光周期途径是植物适应地球环境得以生存与繁殖不可缺少的反应机制。近年来该领域的突破性进展，使得部分重要经济植物的生长不受季节和地理位置的限制，取得了巨大的经济效益。光周期反应是建立以植物为基础的空间生命生态保障系统必须了解的关键生物学理论之一，但是，目前关于植物光周期反应的知识都是在地球重力环境下获得的。当植物进入空间微重力环境中是否仍然遵循地球重力条件下形成的光周期反应规律仍然不清楚。“实践十号”和“天宫二号”空间实验结果表明微重力对植物的光周期反应有明显的影响，但是，其作用的分子机理尚需进一步研究。本申请项目拟利用“实践十号”返回的拟南芥和水稻空间及其地面对照样品，利用基因表达谱芯片和RNA测序等手段，从转录组水平来解析微重力与光周期反应途径在植物开花调控网络中的共通点和特异性，全面系统地认识微重力在光周期调控植物开花中的作用，为揭示微重力影响光周期反应的分子机理提供直接证据。

Photoperiod pathway is an essential response mechanism, in which plants adapt to seasonal change and alternation of day and night on earth in order to survive and proliferation. Recently, breakthrough progress in this field has made the growth of some important economic crops free from seasonal and geographical restrictions and achieved great economic benefit. However, many important economic plants still cannot be carried out large-scale production under manual control, because the molecular mechanism of flowering control is unclear. Our knowledge on photoperiod pathway all obtained under the terrestrial environment. Whether the response of plants to photoperiod formed on ground can work in the same way under microgravity remains to be studied. In our pervious space experiments on board SJ-10 recoverable satellite and TG-2 space lab, we have studied the photoperiod response of Arabidopsis thaliana and rice in microgravity. Our results indicated apparent changes on photoperiod responses of plants under microgravity, such as delayed in flowering and slowed down growth rhythm, but molecular mechanism of microgravity on plants is still unknown. Here, we are plan to use the samples of Arabidopsis and rice returned from the space experiment on board SJ-10 experiment to study the effect of microgravity on photoperiod response at the transcriptome level with cDNA microarrays and RNA sequencing. The common points and specificity of flowering control regulation networks of these two important environmental factors will also be analyzed in order to comprehensively and systematically know the effect of microgravity on plant flowering control and provided the direct evidence to uncover the molecular mechanism of photoperiod response of plants under microgravity.