CRISPR/Cas-mediated in planta gene targeting: current advances and challenges.

Gene targeting can be used to make modifications at a specific region in a plant's genome and create high-precision tools for plant biotechnology and breeding. However, its low efficiency is a major barrier to its use in plants. The discovery of CRISPR (clustered regularly interspaced short palindromic repeats)-Cas-based site-specific nucleases capable of inducing double-strand breaks in desired loci resulted in the development of novel approaches for plant gene targeting.

AAR2, a conserved splicing factor in eukaryotes, acts in microRNA biogenesis.

MicroRNAs (miRNAs) play an essential role in plant growth and development, and as such, their biogenesis is fine-tuned via regulation of the core microprocessor components. Here, we report that AAR2, a homolog of a U5 snRNP assembly factor in yeast and humans, not only acts in splicing but also promotes miRNA biogenesis. AAR2 interacts with the microprocessor component hyponastic leaves 1 (HYL1) in the cytoplasm, nucleus, and dicing bodies.

Light Triggers the miRNA-Biogenetic Inconsistency for De-etiolated Seedling Survivability in Arabidopsis thaliana.

The shift of dark-grown seedlings into light causes enormous transcriptome changes followed by a dramatic developmental transition. Here, we show that microRNA (miRNA) biogenesis also undergoes regulatory changes during de-etiolation. Etiolated seedlings maintain low levels of primary miRNAs (pri-miRNAs) and miRNA processing core proteins, such as Dicer-like 1, SERRATE, and HYPONASTIC LEAVES 1, whereas during de-etiolation both pri-miRNAs and the processing components accumulate to high levels.

A Quick HYL1-Dependent Reactivation of MicroRNA Production Is Required for a Proper Developmental Response after Extended Periods of Light Deprivation.

Light is the most influential environmental stimulus for plant growth. In response to deficient light, plants reprogram their development to adjust their growth in search for a light source. A fine reprogramming of gene expression orchestrates this adaptive trait.

miRNA Biogenesis: A Dynamic Pathway.

MicroRNAs (miRNAs) modulate plant homeostasis through the inactivation of specific mRNAs, especially those encoding transcription factors. A delicate spatial/temporal balance between a miRNA and its targets is central to achieving the appropriate biological outcomes. In this review we discuss our growing understanding of the dynamic regulation of miRNA biogenesis.