Endophytic Fungi as Potential Biocontrol Agents against Sclerotium rolfsii Sacc.-The Causal Agent of Peanut White Stem Rot Disease.

Peanut stem white rot caused by Sclerotium rolfsii Sacc. is a soil-borne disease that is widely prevailing across peanut farms, leading to serious economic losses. Screening for biocontrol agents against this pathogen is urgent. In this research, 166 fungal isolates including 136 isolates of S. rolfsii and 30 isolates of antagonistic endophytic fungi were obtained from a total of 220 samples collected from peanut farms in Guilan province, Iran. After morphological and molecular identification, six superior endophytic isolates were finally selected for the in vitro and greenhouse trials, including four isolates from Trichoderma viride, Trichoderma virens, Penicillium decaturense, and Aspergillus flavus and two isolates from Penicillium rubens. Four methods of biocontrol were used during the in vitro phase, i.e., dual culture, volatile metabolites assay, non-volatile metabolites assay (culture extract), and slide culture. It was found that T. virens had the highest capability of suppressing the mycelial growth of S. rolfsii in the dual culture method (90.98%). As for the volatile metabolites assay, the most effective isolates in inhibiting the pathogen's mycelial growth were P. rubens (MN395854.1) and A. flavus (84.30% and 73.50% inhibition, respectively). In the non-volatile metabolites method, the isolates that performed the best in suppressing the mycelial growth of S. rolfsii were T. viride and P. rubens (MN395854.1) with 91.80% and 90.20% inhibitory effects, respectively. On the other hand, in the slide culture method, all isolates, except for T. virens and T. viride, successfully controlled the development of S. rolfsii hyphae. The greenhouse trials also supported the effectiveness of endophytic fungi in controlling the pathogen on the host plants. According to the results, T. viride, A. flavus, and P. rubens (MN395854.1) were 44%, 42%, and 38% effective in alleviating the disease incidence and severity. Moreover, the application of these antagonistic fungi in the greenhouse conditions increased the height, fresh weight, and dry weight of the Arachis hypogaea plants infected with the disease causal agent compared to the plants treated only with the pathogen. The results of the in vitro and greenhouse experiments revealed that the endophytic fungi occurring in the natural microbiota of peanut are capable of bio-controlling S. rolfsii, the causal agent of peanut stem white rot disease. These findings shed new insights into the possible resistance induction in A. hypogaea plants through biological protection.

Risk assessment in academic laboratories in the west of Iran: compare the CHRA and the RSLs methods.

In the laboratories staffs, there is potential for adverse health effects in exposure to chemicals. Therefore, risk assessment is one of the main issues to prevent these effects. The purpose of this study was to assess the health risk of laboratory staffs and compare the two methods, including 'Chemical Health Risk Assessment' (CHRA) and 'Regional Screening Levels' (RSLs), that developed by the Department of Occupational Safety and Health of Malaysia and the Environmental Protection Agency respectively. Using these two methods, the places with the highest risk were identified. Comparisons showed that RSLs is a precise method without personal judgment. The CHRA is a simple method for wider chemicals that categorize risk. But CHRA includes fewer parameters compared to RSLs, as well as personal judgment. The results of the present study showed that two methods did not compatible. According to the characteristics of these two methods, it is recommended to use them as a compliment each other to obtain accurate results.