Wang Kun, Wang Xin, Li Ming, Shi Tao, Yang Pingfang
Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, China.
College of Life Sciences, Wuhan University, Wuhan, China.
Plant Mol Biol. 2017 Sep;95(1-2):89-98. doi: 10.1007/s11103-017-0638-0. Epub 2017 Jul 22.
In this study, we sequenced and analyzed the expression and evolution of rice miRNA genes participating pollen-pistil interaction that is crucial to rice yield. Pollen-pistil interaction is an essential reproductive process for all flowering plants. While microRNAs (miRNAs) are important noncoding small RNAs that regulate mRNA levels in eukaryotic cells, there is little knowledge about which miRNAs involved in the early stages of pollen-pistil interaction in rice and how they evolve under this conserved process. In this study, we sequenced the small RNAs in rice from unpollinated pistil (R0), pistil from 5 min and 15 min after pollination, respectively, to identify known and novel miRNAs that are involved in this process. By comparing the corresponding mRNA-seq dataset, we identified a group of miRNAs with strong negative expression pattern with their target genes. Further investigation of all miRNA loci (MIRNAs) across 1083 public rice accessions revealed significantly reduced genetic diversity in MIRNAs with strong negative expression of their targets when comparing to those with little or no impact on targets during pollen-pistil interaction. Annotation of targets suggested that those MIRNAs with strong impact on targets were pronounced in cell wall related processes such as xylan metabolism. Additionally, plant conserved miRNAs, such as those with functions in gibberellic acid, auxin and nitrate signaling, were also with strong negative expression of their targets. Overall, our analyses identified key miRNAs participating pollen-pistil interaction and their evolutionary patterns in rice, which can facilitate the understanding of molecular mechanisms associated with seed setting.
在本研究中，我们对参与水稻产量关键的花粉 - 雌蕊相互作用的水稻miRNA基因进行了测序，并分析了其表达和进化情况。花粉 - 雌蕊相互作用是所有开花植物必不可少的生殖过程。虽然微小RNA（miRNA）是调节真核细胞中mRNA水平的重要非编码小RNA，但对于水稻花粉 - 雌蕊相互作用早期阶段涉及哪些miRNA以及它们在这个保守过程中如何进化，我们了解甚少。在本研究中，我们分别对未授粉雌蕊（R0）、授粉后5分钟和15分钟的雌蕊中的小RNA进行了测序，以鉴定参与此过程的已知和新型miRNA。通过比较相应的mRNA-seq数据集，我们鉴定出一组与其靶基因具有强烈负表达模式的miRNA。对1083份公共水稻种质中所有miRNA基因座（MIRNA）的进一步研究表明，与那些在花粉 - 雌蕊相互作用期间对靶标影响很小或没有影响的MIRNA相比，其靶标具有强烈负表达的MIRNA的遗传多样性显著降低。靶标的注释表明，那些对靶标有强烈影响的MIRNA在细胞壁相关过程（如木聚糖代谢）中表现突出。此外，植物保守的miRNA，如那些在赤霉素、生长素和硝酸盐信号传导中起作用的miRNA，其靶标也具有强烈的负表达。总体而言，我们的分析确定了参与水稻花粉 - 雌蕊相互作用的关键miRNA及其进化模式，这有助于理解与结实相关的分子机制。
