Adaptive evolution and functional innovation of Populus-specific recently evolved microRNAs

Area of Science:

• Evolutionary biology
• Genomics
• Plant science

Background:

• Lineage-specific microRNAs (miRNAs) evolve rapidly, but their origins and functions are debated.
• Populus-specific miRNAs arose after a salicoid-specific whole-genome duplication event.

Purpose of the Study:

• To investigate the origin, evolution, and adaptive roles of Populus-specific miRNAs.
• To analyze miRNA and gene expression, divergence rates, and adaptive variation in Populus species.

Main Methods:

• RNA sequencing for miRNA and gene expression profiling across six tissues.
• Analysis of natural populations of Populus trichocarpa and related species.
• Examination of single nucleotide polymorphisms in miRNA precursors.

Main Results:

• Populus-specific miRNAs originating in 5' UTRs exhibit higher expression and correlate with host genes.
• A higher proportion of these miRNAs target genes duplicated during salicoid duplication.
• Significant population differentiation was observed in Populus-specific miRNA precursors.
• The MIR6445 family was characterized, producing phased small interfering RNAs from NAC mRNAs.

Conclusions:

• Populus-specific miRNAs provide evolutionary insights into their birth and function.
• These miRNAs are implicated in genome maintenance, local adaptation, and functional innovation in Populus.
• The study highlights the dynamic evolution and adaptive significance of lineage-specific miRNAs.