Weeraddana, Chaminda De Silva2012-08-152012-08-152012-08-15http://hdl.handle.net/10222/15239An alkaline extract of the brown seaweed, Ascophyllum nodosum (ANE) increases plant growth and imparts resistance against biotic stresses. However, little is known of the effects of ANE on insects. Myzus persicae, green peach aphid (GPA), and Arabidopsis model were used to determine whether application of ANE confers protection from GPA infestation. GPA colonization increased in ANE treated plants, associated with improved biomass. However, ANE treated plants exhibited less cell death and also showed a greater ability to recover from GPA injury. Lower expression of SAG13, SAG21 and CHL1 and a higher expression of ARR5 was observed in ANE treated plants. Taken together, gene expression along with lower cell death suggests ANE may delay senescence in Arabidopsis. Delayed senescence in Arabidopsis following ANE treatment may be a result of increased cytokinin activity. Increased GPA numbers could be, at least in part, due to delayed senescence in Arabidopsis following ANE treatment.enBROWN SEAWEEDASCOPHYLLUM NODOSUMARABIDOPSIS THALIANAMYZUS PERSICAEThesis