Kruse Colin P S, Meyers Alexander D, Basu Proma, Hutchinson Sarahann, Luesse Darron R, Wyatt Sarah E
Department of Environmental and Plant Biology, Ohio University, Athens, OH, USA.
Interdisciplinary Molecular and Cellular Biology Program, Ohio University, Athens, OH, USA.
BMC Plant Biol. 2020 May 27;20(1):237. doi: 10.1186/s12870-020-02392-6.
Understanding of gravity sensing and response is critical to long-term human habitation in space and can provide new advantages for terrestrial agriculture. To this end, the altered gene expression profile induced by microgravity has been repeatedly queried by microarray and RNA-seq experiments to understand gravitropism. However, the quantification of altered protein abundance in space has been minimally investigated.
Proteomic (iTRAQ-labelled LC-MS/MS) and transcriptomic (RNA-seq) analyses simultaneously quantified protein and transcript differential expression of three-day old, etiolated Arabidopsis thaliana seedlings grown aboard the International Space Station along with their ground control counterparts. Protein extracts were fractionated to isolate soluble and membrane proteins and analyzed to detect differentially phosphorylated peptides. In total, 968 RNAs, 107 soluble proteins, and 103 membrane proteins were identified as differentially expressed. In addition, the proteomic analyses identified 16 differential phosphorylation events. Proteomic data delivered novel insights and simultaneously provided new context to previously made observations of gene expression in microgravity. There is a sweeping shift in post-transcriptional mechanisms of gene regulation including RNA-decapping protein DCP5, the splicing factors GRP7 and GRP8, and AGO4,. These data also indicate AHA2 and FERONIA as well as CESA1 and SHOU4 as central to the cell wall adaptations seen in spaceflight. Patterns of tubulin-α 1, 3,4 and 6 phosphorylation further reveal an interaction of microtubule and redox homeostasis that mirrors osmotic response signaling elements. The absence of gravity also results in a seemingly wasteful dysregulation of plastid gene transcription.
The datasets gathered from Arabidopsis seedlings exposed to microgravity revealed marked impacts on post-transcriptional regulation, cell wall synthesis, redox/microtubule dynamics, and plastid gene transcription. The impact of post-transcriptional regulatory alterations represents an unstudied element of the plant microgravity response with the potential to significantly impact plant growth efficiency and beyond. What's more, addressing the effects of microgravity on AHA2, CESA1, and alpha tubulins has the potential to enhance cytoskeletal organization and cell wall composition, thereby enhancing biomass production and growth in microgravity. Finally, understanding and manipulating the dysregulation of plastid gene transcription has further potential to address the goal of enhancing plant growth in the stressful conditions of microgravity.
了解重力感知与响应对于人类在太空的长期居住至关重要，并且可为陆地农业带来新优势。为此，微阵列和RNA测序实验反复探究了微重力诱导的基因表达谱变化，以了解向地性。然而，对太空环境中蛋白质丰度变化的定量研究极少。
蛋白质组学（iTRAQ标记的液相色谱-串联质谱法）和转录组学（RNA测序）分析同时对国际空间站上生长三天的黄化拟南芥幼苗及其地面对照幼苗的蛋白质和转录本差异表达进行了定量。对蛋白质提取物进行分级分离以分离可溶性蛋白和膜蛋白，并进行分析以检测差异磷酸化的肽段。总共鉴定出968个差异表达的RNA、107个可溶性蛋白和103个膜蛋白。此外，蛋白质组学分析还鉴定出16个差异磷酸化事件。蛋白质组学数据提供了新的见解，同时为先前关于微重力下基因表达的观察提供了新的背景信息。基因调控的转录后机制发生了全面转变，包括RNA去帽蛋白DCP5、剪接因子GRP7和GRP8以及AGO4。这些数据还表明AHA2和FERONIA以及CESA1和SHOU4是太空飞行中细胞壁适应性变化的核心。微管蛋白-α 1、3、4和6的磷酸化模式进一步揭示了微管与氧化还原稳态之间的相互作用，这与渗透反应信号元件相似。重力的缺失还导致质体基因转录出现看似浪费的失调。
从暴露于微重力的拟南芥幼苗收集的数据集揭示了对转录后调控、细胞壁合成、氧化还原/微管动力学和质体基因转录的显著影响。转录后调控改变的影响代表了植物微重力响应中一个未被研究的元素，有可能显著影响植物生长效率及其他方面。此外，解决微重力对AHA2、CESA1和α微管蛋白的影响有可能增强细胞骨架组织和细胞壁组成，从而提高微重力下的生物量生产和生长。最后，了解和控制质体基因转录的失调对于实现微重力应激条件下增强植物生长的目标具有进一步的潜力。
