Processes in the infection of barley leaves by rhynchosporium secalis

Abstract

Conidia of R. secalis (Oud.) Davis germinated on barley leaves to produoe, short germ tubes and appressoria. Hyphae below the appressoria penetrated the outicle and formed extensive myoelial mats between the cuticle and the outer epidermal cell walls. Epidermal cell walls beneath the subcuticular hyphae became swollen, lamellate, and collapsed so that the inner and outer walls of the epidermis came together. Penetration of the cuticle, and collapse of the epidermal cell walls and mesophyll cells, appeared to be due to the activity of materials excreted by the fungus. Subcuticular stromata formed below inoculated surfaces. Hyphae grew from these areas, through the mesophyll, to the opposite side of the leaf where they formed stromata in substomatal cavities. Conidia, which were formed on both types of stromata, protruded through the cuticle above subcuticular stromata and were extruded through stomatal pores from Bubstomatal stromata. © 1970 CSIRO.