Gravitational and hormonal control in secondary xylem formation of Japanese flowering cherry.

It has been reported that Japanese flowering cherry promotes the formation of tension wood in the upper side of the inclined stem, which induces the negative gravitropism. In the other hand, the plant under simulated micro-gravity conditions reduces the width of the secondary xylem and increases the density of the vessels, which means decreased the density of the fiber cells. The plant under simulated micro-gravity conditions showed that the inhibition of xylem development and the decreased supporting mechanism in the stem. In this study we examined that the effects of auxin and gibberellin in the plant under simulated micro-gravity conditions and inclined stimulus. The gibberellin treatment promotes the secondary xylem development under simulated microgravity conditions and inclined stimulus. The upper side of the inclined stem contents much higher levels of IAA and gibberellin A1(GA1) than the lower side of that.