Comparative structural and biochemical study on calcium effects on Cercospora leaf spot disease on sugar beet

This study was designed to investigate the effect of calcium chloride and calcium chelate on the interaction between sugarbeet plants and Cercospora leaf spot (CLS) disease as well as its direct effect on the pathogen using scanning electron microscope. It was clearly observed that, both calcium salts significantly reduced CLS disease severity with calcium chelate being more effective in CLS disease control. The levels of chitinase, β1,3 glucanase and Polyphenol oxidase (PPO) of the salttreated plants were significantly increased as compared to the untreated control. Thus, both calcium chelate and chloride have a role in triggering the induction of plant resistant. The increase of chitinase, β1,3 glucanase and PPO was correlated with the reduction in disease severity. Scanning electron microscopy showed that, calcium treatments decreased the density of emerging conidiospores compared to those of untreated infected control. The stomatal guard cells of the calcium-treated leaves appeared closure than in the untreated control. This study concludes that, the two tested calcium salts have a role in inducing disease resistance as well as stomatal functioning. They may also have a fungistatic effect on the pathogen.