Lu Dongdong, Feng Li, Zhai Jixian, Li Bosheng, Xi Mengli
Key Laboratory of Forest Genetics and Biotechnology of Ministry of Education, Nanjing Forestry University, Nanjing, 210037, China; Institute of Advanced Agricultural Sciences, Peking University, Weifang, 261325, China; Institute of Plant and Food Science, Department of Biology, Southern University of Science and Technology, Shenzhen, 518055, China.
Institute of Advanced Agricultural Sciences, Peking University, Weifang, 261325, China; Institute of Plant and Food Science, Department of Biology, Southern University of Science and Technology, Shenzhen, 518055, China.
Biochem Biophys Res Commun. 2022 May 21;605:97-103. doi: 10.1016/j.bbrc.2022.03.076. Epub 2022 Mar 17.
MicroRNAs (miRNAs) and small interfering RNAs (siRNAs) are crucial for plant growth and development via mediating post-transcriptional gene silencing. In wild-type Arabidopsis, DICER-LIKE 2 (DCL2)-dependent 22-nt siRNAs are rare, whereas DCL1 and DCL4-dependent 21-nt miRNAs and siRNAs are highly abundant. DCL4 naturally inhibits DCL2 in producing abundant 22-nt siRNAs from endogenous transcripts, but whether DCL1 suppresses endogenous 22-nt siRNA production and the extent of repression are still unknown. Here, we report that DCL1 and DCL2 cleaved both miRNA precursors and coding transcript-derived double-stranded RNAs. In a dcl1 dcl4 double mutant, massive 22-nt siRNAs were produced from endogenous protein-coding genes (genic siRNAs). Compared with wild-type, the 22-nt genic siRNAs derived from the Nitrate Reductase 1 (NIA1), NIA2, DIACYLGLYCEROL ACYLTRANSFERASES 3 (DGAT3), SUPPRESSOR OF MAX2 1-LIKE 5 (SMXL5), and SMXL4 in dcl1 dcl4 increased up to 95%. Our analysis further indicated that the 22-nt genic siRNAs in dcl1 dcl4 were mainly loaded into ARGONAUTE 1 (AGO1) or AGO2. Thus, our results demonstrated that both DCL1 and DCL4 safeguard post-transcriptional gene silencing, preventing the production of DCL2-dependent 22-nt genic siRNAs from disrupting plant growth and development.
微小RNA（miRNA）和小干扰RNA（siRNA）通过介导转录后基因沉默对植物生长发育至关重要。在野生型拟南芥中，依赖于Dicer样蛋白2（DCL2）的22核苷酸siRNA很少见，而依赖于DCL1和DCL4的21核苷酸miRNA和siRNA则高度丰富。DCL4天然抑制DCL2从内源性转录本产生大量22核苷酸siRNA，但DCL1是否抑制内源性22核苷酸siRNA的产生以及抑制程度仍不清楚。在这里，我们报告DCL1和DCL2都能切割miRNA前体和编码转录本衍生的双链RNA。在dcl1 dcl4双突变体中，从内源性蛋白质编码基因（基因siRNA）产生了大量22核苷酸siRNA。与野生型相比，dcl1 dcl4中来自硝酸还原酶1（NIA1）、NIA2、二酰甘油酰基转移酶3（DGAT3）、MAX2抑制因子1样5（SMXL5）和SMXL4的22核苷酸基因siRNA增加了95%。我们的分析进一步表明，dcl1 dcl4中的22核苷酸基因siRNA主要加载到AGO1或AGO2中。因此，我们的结果表明，DCL1和DCL4都能保障转录后基因沉默机制，防止依赖DCL2的22核苷酸基因siRNA的产生干扰植物的生长发育。
