The Spectrum of Infections by Fusarium Species on Codiaeum Variegatum (L.) Blume Cultivars as Influenced by Fructose Specific Lectin

This study sought to have an insight into the mechanism of action of diseases responsible for the susceptible Codiaeum variegatum (garden croton) leaves induced by Fusarium species and the clinical importance of the disease resistant types. The plants were obtained from the Babcock University Germplasm Repository. Therefore, phytopathogenic Fusarium species were isolated from three diseased susceptible cultivars of C. variegatum (ovalifolium, royal-like and punctatum). Accordingly, lectin was isolated, purified and characterized from the leaves of a resistant garden croton cultivar (royal), and further evaluated for antifungal activity using isolates of Fusarium lateritium and F. semitectum obtained from the three diseased cultivars. The heamagglutinating activity of the purified lectin was non selective to type of blood group (A, B, AB and O) and was inhibited by fructose, sialic acid, and copper sulphate, but was enhanced by galactose, calcium chloride, sodium chloride and magnesium chloride. Optimum heamagglutinating activity of the lectin was achieved at 30–40℃ and pH 5.0–6.0. The lectin exhibited antifungal activity against the two Fusarium species in a non-concentration dependent manner. It is therefore concluded that Fusarium species are major phytopathogens of the garden croton plant and their spectrum of pathogenicity is dependent on the presence or absence of lectins. In addition, the resistant cultivar of C. variegatum (cv. royal) used in this study may be a suitable candidate for the prevention and treatment of fungal infections.