Agronomy Department, Faculty of Agriculture, Zagazig University, Zagazig, Egypt.
Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, 28040, Madrid, Spain.
Sci Rep. 2018 Apr 23;8(1):6424. doi: 10.1038/s41598-018-24942-7.
Gravity is the only component of Earth environment that remained constant throughout the entire process of biological evolution. However, it is still unclear how gravity affects plant growth and development. In this study, an in vitro cell culture of Arabidopsis thaliana was exposed to different altered gravity conditions, namely simulated reduced gravity (simulated microgravity, simulated Mars gravity) and hypergravity (2g), to study changes in cell proliferation, cell growth, and epigenetics. The effects after 3, 14, and 24-hours of exposure were evaluated. The most relevant alterations were found in the 24-hour treatment, being more significant for simulated reduced gravity than hypergravity. Cell proliferation and growth were uncoupled under simulated reduced gravity, similarly, as found in meristematic cells from seedlings grown in real or simulated microgravity. The distribution of cell cycle phases was changed, as well as the levels and gene transcription of the tested cell cycle regulators. Ribosome biogenesis was decreased, according to levels and gene transcription of nucleolar proteins and the number of inactive nucleoli. Furthermore, we found alterations in the epigenetic modifications of chromatin. These results show that altered gravity effects include a serious disturbance of cell proliferation and growth, which are cellular functions essential for normal plant development.
重力是地球环境中唯一在整个生物进化过程中保持不变的因素。然而，目前尚不清楚重力如何影响植物的生长和发育。在这项研究中，拟南芥的体外细胞培养物暴露于不同的改变重力条件下，即模拟微重力（模拟火星重力）和超重（2g），以研究细胞增殖、细胞生长和表观遗传学的变化。评估了暴露 3、14 和 24 小时后的效果。在 24 小时的处理中发现了最相关的变化，模拟微重力的变化比超重更为显著。在模拟微重力下，细胞增殖和生长解偶联，类似于在真正或模拟微重力下生长的幼苗分生组织细胞中发现的情况。细胞周期各阶段的分布发生改变，以及所测试的细胞周期调节剂的水平和基因转录。核糖体生物发生减少，根据核仁蛋白的水平和基因转录以及失活核仁的数量。此外，我们发现染色质的表观遗传修饰发生了改变。这些结果表明，改变重力的影响包括细胞增殖和生长的严重干扰，这是正常植物发育所必需的细胞功能。
