Morphological analysis on developmental stages of smut-induced anthers in female flowers of the dioecious plant, Silene latifolia

Abstract

The dioecious Silene latifolia has X and Y sex chromosomes. S. latifolia infected with a dimorphic smut fungus Microbotryum violaceum develops anthers filled with smut spores instead of pollen. We investigated the morphological modifications provided by the infection to host plants using a natural SEM, and the relationship between the changes of the interior of floral primordia and the localization of smut hyphae by the observation of Technovit-sections. Smut hyphae were observed everywhere in early floral primordia. Anthers in females initiated sporogenous cell formation but lacked any parietal cell layers that differentiated into endothecium, middle cell layers and tapetal tissue in infected females as in males. Smut spore formation was initiated in the intercellular regions of the sporogenous cells, involving the degeneration of premature sporogenous cells and tapetal tissues. The development of epidermis, endothecium and middle cell layers were morphologically normal.