rate more than 90%. Copper carboxylate at the concentration of 0.75 g/liter prevented the growth of more than 85% of the strains. Also, Copper oxychloride showed the best inhibition rate in concentrations higher than 3 g/liter. 1.5 ml/liter of Bordeaux mixture controlled more than 80% of the strains. None of copper resistance gene clusters copLAB and copABCD were detected in tested Xanthomonas citri strains. The proper characterization of pathological phenotypes and sensitivity to copper leads more confident decisions in citrus canker disease management.

The plant growth promoting bacteria (PGPB) inhabiting the phyllosphere of different plants provides a tool for more efficient use of bacteria as a source of biofertilizers. The use of molecular technologies leads to in-depth research of the phyllosphere microorganisms and may provide new avenues for the development and validation of modern agricultural operations and significantly increase productivity. The aim of this research was to investigate the plant growth promoting (PGP) traits of bacteria isolated from maize (Zea mays L.) phyllosphere cultivated in different geographical zones of country (Iran) and their molecular identification by 16Sr RNA sequencing.

In September (2016), 116 samples of healthy mature leaves were collected from the maize fields located in 6 provinces of Iran (Fars, Alborz, Qazvin, Khuzestan, Tehran and Khorasan) and then, phyllosphere bacteria were isolated from them. Growth promoting traits of bacteria including Indole-3 Acetic acid (IAA) production, organic phosphate dissolution, siderophore production, exopolysaccharides (EPS) production and also nitrogenase enzyme activity were measured using standard methods. Superior strains were identified based on 16S rRNA sequencing method.

The 10 from 242 bacterial strains isolated from maize phyllosphere were selected based on their growth promoting traits. All strains selected demonstrated nitrogenase activity, organic phosphate dissolution and IAA and EPS production capability. The highest nitrogenase activity (70.31 nM ml-1 h-1) and organic phosphate dissolution (75.05 g l-1) were observed in THE15 strain, while the lowest amount of these properties belonged to KHO57 (5.55 nM ml-1 h-1) and KHO51 (15.90 g l-1) strains, respectively. The QAZ26 and TEH15 strains had the highest amount of IAA production (31.56 and 30.00 µg ml-1, respectively) and the ALB32 strain produced the lowest amount of IAA (4.50 µg ml-1). The EPS production by strains ranged from 0.120 to 1.805 g l-1. Among the strains investigated, only KUU32, KHU53, ALB32 and QAZ26 were able to produce siderophore. 16S rRNA sequencing revealed that the 10 strains selected belong to Bacillus, Microbacterium, Pseudarthrobacter, Pseudomonas, Stenotrophomonas, Enterobacter and Kocuria genera. The Bacillus with 4 different species (including Bacillus subtilis, Bacillus megaterium, Bacillus paralicheniformis and Bacillus pumilus) was the most dominant genus.

Based on the results of this study, Bacillus was the most dominant genus of plant growth promoting bacteria in the maize phyllosphere. Among the isolated bacteria, Enterobacter hormaechei TEH15 was highly capable of nitrogenase enzyme activity, IAA and organic phosphate solubility. Therefore, this strain deserves further research in greenhouse and field studies of maize cultivation and maize family plants.

Citrus bacterial canker is an economically important disease in many tropical and subtropical countries and caused by Xanthomonas citri subsp. citri. Several pathotypes of this pathogen have been described that primarily distinguished by their geographical origin, host range and certain genotypic characteristics Leaves, fruits and twinges samples of ‘Mexican 'lime, with bacterial canker symptoms were collected from Kohgiluyeh and Boyer-Ahmad province in 2012. The bacterial strains were isolated from infected tissues using classic methods and primary identification of bacterial isolates was performed based on phenotypic characterization. Pathogenicity of isolates was approved on leaves of Mexican lime. Based on the disease symptoms, phenotypic and pathogenicity tests, PCR test by using specific primers and sequencing data of histidine kinase gene, the isolates were identified as Xanthomonas citri subsp. citri. This is the first report of the disease and the causal bacterium in Kohgiluyeh and Boyer-Ahmad province.

The isolation of native microorganism that produced biosurfactants in order to oil pollutants bioremediation and hydrophobic oil hydrocarbons availability inter soil texture has become important issues in bioremediation technology. Surfactin is one of the biosurfactants with more application that produced by Bacillus subtilis strains could overcome these problems. Thus in this study, we investigated operon which involved in surfactin biosynthesis and its regulator comQXPA operon due to a high level of surfactin biosynthesis by B. subtilis MJ01 isolated from oil contaminated soil based on comparative genomics approaches. Surfactin operon localized and compared among six genomes of close relative strains and MJ01 indicated that missense point mutations on genes of surfactin operon were existence. These mutations affected NPRS protein AMP-binding domain that responsible to bind amino acid to correct the situation on surfactin peptide ring. It seems that lack of hemolytic and anti-microbial function of MJ01 surfactin was due to the creation of missense mutation and modifications in the surfactin biosynthesis NPRS enzyme structure. Moreover, srf genes expression regulated by comQXPAþ quorum sensing operon. MJ01 Quorum sensing operon rearrangement showed that part of the comQ gene was extended into comX gene and these genes had overlap region. Results suggested that in MJ01 genome has been occurred specific combination of QS genes organization. Despite high similarity of three genes comQXPþ among MJ01 with BEST7613 and other subtilis strains group, comA gene showed high identity with spizizenii strains groupþ.

During 2010 and 2011, 24 Xanthomonas strains were isolated from infected walnut trees from different regions of Fars and Lorestan provinces. For investigation of phenotypic and genotypic features, physiological, biochemical tests and rep-PCR with BOX, ERIC and REP primers. Isolates were rod-shaped, motile with polar flagella, gram negative, obligate parasite, oxidative negative, catalase positive and hydrolyzed esculin. All isolates produced H2S from cystein and acid from glucose, sucrose, D-mannose and D-sorbitol. Isolates showed differences in some characteristics such as tween 80 hydrolysis, starch hydrolysis, tolerance to 3% Nacl and utilization of L-alanin. Also pathogenicity tests and antibiogram were carried out. Based on phenotypic features, pathogenicity tests and amplification of 413 bp fragment with rev_seq R and rev_seq f primers in PCR assay, the isolates were identified as Xanthomonas arboricola pv. juglandis. Based on numerical analysis of phenotypic features most of the isolates were homogeneous and had about 87% similarity. The isolates divided into two groups on the basis of rep-PCR with BOX, ERIC and REP primers. Rep-PCR with above mentioned primers did not confirm clustering of theses isolates based on geographic origin. This is the first report of bacterial blight disease of walnut in Fars province of Iran.

Bacterial wilt caused by Ralstonia solanacearum is one of the most destructive disease which negatively affects the tomato production worldwide. Considering the importance of the disease, searching for resistant varieties and using biological control agents could be effective approaches in reducing the damage of the pathogen. In this study, the cultivars including Super CH, falat-111, Peto, Falkata, Queen and Early Urbana were studied. The experiments were conducted with completely randomized factorial design with a disease factor in two levels as inoculated and not inoculated. Seven cultivars (treatments) with four replicates were evaluated. Statistical analysis were performed using SAS software. The antagonistic strains of Bacillus subtilis B7, Pseudomonas flourecsens CHAO and Trichoderma harzianum T.BI and mobil cultivar were utilized. In vitro anti-bacterial evaluations were conducted and T. harzianum T.BI and B. subtilis B7 showed 3 and 5 mean distance of inhibition zone respectively but P fluorescens CHAO showed no inhibition effects. The results of means comparison showed that the stem length of cultivar Queen had the lowest reduction while the highest reduction in stem length was related to the cultivar early urbana. Regarding the fresh weight, the minimum reduction was related to cv Queen while the maximum ones were relevant to cvs Super CH, falat and Falkata cultivars. Moreover, the minimum decrease of dry weight was associated with the Queen cultivar.The results of using antagonists showed that T. harzianum T.BI and B. subtilis B7 regarding index of stem length, shoot and root fresh weight, dry weight of roots and shoots are the best options to control bacterial wilt.

In 2010- 2012 surveys, witches''- boom disease of tomato was observed in Borazjan area (Bushehr province, Iran). Agent of the disease was transmitted from tomato to tomato and eggplant by grafting and to Madagascar periwinkle via dodder inoculation, inducing phytoplasma-type symptoms in inoculated plants. Presence of phytoplasma in naturally affected tomatoes and all symptomatic graft and dodder inoculated plants was confirmed by direct and nested polymerase chain reaction (PCR) using primer pairs P1/P7 and R16F2n/R16R2. BLAST search and phylogenetic analysis of 16SrDNA showed that detected phytoplasma belonged to peanut witches''- broom (16SrII) group. Phylogenetic analysis, percent homology and virtual RFLP indicated that, as a member of 16SrII group, Borazjan tomato witches’- broom (BTWB) phytoplasma together with Bushehr eggplant and alfalfa witches’- broom (BEWB and BAWB, respectively) phytoplasmas were classified with Candidatus Phytoplasma australasia, a phytoplasma related to 16SrII-D subgroup. Based on the same analysis, BTWB, BEWB and BAWB phytoplasmas were differentiable from three other Iranian 16SrII related phytoplasmas associated with alfalfa witches''- broom diseases in Yazd and Fars provinces and lime witches''- broom disease in southern Iran.This is the first report of tomato witches''- broom disease and characterization of its associated phytoplasma in Iran.

Winter jasmine, Jasminum nudiflorum, is a tree belonging to Syringa family, which is used in the urban designing. The gall disease in the tree branches caused by Pseudomonas savastanoi is one of the most important diseases in this trees The purpose of this study was to determine the phenotypic and genotypic diversity of P. savastanoi using the BOX PCR.
This experimental study was performed on 23 P. savastanoi isolated from winter Jasmine, Shiraz, Fars, Iran. A IAAL primer and PCR approach was used to direct tracking of the strains. The genotypic characteristics of the P. savastanoi isolates was performed by rep-PCR using BOX primers. The data were next analysed using NTsys-PC software.
Base in numerical analysis of phenotypic characteristics, the strains showed 88% similarity to each other. Using IAAL primer and GES buffer obtained from gall extract, DNA fragments with 454 bp length were amplified. Using rep-PCR option and BOX primer in NTsys-pc software, it was shown that the isolates can be divided into three cluster with 81% similarity. These clusters belonged to Shiraz’s Winter Jasmine isolates, Tehran’s Oleander isolate and Tehran’s Olive as well as standard isolate.
On the basis of our findings, using BOX-PCR it is possible to differentiate the P. savastanoi isolated from different geographical areas and different hosts. Furthermore, this is the first report of direct detection of P. savastanoi from gall using PCR in Iran.