Protective role of plant growth-promoting fungi Aspergillus chevalieri OP593083 and Aspergillus egyptiacus OP593080 as biocontrol approach against Alternaria leaf spot disease of Vicia faba plant

Abstract

AbstractCrop loss brought on by phytopathogens is a significant issue that affects the entire world. Synthetic pesticides have been used for years to prevent economic losses caused by phytopathogens, raising severe worries about the environment and public health. Therefore, today, there is growing interest in using helpful microorganisms to control plant pathogens. In this way, Aspergillus chevalieri AGH-1 OP593083 and Aspergillus egyptiacus AGH-4 OP593080 isolated from wheat rhizosphere have been applied as plant growth-promoting fungi (PGPF) for combating early blight disease caused by Alternaria solani (A. solani) and inducing the defense system and growth promotional strategies in Vicia faba. Two milligrams per milliliter ethyl acetate crude extracts of A. chevalieri and A. egyptiacus demonstrated effective antifungal efficacy against A. solani with an inhibition zone of 18 and 16 mm respectively compared with 20 mm attained by fluconazole as a positive control. Moreover, the minimum inhibitory concentrations (MIC) were (0.25 and 0.5 mg/ml) for A. chevalieri and A. egyptiacus extracts respectively. Data showed that A. chevalieri was the best isolate producing indole acetic acid (IAA) and siderophores (+ + +) followed by A. egyptiacus (+ +). Also, the best isolates capable of phosphate solubilization in the soil was A. egyptiacus (+ + +), followed by A. chevalieri (+ +). It is interesting that the PGPF isolates used, whether single or mixed, showed a significant improvement in all growth and yield as well as photosynthetic pigments in Vicia faba. Moreover, A. chevalieri and A. egyptiacus played an important role in improving plant immunity by increasing phenol, proline, and antioxidant enzymes (POD and PPO) activities, as well as reducing oxidative stress by reducing MDA and H2O2. We can conclude that A. chevalieri and A. egyptiacus are considered eco-friendly safe strong inducers of Vicia faba plant immunity alternatives to chemical pesticides against A. solani early blight to preserve plant, soil, and human health.