Cyclo(<scp>l</scp>-proline-<scp>l</scp>-serine) Dipeptide Suppresses Seed Borne Fungal Pathogens of Rice: Altered Cellular Membrane Integrity of Fungal Hyphae and Seed Quality Benefits
Baninderjit Kaur Poonia, A. S. Sidhu, Anju Sharma
Abstract
Five proline-containing diketopiperazines (Pro-DKPs) produced by antagonistic microorganisms as secondary metabolites were selected and synthesized under laboratory conditions. Out of five synthesized Pro-DKPs, cyclo(l-Pro-l-Ser) (DKP-6) revealed the best inhibition of fungal pathogens (Fusarium verticillioides and Fusarium fujikuroi) of rice under in vitro conditions with effective doses lower than standard fungicide carbendazim. DKP-6 induced stress on the fungal cell membrane integrity, which was revealed by calcofluor white and propidium iodide assays, endorsed by ultra-microscopic details and soluble protein leakage assays. In vivo seed treatment of infested rice seeds with DKP-6 at 2000 μg/mL for 10 h of seed treatment inflicted best reduction in seed rot and seedling blight with respect to control and carbendazim. Significant enhancement in seedling quality parameters were also observed. The work presented the strong influence of cyclo(l-Pro-l-Ser) as a mycocidal seed treatment agent better than synthetic toxic fungicides for rice.