Physiological and biochemical alterations on maize leaves infected by Stenocarpella macrospora

Abstract

This study aimed to analyze the antioxidant system responses and photosynthetic performance of maize cultivars (ECVSCS155 and HIB 32R48H) infected by Stenocarpella macrospora. The activities of some antioxidant enzymes and metabolites and the concentration of reactive oxygen species in maize leaves as well as chlorophyll a fluorescence imaging parameters were assessed. For both cultivars, the enzymatic and non-enzymatic components of the antioxidant system were dramatically altered in the infected leaves. As the disease symptoms became more noticeable, enzyme activities (e.g., peroxidases and catalases) and the concentration of ascorbate and glutathione decreased accordingly. The concentrations of hydrogen peroxide and malondialdehyde equivalents increased, thereby contributing to the intensification of lipid peroxidation upon damage to cell membranes caused by fungal infection. Decreases in maximum fluorescence, maximum PSII quantum efficiency, effective PSII quantum yield and quantum yield of regulated energy dissipation coupled with increases in initial fluorescence and quantum yield of non-regulated energy dissipation were directly related to the progressive loss of photosynthetic activity coupled with the development of oxidative stress during the S. macrospora infection process.