SUPPRESSION OF FUSARIUMINDUCED CELLULAR DAMAGE AND DEATH IN WHEAT BY LOWDOSE Cd2+ PRETREATMENT
S. Mohapatra, B. Mittra
In the recent past, low-dose metal ion treatments have been investigated as inducers of plant resistance to biotic stress. In this work, the efficacy of 50 μM Cd2+ in diminishing wheat (Triticum aestivum) sensitivity to Fusarium oxysporum infection was assessed. In parallel, the involvement of reactive oxygen species and related scavengers in the phenomenon was investigated. The results show that wheat seedlings infected with F. oxysporum exhibit a higher disease severity index as compared to co-stressed seedlings (Cd2+ pre-treatment followed by Fusarium inoculation). An enhanced level of
superoxide anion (O2· ) was observed in Fusarium-infected tissues when compared
with co-stressed tissues. Fusarium-infected tissues showed susceptibility for cell damage and death possibly due to generation of malondialdehyde as a result of lipid peroxidation, as compared to co-stressed tissues. Accumulation of total phenolics was observed to be enhanced in co-stressed tissues compared to Fusarium-infected tissues, as was the activity of antioxidant enzymes such as catalase, guaiacol peroxidase and polyphenol oxidase. Interestingly, superoxide dismutase activity was observed to be higher in Fusarium-infected tissues when compared with co-stressed tissues, possibly as
an indirect consequence of enhanced O2· accumulation. Thus, low-dose Cd2+ increases
resistance or tolerance in wheat seedlings possibly by enhancing the activity of antioxidant enzymes, which in turn might help to minimize Fusarium-induced oxidative damage and death.