Abstract
Silene latifolia is a dioecious plant that has X and Y chromosomes. Female plants (XX) initiate development of stamens by infection of the dimorphic smut fungus Microbotryum violaceum. Until stage 7, no floral modification is observed between healthy and infected females. At stage 8, the healthy female does not develop stamens, whereas the infected female initiates to develop stamens. Expression of the floral-B function gene, SLM2, an ortholog of PISTILLATA in Arabidopsis, was examined by in situ hybridization. Until stage 7, SLM2 was expressed on whorl 2 and 3 of the healthy and infected females. At stage 8, SLM2 transcript was supressed in the stamen primordia of the healthy females. However, developing stamen of the infected female expressed SLM2 as intense as developing petals. The suppression of SLM2 expression would be removed by the smut-infection independent of the presence of Y chromosome.
