Methyl Jasmonate Modulates Peroxidase Activity in Sunflower Varieties Affected by Pathogenic Fungi

Abstract

Methyl jasmonate (Meja) is a volatile phythormone that contributes many plant critical processes, especially under biotic and abiotic stresses. Thus, Meja found to effectively regulating the biosynthesis of other plant hormones and/or enzymes, like preoxidase (POD). However, Meja specifically affects the plant antioxidant defense system, particularly POD activity are still an area of ongoing research. The current results pointed to a clear effect of the applied Meja concentration in shaping the entire response to the biotic oxidative stress resulted from the three pathogenic fungi Fusarium solani. and Macrophomina phaseolina. The higher concentration of Meja had a greater effect on both gene expression and POD enzymatic activity, which indicates the Meja importance in stimulating the defense system of sunflower varieties through which sunflower plants deal with the excessive production of reactive oxygen species (ROS) in response to the pathogenic infection. The different varieties showed different ability to cope with biotic stress represented by the three used pathogenic fungi, especially the antioxidants enzymatic activity. Sakha variety proved to have the most effective POD enzymatic activity compared to the other two Ishaqi and Aqmar sunflower varieties. Meja concentrations in its maximum level (3 μM), was more effective in stimulating the antioxidant activity in term of enzymatic activity of POD. Notably, R. solani had a greater effect on the antioxidant defense system, as it resulted in higher levels of POD enzymatic activity in the three sunflower varieties. Further investigation maybe required to better understand the Meja ability to promote the plant antioxidant system, thus the possible protective mechanisms against plant pathogens.