r. khakvar

Entomogenous fungi include a wide range of species that are ecologically very diverse. Many of them are pathogenic to insects and mostly show host specificity. Isolation and identification of native entomogenous fungi, especially pathogenic species, and their use as a source of biological control agents is an important safe, environmentally-friendly pest control approach. This survey isolated and characterized entomogenous fungi that naturally occur in soil. Post-harvest infestations cause considerable losses in cereal production. Stored-product insect control is mainly accomplished by chemical means; however, pesticides can affect non-target species, such as plants, animals, and humans. Pesticides increase pest resistance. Another possible negative effect of pesticides is their ability to bioaccumulate and biological magnification. Therefore, alternative agents are needed for managing stored-product insect pests. Biological control of stored-product insects with entomopathogenic fungi is a successful, sustainable alternative to chemical insecticides. Mediterranean flour moth, Ephestia kuehniella, is one of the most important insect pests infesting stored grain of cereals worldwide. This study isolated and determined some entomopathogenic fungi's efficacy in flour moth biocontrol, E. kuehniella. Materials and Methods Different strains of entomopathogenic fungi were isolated from the soils of various districts of Azarbaijan province in the Northwest of Iran. Their virulence against E. kuehniella larvae was evaluated. Isolates of various entomopathogenic fungi were isolated and purified using a soil trap from twenty distinct soil specimens. The immersion technique evaluated their pathogenicity against E. kuehniella in three replicates. This was done at 104, 105, 106, 107, and 108 conidia/mL concentrations. All selected fungal isolates were identified based on morphological features and mycological parameters. Results Four isolates of B. bassiana (BVA, BVB, BVE, and BVF) and two of L. lecanii (LCA and LC) from fourteen isolates were isolated. Six fungal species, namely Lecanicillium lecanii and Beauveria bassiana, were identified among the fourteen isolates collected. The bioassay assessment revealed that E. kuehniella fourth-instar larvae were susceptible to all isolates and that the larval death rate increased with rising conidial concentration. The BVA and BVB isolates of B. bassiana showed the maximum virulence, with nearly 2.5×105 and 2.8×105 (conidia/mL) LC50, while the BVF isolate of B. bassiana had the least virulence among the other isolates evaluated, with nearly 2.2×107 (conidia/mL) LC50 on E. kuehniella. The lowest LT50 value (3.72 days) using a 108 conidia/ml concentration on E. kuehniella larvae was shown on the BVA isolate. Discussion A comparison of the means and grouping of isolates showed a significant difference between isolates and the effectiveness of different concentrations. Also, the BVA isolate of B. bassiana had greater efficiency than the other isolates, and therefore, they will be more suitable for use in plant pest biological control programs. 

Background and objectives Cucumber crown and root rot, caused by Fusarium oxysporum f. sp. radicis cucumerinum, is one of its major destructive agents in the glasshouse planting in Iran. This disease is also known as the Fusarium damping-off. Several methods, such as chemical control and agronomic methods have been recommended so far to control this disease, but none of them has established effective control over this disease. One of the newly established strategies for the management of this disease is the biological control using endophytic bacteria, which live inside plants and can enhance plant growth by improving nutrient uptake and producing phytohormones. These bacteria can compete and control the population of other bacteria and plant pathogens within plants. This study evaluated the biocontrol capability of some selected cucumber endophytic bacteria over Fusarium crown and root disease. Materials and methods Endophytic bacteria were isolated from roots, stems, leaves, flowers, fruits, and seeds of different healthy cucumber cultivars including, Negin, Danje 98, Danje 195, Nagin and, Native Basmang. Bacterial strains were isolated from plant tissues using different culture media. In-vitro biological control assays, such as cross-culture and agar permeable metabolite assays, were performed to determine the biocontrol efficiency of endophytic bacteria against F. oxysporum f.sp. radicis cucumerinum. The bacterial strains with better results were chosen for glasshouse assay. Two isolates with significant biocontrol efficiency were selected for molecular indentification. The 16srDNA barcoding was performed using universal primers for bacterial identification. Then, the sequencing results were analyzed using MEGA-X software, and phylogenic trees were drawn using the neighbor-joining method. The selected biochemical tests confirmed the molecular results. Results and discussion A total of 140 endophytic bacterial isolates were isolated and purified from roots, stems, leaves, flowers, fruits, and seeds of some common healthy cucumber cultivars. Based on initial cross-culture, 14 isolates out of 140 isolates showed significant antagonism properties in the cross-culture and agar permeable metabolite assays, which were selected for further studies. After evaluation of the effective mechanisms, their antagonistic properties, such as the production capability of antibiotics, volatile compounds, siderophore, auxins, hydrogen cyanide, and protease enzyme, eight isolates were selected as the most potential bacterial isolates for biocontrol activity in the greenhouse. Finally, two bacterial isolates were selected for molecular identification using 16srDNA barcoding. The sequencing results indicated that the two selected isolates with 98% similarity could belong to Lysinibacillus mangiferihumi and Lyisinibaillus fusiformis species. The biochemical results confirmed the molecular results.

Lime witches' broom disease associated with ‘Candidatus Phytoplasma aurantifolia’ is one of the most serious threats to lime production in Oman, United Arab Emirates and Iranian southern provinces. In this study, under warm condition (35-37°C and 25-27°C day/night) the reaction of four genotypes of Persian lime including TLCR10, TLCRO, TLC876 (tolerant genotypes) and RA (sensitive genotype) to ‘Ca. P. aurantifolia’ was investigated via graft inoculation. Also, under cool condition (24-26°C and 18- 20°C day/night) using the same inoculation method, the reaction of RA genotype to this pathogen was evaluated. Quantitative PCR was used for detection and quantification of ‘Ca. P. aurantifolia’ in the inoculated plants. At 48 weeks post-inoculation, the copy numbers of ‘Ca. P. aurantifolia’ per 100 ng of total plant DNA in TLCRO, TLC876 and TLCR genotypes was very low (17, 10 and 12, respectively) and no disease symptoms were observed. In RA genotype under warm condition, the mean copy numbers of ‘Ca. P. aurantifolia’ per 100 ng of plant total DNA was higher than that of cool condition and showed significant differences (P < 0.01) . Furthermore, the disease symptoms were only appeared under the warm condition. The results of the present study showed that TLC10, TLC876 and TLCRO genotypes had high tolerance to ‘Ca. P. aurantifolia’ and can be introduced as tolerant or resistant cultivars to ‘Ca. P. aurantifolia’. These tolerant genotypes can be used in genetic breeding programs to produce resistant and tolerant cultivars. The results also indicated that higher temperature may change susceptibility of

Bacterial canker disease of stone fruit trees is one of the most important diseases in the world. In recent years, increasing of stone fruits canker disease symptoms as well as oozing and blast has been observed in some area in East Azerbaijan province of Iran. Fluorescent Pseudomonas syringae pv. syringae (Pss) strains were isolated from apricot trees which showed infected bud, bloom, branch and stem. The isolated strains were characterized based on their morphological, physiological and biochemical properties especially LOPAT and GATTa tests. Host preference was not observed among the tested strains and they showed pathogenicity on apricot green-cut twigs and green been pods with different disease severity. A 725-bp fragment of the syrB gene which is required for synthesis of syringomycin was amplified using specific primers in all strains. The tested strains inhibited the Geotrichum candidum mycelial growth with significant differences by toxin production. Using specific designed INAF/INAR primers, the inaZ gene was partially amplified and different range of ice nucleation activity was detected in all Pss strains. Constructing dendrograms using Bayesian inference showed genetic diversity among strains based on partial sequencing of 16S rRNA, rpoD and inaZ genes. These results showed that there are diversity among the causal agent strains of apricot canker disease based on both pathogenicity, toxin production and ice nucleation activity phenotypes and genetics.

In recent years, due to the increase in canker symptoms on almond and apricot trees suspected to Pseudomonas syringae pv. syringae (Pss) strains in East Azerbaijan province, detection and determination of some phenotypic characters and genetic characterizations of Pss strains were performed after sampling from 13 different geographical regions. A total of 14 Gram negative and fluorescent producing bacterial strains isolated from apparently diseased samples were identified as Pss based on biochemical and differential LOPAT and GATTa tests. Strains showed slight differentiation in morphological, biochemical and physiological tests. Partial sequences of the rpoD gene confirmed the results of the morphological and phenotypical tests. Pss strains had significant differences in regard to inhibition of Geotrichum candidum mycelial growth by toxin production. A 725-bp fragment of the syrB gene required for synthesisof syringomycin was amplified in all Pss strains. Based on pathogenicity tests on apricot twigs, strains were divided into two groups, one of higher and one of lower virulence. Partial sequences of the syrB gene and constructing a dendrogram using Bayesian inference showed genetic diversity among ten studied strains and divided them into two main groups.This grouping was similar to strains’ grouping based on partial sequences of the rpoD gene.