The miR396d-PagGRF20-PagXTH5 module regulates salt tolerance in poplar

Area of Science:

• Plant Biology
• Molecular Biology
• Genetics

Background:

• Salinity is a major constraint on biomass production in perennial trees.
• Cell-wall remodeling's role in salt tolerance is not well understood.
• Understanding salt tolerance mechanisms is crucial for agriculture and bioenergy.

Purpose of the Study:

• To elucidate the regulatory module controlling salt tolerance in poplar.
• To investigate the roles of miR396d, PagGRF20, and PagXTH5 in salinity stress.
• To identify potential genetic strategies for enhancing salt resilience in trees.

Main Methods:

• Gene expression analysis (transcriptome).
• Chromatin accessibility assays (ATAC-seq).
• Transcription factor binding assays (DAP-seq).
• Generation and analysis of transgenic poplar plants.

Main Results:

• Identified the miR396d-PagGRF20-PagXTH5 module as key to poplar salt tolerance.
• PagGRF20, an atypical GRF, negatively impacts stress tolerance and leaf growth.
• miR396d overexpression or paggrf20 knockout improved salt tolerance, reduced ROS, and increased antioxidant enzyme activity.
• PagXTH5, a negative regulator, is a direct target of the miR396d-PagGRF20 module.
• PagGRF20 and PagRAP2.3 synergistically activate PagXTH5 expression.

Conclusions:

• The miR396d-PagGRF20-PagXTH5 axis balances growth and stress responses in poplar.
• This module provides a promising genetic target for breeding salt-resilient bioenergy poplar.
• Optimizing this pathway can enhance biomass accumulation while improving stress survival.