Characterization of the role of a cycloartenol synthase gene (ZMCAS494) in Zea mays responses to drought stress
Plant Sterols are an important part of the membrane and their role is to control cell membrane fluidity and permeability. Several studies have indicated that plants that are mutant for genes that play a role in the sterol biosynthetic pathway show increased sensitivity to drought stress. Even though the exact molecular mechanism is unknown, such studies suggest that sterols do play a role in plant drought stress responses. To elucidate the mechanism through which sterols regulate Zea mays responses to water deficit, the effect of drought stress on phytosterol content and on expression of a cycloartenol synthase-like gene (ZMCAS494) was investigated. The effect of inhibition of sterol biosynthesis, using terbinafine, on maize reactive oxygen species production and on activity of the superoxide dismutase, ascorbate peroxidase and glutathione peroxidase enzymes was also investigated. Quantitative polymerase chain reaction (qPCR) analysis of the expression of ZMCAS494 indicated a change in gene expression in response to drought. Inhibition of phytosterols synthesis resulted in altered ascorbate peroxidase activity, glutathione peroxidase activity as well as superoxide dismutase activity in roots and leaves of maize. The ROS content of maize leaves was increased by inhibition of phytosterols synthesis. Data obtained in this study suggests a relationship between sterol biosynthesis, sterol content and reactive oxygen species signalling.