Guangdong Provincial Key Laboratory for Plant Epigenetics, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518060, Guangdong Province, China.
State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, CAS Center for Excellence in Molecular Plant Sciences, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
Plant Physiol. 2018 May;177(1):381-397. doi: 10.1104/pp.17.01714. Epub 2018 Mar 19.
Ribosome biogenesis is crucial for plant growth and environmental acclimation. Processing of ribosomal RNAs (rRNAs) is an essential step in ribosome biogenesis and begins with transcription of the rDNA. The resulting precursor-rRNA (pre-rRNA) transcript undergoes systematic processing, where multiple endonucleolytic and exonucleolytic cleavages remove the external and internal transcribed spacers (ETS and ITS). The processing sites and pathways for pre-rRNA processing have been deciphered in and, to some extent, in , mammalian cells, and Arabidopsis (). However, the processing sites and pathways remain largely unknown in crops, particularly in monocots such as rice (), one of the most important food resources in the world. Here, we identified the rRNA precursors produced during rRNA biogenesis and the critical endonucleolytic cleavage sites in the transcribed spacer regions of pre-rRNAs in rice. We further found that two pre-rRNA processing pathways, distinguished by the order of 5' ETS removal and ITS1 cleavage, coexist in vivo. Moreover, exposing rice to chilling stress resulted in the inhibition of rRNA biogenesis mainly at the pre-rRNA processing level, suggesting that these energy-intensive processes may be reduced to increase acclimation and survival at lower temperatures. Overall, our study identified the pre-rRNA processing pathway in rice and showed that ribosome biogenesis is quickly inhibited by low temperatures, which may shed light on the link between ribosome biogenesis and environmental acclimation in crop plants.
核糖体生物发生对于植物的生长和环境适应至关重要。核糖体 RNA(rRNA)的加工是核糖体生物发生的一个重要步骤,始于 rDNA 的转录。所得的前体 rRNA(pre-rRNA)转录本经历系统加工,其中多个内切核酸酶和外切核酸酶切割去除外部和内部转录间隔区(ETS 和 ITS)。在 和 ,以及在哺乳动物细胞和拟南芥()中,已经破译了 pre-rRNA 加工的加工位点和途径。然而,在作物中,特别是在单子叶植物如水稻()中,这些加工位点和途径在很大程度上仍然未知,水稻是世界上最重要的粮食资源之一。在这里,我们鉴定了在 rRNA 生物发生过程中产生的 rRNA 前体,以及 pre-rRNA 转录间隔区中关键的内切核酸酶切割位点。我们还发现,两种 pre-rRNA 加工途径在体内共存,其特征在于 5'ETS 去除和 ITS1 切割的顺序。此外,将水稻暴露于冷胁迫会导致 rRNA 生物发生主要在 pre-rRNA 加工水平上受到抑制,这表明这些需要大量能量的过程可能会减少,以增加在较低温度下的适应和生存能力。总体而言,我们的研究鉴定了水稻中的 pre-rRNA 加工途径,并表明核糖体生物发生会被低温迅速抑制,这可能揭示了核糖体生物发生与作物植物环境适应之间的联系。