玉米小RNA作用机制及其与膜结合多核糖体关系的探究

miRNA and phasiRNA are a class of small RNAs that play important regulatory roles in the growth and development of plants and in response to environmental conditions. Since the discovery of small RNAs in the last century, the mechanism of biogenesis, degradation and action of small RNAs have been studied and now relatively clear, however, the subcellular location in which these processes take place is largely unknown. Recent studies have reveled that miRNAs are enriched in membrane-bound poly-ribosomes in Arabidopsis thaliana and that the biogenesis of phasiRNAs is also associated with membrane-bound polyribosomes. Maize is a very important food and economic crop, and the maize genome contains many MIRNA genes, as well as an abundant PHAS genes. Taking maize as a model to study the location of action of miRNAs and phasiRNA biosynthesis, this study aims to reveal the conservativeness of small RNA biosynthesis in plants and to promote the future study of small RNA mechanism and even provide new theoretical basis for crop improvement. In addition, we use ribo-seq data to analyze the types and characteristics of synthetic proteins on membrane-bound polysomes of maize young tassels for the first time. This study provides a theoretical basis for studying the physiological activities and regulatory mechanisms during maize reproductive phases.

miRNA与phasiRNA是一类在植物的生长发育和响应外界环境条件过程中发挥重要调控作用的小RNA分子。自上世纪被发现报道以来，尽管小RNA的合成、降解及活性机制研究的已经比较清晰，但是对于这些过程在细胞内发生的场所了解甚少。最新的研究以拟南芥为材料证实miRNA在膜结合核糖体上富集，phasiRNA的发生也与膜结合核糖体相关。玉米是一种非常重要的粮食和经济作物，玉米基因组中含有许多MIRNA基因，以及更为丰富的PHAS基因。本研究以玉米为模型研究miRNA的作用场所以及phasiRNA合成的部位，有助于揭示小RNA相关机制发生在植物中的保守性，促进今后对小RNA机理的研究甚至为作物的性状改良提供新的理论依据。此外本研究利用ribo-seq的数据，首次尝试解析玉米雄穗中膜结合多核糖体上合成蛋白类型与特征，为研究玉米生殖期的生理活动和调控机制提供理论基础。

miRNA与phasiRNA是在植物的生长发育和响应外界环境条件过程中发挥重要调控作用的非编码小RNA分子。自上世纪被发现报道以来，尽管小RNA的合成、降解及活性机制研究的已经比较清晰，但是对于这些过程在细胞内发生的场所了解甚少。最新的研究以拟南芥为材料证实了miRNA在膜结合核糖体上富集，phasiRNA的发生也与膜结合核糖体相关。玉米是一种非常重要的粮食和经济作物，玉米基因组中含有许多MIRNA基因，以及更为丰富的PHAS基因。本研究以玉米生殖组织雄穗为材料，对细胞亚细胞组分进行高质量分离，并结合小RNA文库、转录组、降解组和核糖体保护文库等高通量组学手段，发现单子叶植物中miRNA的作用场所以及phasiRNA生成的起始也主要发生在膜结合多聚核糖体上，揭示了小RNA相关机制在植物中的保守性。本研究还揭示了禾本科生殖组织中丰富的phasiRNA在亚细胞分布中的差异，成熟的24-nt phasiRNA几乎与多聚核糖体无关而21-nt phasiRNA与它们可能的靶基因在膜结合多聚核糖体上有明显的富集，为两类不同长度的phasiRNA在植物体内的作用机制提供新的线索。