Tracing Gravity: Time-Lapse & Growth Kinematics of Starchless Marchantia Mutants 🌿🌀🔬
- PlantHouse Enterprise
- 6 days ago
- 2 min read
Published on: 19 August 2025
This scientific time-lapse movie provides a side-by-side comparison of the gravitropic responses in the liverwort Marchantia polymorpha. By tracking the growth of "narrow structures" in the dark, the video reveals how the presence or absence of starch-filled amyloplasts dictates the plant's ability to navigate gravity.
Gravitropism is a plant response to gravity that directs organ growth and development, playing a key role in the adaptation of land plants. While its molecular basis has been extensively studied in flowering plants, much less is known about this process in other plant lineages. Here, we investigated the gravitropic response of the liverwort Marchantia polymorpha, a model for early land plant evolution. In darkness, the thallus tips extended upward, forming several straight, narrow structures whose growth direction was consistently opposite to gravity and disrupted by clinostat treatment. These structures contained amyloplasts in parenchymatous cells, and their sedimentation preceded gravitropic curvature, suggesting a role as statoliths. Amyloplast sedimentation started near the tip and slowed with distance, and in more distal regions, both the size and the number of amyloplasts decreased. In starchless mutants (Mppgm1 and Mpaps1), the narrow structures displayed abnormal growth directions, although they still tended to elongate upward. These results indicate that while amyloplasts are required for proper gravitropism, M. polymorpha retains the ability to sense gravity even without well-developed amyloplasts. Our findings suggest that land plants use amyloplasts as statoliths but also possess amyloplast-independent mechanisms for gravitropic sensing.
Keywords: Amyloplast, gravitropism, Marchantia polymorpha, starch, statolith, thallus
Citation:
Mimi Hashimoto-Sugimoto, Takuya Norizuki, Shoji Segami, Yusaku Ohta, Noriyuki Suetsugu, Takashi Ueda, Miyo Terao Morita, Amyloplasts are necessary for full gravitropism in thallus of Marchantia polymorpha, Journal of Experimental Botany, Volume 76, Issue 22, 4 December 2025, Pages 6741–6757, https://doi.org/10.1093/jxb/eraf375
Attribution 4.0 International — CC BY 4.0 - Creative Commons
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