جستجوی مقالات مرتبط با کلیدواژه « فوزاریوم » در نشریات گروه « زیست شناسی »

Complex disease caused by the root-knot nematode, Meloidogyne javanica, and the fungus, Fusarium oxysporum f. sp. radicis-cucumerinum, has limited cucumber cultivation in Iran. Therefore, access to the nematode-resistant cultivars has a crucial role in disease control. The Assessment of plant defense compounds in the Complex disease helps understand the molecular mechanisms of resistance and the production of nematode-resistant cultivars. After inoculation of the plants in a greenhouse, the peroxidase enzyme and the phenolic compounds were measured using spectrophotometric method. The experiment was conducted based on a factorial completely randomized designed with 14 treatments, including control, fungi alone, nematode alone in four inoculations level viz. 1500, 3000, 4500, and 6000 J2s, fungus + nematode simultaneously, and fungus a week after nematode inoculation with 4 replications. Phenolic compounds increased by %54.74 and %92.34 and peroxidase enzyme activity increased by %50.64 and %63.31 in plants inoculated with fungus alone and nematode alone (6000 larvae) compared to the control, showing that these substances act as defensive compounds in cucumber. Results showed that increasing the nematode population in inoculated plants improved the defense compounds levels.  Inoculation of nematode (6000 larvae) followed by fungus led to %80 and %54.48 increases in phenolic compounds and peroxidase activity, respectively as compared with the control which might be attributed to the synergistic effects of pathogens. The fungi had a more active role than nematodes in increasing the peroxidase compared to the phenolic compounds, which indicated the complex nature of nematode parasitism in the nematode-plant interaction. Decrease in the defense compounds in Negin cultivar (susceptible to Fusarium) and increase in the level of these compounds in Khasib (tolerant to Fusarium) and Dastjerdi (tolerant to nematode) cultivars showed that the production of the defensive compounds may be related to the cucumber resistance to pathogens.

Dry rot is one of the most important diseases of potato in storages. The aim of this study was to determine dry rot severity in potato storages of Ardabil, identify the disease causal agents and evaluate some potato cultivars resistance to the disease.
Totally 150 infected samples were collected from thirty nine studied storages in Ardabil. Dry rot severity and the prevalence of infected tubers were determined by surveying three 50 kg bags of potato in the storages. Fungi isolated and purified from the tubers with dry rot symptoms. A factorial design with four replications was applied in order to evaluate the reaction of five potato cultivars to four Fusarium species and determining the resistant one to dry rot. Potato tuber slices were inoculated by conidial suspension of Fusarium species. Four days after inoculation and maintaining in darkness and 25oC, the cultivars susceptibility was identified.
Four species of Fusarium were identified as dry rot causal agents in Ardabil as follows: F. oxysporum, F. poae, F. solani and F. sporotrichioides. There was no significant difference between Fusarium species in pathogenicity. The reaction of cultivars to various Fusarium species was different. Boren had the lowest infection (12.5%) and Sabalan showed the highest (98.87 %). Sabalan ،Khavaran ،Agria and hybrid line 3970093 displayed the highest susceptibility to various studied Fusarium species.
Discussion and Based on the results, Boren is introduced as the most resistant cultivar to Fusarium dry rot and Sabalan, Agria and hybrid line 3970093 as the susceptible ones.

Fusarium sp. is one of the most important agents that infect the root and crown of canola in worldwide. The aim this survey was to identify Fusarium species associated with crown and root of canola grown in Khuzestan province and pathogenicity of dominant species in this area. Following isolation and purification of the samples, specific media were used to identify the isolates. The isolates were used for infection of the trees in an accidental manner. In this study, a total of 73 isolates of Fusarium were isolated. F. solani, with 23 isolates was the most dominant fungi in these samples while F. oxysporum and F. verticillioides showed the lowest number of isolates. In this study, F. nigamai, F. verticillioides and F. clamidosporas were isolated for first time from crown trees grown in Iran. The pathogenesis tests showed that F. solani and F. equiseti showed the highest pathogenesis. Based on the severe infection in the roots in these samples, it is recommended to investigate the volume of damages and appropriate strategies for control of pathogenesis of Fusarium in farms.