MicroRNAs (miRNAs) regulate many biological processes such as development, 
metabolism, and others. They are processed from their primary transcripts called 
primary miRNA transcripts (pri-miRNAs) by the processor complex containing the 
RNAse III enzyme, DICER-LIKE1 (DCL1), in plants. Consequently, miRNA biogenesis 
is controlled through altering pri-miRNA accumulation and processing, which is 
crucial for plant development and adaptation to environmental changes. Plant 
pri-miRNAs are transcribed by DNA-dependent RNA polymerase II (Pol II) and their 
levels are determined through transcription and degradation, whereas pri-miRNA 
processing is affected by its structure, splicing, alternative splicing, loading 
to the processor and the processor activity, which involve in many accessory 
proteins. Here, we summarize recent progresses related to pri-miRNA 
transcription, stability, and processing in plants.