Ground-based microgravity simulators for plant research: principles and biological responses

Gravity is a fundamental environmental factor influencing plant evolution and development. As humanity prepares for long-duration space missions, understanding plant responses to microgravity is crucial for sustainable space agriculture. While the International Space Station (ISS) offers an ideal research environment, high costs and limited accessibility have necessitated the use of ground-based microgravity simulators, such as 2D and 3D clinostats and Random Positioning Machines (RPM). This review summarizes the physical principles of these devices and synthesizes plant biological responses, including organ-level morphogenesis, cellular structure, hormonal balance, and molecular metabolism. We critically compare ground-based simulation data with actual spaceflight results, identifying areas of high reproducibility-such as statolith randomization and automorphogenesis-as well as significant discrepancies that might be caused by simulator-specific artifacts like mechanical vibration, centrifugal acceleration, and fluid shear stress. Furthermore, we emphasize the need for standardized performance metrics, including time-averaged simulated microgravity (taSMG) and the degree of gravity dispersion (DGD), to enhance data reliability. Finally, we discuss how technical innovations such as brushless direct current (BLDC) motor integration and 3D printing can bridge the "space-ground gap". This review provides a strategic framework for optimizing ground-based research to support the development of life support systems for future lunar and Martian habitats.