Abstract
Silene latifolia is a dioecious plant that has X and Y sex chromosomes. When the female plant is infected with smut fungus, its female flower elongates the stamens to be a suspected hermaphrodite flower. We isolated S. latifolia homologs (SlLFY, SlWUS, SlUFO etc.) of floral homeotic genes, and examined their temporal and spatial expression-patterns in the male, the female, and the infected female by using in situ hybridization. One of them, SlUFO was expressed in whorls 2 and 3 regardless of sex at the stage 2 when the stamen and carpel were not differentiated. The number of surface cells in the whorl 4 where SlUFO expression was not observed is 23 in the male flower, but 42 in both female and infected female flowers. The whorl 4 in the infected female flower is the same size of that of the female flower and bigger than that of the male flower.
