Gravity is a key determinant in orienting plant stems for proper growth and development. An intact and dynamic actin cytoskeleton is thought to be important for plants to respond to gravity; however, pharmaceutical treatment and mutant analyses have yielded conflicting results. In Arabidopsis (Arabdopsis thaliana) shoots, for example, pharmacological disruption of the F-actin cytoskeleton formation by Latrunculin B (LatB) led to increased gravitropic response. However, other studies have questioned the need for an intact F-actin network for graviperception in inflorescence stems, and Lat-B treatment caused reduced amyloplast mobility in Arabidopsis endodermal cells. Previously, it has been shown that the actin cytoskeleton in rice (Oryza sativa) is controlled by Rice Morphology Determinant (RMD), a type-II formin protein specifying rice morphology by regulating actin nucleation and organization. RMD also regulates actin dynamics and auxin homeostasis during root cell elongation and growth, as well as pollen tube development, and it is required for crown root angle in response to P starvation. In the present contribution, Song et al. (10.1104/pp.19.00497) show that RMD promotes shoot negative gravitropism by regulating actin organization and amyloplast sedimentation in the endodermis of light-grown shoots. Light-grown rmd mutant shoots exhibited agravitropic phenotypes. In contrast, etiolated rmd shoots displayed normal negative shoot gravitropism. The authors report that RMD maintains an actin configuration that promotes statolith mobility in gravisensing endodermal cells, and which ensures proper auxin distribution in light-grown, but not dark-grown, shoots. RMD gene expression is diurnally controlled and directly repressed by the phytochrome-interacting factor-like protein OsPIL16. Overexpression of OsPIL16 led to gravisensing and actin patterning defects similar to the rmd mutant. These findings provide insights into the mechanisms by which RMD is involved in controlling shoot negative gravitropism in a light-dependent manner.