微重力环境影响拟南芥生长发育的研究

Based on the flight experiment of "SJ-10" recoverable satellite and follow-up studies, we will focus on the mechanism of plant cell wall adaptation to microgravity. At the levels of whole-genome DNA methylation and transcriptome researches, the key genes in microgravity stimulation signaling pathways, regulation of cell wall metabolism and metabolism of cell wall composition will be identified through data joint analysis and mining. The function of these genes will be evaluated by using loss-of-function mutants and over-expression Arabidopsis in order to understand their role in plant adaptation to microgravity conditions. The transgenerational memories of plant microgravity effects were determined by analyzing the phenotype of Arabidopsis which returned to the ground alive. Their molecular mechanism of epigenetic modification will be explained. These researches will help us to understand the mechanism of the effects of microgravity on plant growth and development and provide theoretical basis for future space plant cultivation.

本课题在“SJ-10”返回式卫星飞行实验和后续研究的基础上，围绕研究植物支撑系统——植物细胞壁适应微重力环境的机制，在全基因组DNA甲基化和转录组水平上，联合分析挖掘与微重力刺激信号转导通路、调控植物细胞壁代谢、细胞壁组成成分代谢相关的关键基因。用它们的功能缺失突变体和过表达转基因植物分析验证它们在植物适应微重力环境中的作用。通过分析活体返回地面拟南芥后代的表型，确定微重力效应的隔代记忆现象。进一步从表观遗传修饰的角度探讨这种表观遗传记忆背后的分子基础。综合上述研究，进一步认识微重力环境影响植物生长发育的机理。为未来空间植物栽培奠定理论基础。

在轨道上飞行60小时后，拟南芥基因组的甲基化水平较低。利用“实践十号”返回式卫星在微重力环境下生长11天并返回地球的幼苗后代，系统研究了太空飞行对后代DNA甲基化、转录组和表型的潜在影响。第一代子代(F1)的全基因组甲基化分析表明，虽然在亲本中甲基化水平没有显著差异，但仍存在一些DNA甲基化差异的残留印迹。DNA甲基化和RNA测序结合分析表明，子一代中ABA激素信号通路、蛋白磷酸化、硝酸盐信号通路等多种通路表达发生改变。由于F2代仍存在一些表型差异，提示这些表观DNA甲基化修饰被部分保留，导致后代表型差异。此外，一些太空飞行诱导的遗传差异甲基化区域(DMRs)被保留。太空飞行引起的表观遗传修饰的变化影响了未来两代种子的生长。其中两个与空间飞行相关的DNA甲基化水平降低的DMRs被证实位于硝酸盐信号基因TGA1和TGA4内部，这可能与后代氮吸收和根长生长改变有关。本研究有助于更好地理解植物对逆境的适应机制，特别是对外太空环境的适应。