The investigation of the effect of garlic and thyme extracts on orange green mold (Penicillium digitatum), defense enzymes and genes expression

The use of chemical pesticides has caused environmental hazards as well as the creation of residues on food products. In this research, the extracts of Zataria multifloraBoiss. and Garlic (Allium sativum L.) were used for controlling the green mold of orange caused by Penicillium digitatum, invitro and invivo at 15 ̊C. In this study, the effect of plant extracts against the pathogen was evaluated using two methods, included the paper disc and mixing with culture media. Then, the effect of these extracts on the fruit was studied against the pathogen. The level of activity of the enzymes including peroxidase, catalase and polyphenol oxidase, as well as total phenol content were measured. Finally, the expression of catalase, peroxidase and polyphenol oxidase genes was evaluated using the Real time PCR method. The results of disc test showed that aqueous and alcoholic extracts of garlic had the highest effect on fungal mycelium growth with 60 mg at ml concentration and 32.20 mm and 26.12 mm diameter of inhibition zone respectively. The mixing culture test showed that aqueous and alcoholic extracts of garlic with 65.25 and 75.26 percent of the inhibitory effect on the pathogen, respectively, showed the best control compared to the control in 600 mg at L concentration. The results of invivo assays indicated that 6×1000 concentration of aqueous and alcoholic garlic and thyme extracts had the lowest of decay area with 5.3 and 3.26 cm2 respectively (for garlic) and 7.44 and 4.15 cm2 for thyme. Results of enzyme activity of peroxidase and polyphenol oxidase showed that the highest activity of both enzymes was 9 days after sampling and in the treatment of 6×1000 garlic extract. Based on the results of laboratory and storage tests, the extract of both garlic and thyme are introduced as natural constituents with controlled potentials. The genes expression levels of enzymes as peroxidase, polyphenol oxidase, and phenylalanine ammonialis had the same trend to the activity of two enzymes over a period of 12 days. Based on the results of invivo and invitro tests, the extract of garlic and thyme are introduced as natural compounds with high controlling potentials.