Format: ORAL

Akitoshi Iwamoto1, Yuna Yoshioka2, Ryoka Nakamura1, Takeshi Yajima1, Wakana Inoue1, Kaho Nagakura1

1 Department of Biological Sciences, Faculty of Science, Kanagawa University 2 Department of Biology, Tokyo Gakugei University

The mechanical forces have a key role in plant development, including the floral development in angiosperms. Our observation revealed that the phyllotactic variation in the staminate flower of Ceratophyllum demersum should be caused by the mechanical forces on the adaxial side of floral primordia, which may be a common mechanism in angiosperms. Based on this result, we have developed a novel experimental system for the analysis of the effects of mechanical forces on the floral meristem of Arabidopsis thaliana, aiming to induce morphological changes in flowers. A micromanipulator with a microdevice which isshapedtofitthe contourof the abaxial side of young floral primordium is used to cause the contact pressure on floral primordia in this experimental system. We conducted contact experiments using this system, and successfully induced morphological changes in floral primordia during development. In several primordia, the tip of the abaxial sepal was divided into two or three lobes through their development. Another pressured floral primordium developed an additional sepal on the abaxial side (two abaxial sepals). On the other hand, we also found the fusion of sepals in some floral primordia. These results suggest that the mechanical forces have multiple effects on the floral development.