The laboratory of Li Lei, College of Modern Agriculture, Peking University, discovered the genetic mechanism of the origin of miRNA in angiosperms

On October 13, 2022, the research group of researcher Li Lei, State Key Laboratory of Protein and Plant Gene Research and School of Modern Agriculture, Peking University, published an online publication entitled "Miniature inverted-repeat transposable elements drive rapid microRNA diversification in" in the journal Molecular Biology and Evolution angiosperms"
.
This study discovered the mechanism by which miniature reverse repeating transposons (MITEs) drive the rapid diversification of miRNAs in angiosperms, providing a new model
for the study of plant miRNA origin and evolution.

MiRNA is a class of single-stranded nucleic acid regulators that are widely present in plants and animals
.
In the past 20 years, the biochemical process of plant miRNA synthesis and the function of miRNAs have been studied in depth, but the genetic mechanism of miRNAs from de novo origin is still unresolved
.
Using the plant miRNA database (https://pmiren.
com/) constructed in the early stage, the miRNA sites in 21 representative plants were analyzed in detail, and miRNAs generated by three models, including target gene reverse repeat, LTR transposon and MITE, were systematically identified, and found that miRNAs in angiosperms were mainly derived from MITE
。 Through the comprehensive analysis of genomic and transcriptome data, a model of the hairpin structure formed by the transcription of medium-length MITE located in the intron with the host gene was proposed, and the new miRNA was formed after being recognized by the cutting complex with Dicer-like protein as the core
.
It was further found that the outbreak of Mutator in dicots and PIF/Harbinger and Tc1/Mariner superfamily MITE in monocots was the main reason for the sharp increase in miRNA in angiosperms (Figure 1).

Finally, by analyzing the function and expression patterns of miRNA target genes, it was found that miRNAs originating from MITE preferentially regulate genes
related to environmental stress and adaptation.
These findings elucidate the genetic mechanism by which angiosperm miRNAs are produced de novo by involuntary mini-transposons, revealing the possibility of
newly formed miRNAs being selected for improved environmental adaptability of plants.

Figure I.
A model of MITE-miRNA evolution in angiosperms

Guo Zhonglong, a doctoral graduate of Peking University and currently working at Nanjing Forestry University, is the first author of the paper, and researcher Li Lei of Peking University and Yang Xiaozeng, researcher of Beijing Academy of Agriculture and Forestry Sciences, are co-corresponding authors
of the paper.
Doctoral students Kuang Zheng, Tao Yihan, Wan Miaomiao, postdoctoral Hao Chen, Dr.
Wang Haotian of Kunming Institute of Zoology and Dr.
Shen Fei of Beijing Academy of Agriculture and Forestry Sciences provided help
in the work.
The "Polaris" high-performance computing platform of the Joint Center for Life Sciences of Peking University provided technical support
.
This work was supported
by the National Key Research and Development Program of China, the National Natural Science Foundation of China, and the Peking University-Tsinghua Joint Center for Life.