Composition Analysis of ‘Halo’ Area of Barley Leaf Epidermis Induced by Powdery Mildew Infection

Abstract

The halo area on the barley leaf epidermis induced by powdery mildew infection was examined using a cotton blue stain and an electron probe microanalyzer. The halo consisted of the faintly stained zones and the densely stained zones which alternately encircled the penetration point, when stained with cotton blue. With the scanning electron microscope, two slightly raised zones, the central and the outer ring zones, were clearly distinguished in the halo. They corresponded to the zones stained faintly with cotton blue. The composition analysis by the X-ray microanalyzer indicated that calcium accumulated around the penetration point and manganese and silicon in the central and the outer ring zones.