Metalaxyl Induced Changes in Protein Metabolism During Germination of Maize

Abstract

The present work was carried out to investigate the effect of a systemic fungicide metalaxyl as a seed treatment on the protein metabolism of maize during early germination. The study was carried out for 7 days after soaking the seeds in different concentrations of metalaxyl and a control was maintained. Biochemical analyses of whole seedlings were done up to 7 days. Changes in the amount of total soluble protein, total free amino acids, and the activity of protease were performed using standard methods. The results indicate that protein content was maximum on 4th and 6th day of germination in both control and treated seeds. Metalaxyl treatment resulted in decreased protein content (20-50% inhibition) over the untreated in a dose dependent manner till the 4th day of germination. But as the growth proceeded a proportionate increase in the protein content was observed on the 6th day of germination in fungicide treated seeds compared to the control. The specific activity of protease was decreased by 46%, 81%, 88%, 97% and 100% with 1.5mg, 3mg, 4.5mg, 6mg and 7mg concentration of metalaxyl on 3rd day of germination when compared to the control. An increase in the total free amino acids occurred during the germination and maximum free amino acids content was observed on the 5th day. Metalaxyl treatment resulted in a dose dependent depletion of free amino acids. A significant increase in proline content was found to occur in treated seeds. From the overall findings, the present study gives an insight into a protective effect of the system with an increased production of proline and decreased protease activity and free amino acids and at the same time a higher protein content during later stages of germination for a particular concentration may be due to the synthesis of novel proteins as a defense mechanism indicating the dual role of metalaxyl.