MicroRNA319-mediated gene regulatory network impacts leaf development and morphogenesis in poplar

Area of Science:

• Plant Molecular Biology
• Plant Genetics
• Forestry Science

Background:

• MicroRNA319 (miR319) is recognized for its role in plant leaf development.
• Understanding miR319a's specific functions and regulatory networks in poplar species is crucial.

Purpose of the Study:

• To investigate the function of miR319a in poplar leaf development.
• To elucidate the gene regulatory network controlled by miR319a in poplars.

Main Methods:

• Over-expression of miR319a in *Populus alba* × *Populus glandulosa*.
• Analysis of phenotypic changes and cellular structures in transgenic poplars.
• Gene expression analysis using RNA-seq and psRNATarget prediction.
• Construction of a gene regulatory network using the Top-down graphic Gaussian model (GGM) algorithm.

Main Results:

• Over-expression of miR319a led to dwarfism, narrow leaves, and serrated margins.
• Transgenic leaves exhibited increased cell layers in vascular bundles and bundle sheaths, indicating enhanced lignification.
• Three *TCP* genes were identified as differentially expressed targets of miR319a.
• A three-layered gene regulatory network mediated by miR319a was constructed, highlighting its role in lignin biosynthesis, leaf development, and photosynthesis via specific regulatory modules.

Conclusions:

• miR319a plays a significant role in regulating poplar leaf morphology and development.
• The miR319a-TCP gene network is a key regulator of lignin biosynthesis, leaf differentiation, and photosynthesis in poplars.