Lipid Peroxidation and Antioxidant Activities Involved in Resistance Response against Downy Mildew in Opium Poppy
2010
Dubey, Mukesh K. | Shasany, Ajit K. | Dhawan, Om P. | Shukla, Ashutosh K. | Khanuja, Suman P.S.
The aim of this study was to observe the lipid peroxidation (LP) of cell membranes and antioxidant systems in response to inoculation of Peronospora arborescens causing downy mildew (DM) in opium poppy. Contents of the LP product, malondialdehyde (MDA) and antioxidant glutathione (GSH) were determined in leaves of two opium poppy genotypes, Pps-1 (highly resistant to DM) and Jawahar-16 (highly susceptible to DM) at different time intervals after inoculation (12 h, 24 h, 48 h and 72 h). The provided GSH content corresponded to that of total non-protein sulfhydryl groups. In leaves of Jawahar-16, a significant decrease in concentration of GSH and a persistent increase in concentration of MDA were recorded after inoculation in comparison to leaves of control plants. The continuous decrease in GSH content contributed to damage of cell membranes leading to disease development in Jawahar-16. On the other hand in a resistant genotype (Pps-1), initially at 12 h after inoculation (hai) the level of GSH was found to be high, but a transient and highly significant decrease in content of GSH and increase in content of MDA was observed at 24 hai in comparison to control plants of same genotype and also in comparison to inoculated plants of susceptible genotype (Jawahar-16). These results indicate that generation of GSH and MDA is negatively correlated during the infection process as found in the case of DM-resistant genotype Pps-1 at 24hai, which also suggests an increased need by the host plant for oxidative stress, required for hypersensitive response mediated defense mechanism.
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