A novel cotton miR7814 targeting GhCNL2 regulates plant defense against Verticillium dahliae infection

Area of Science:

• Plant Molecular Biology
• Plant-Pathogen Interactions
• Gene Regulation

Background:

• MicroRNAs (miRNAs) post-transcriptionally regulate plant resistance (R) genes, including those encoding NBS-LRR proteins.
• The specific resistance mechanisms of miRNA-targeted R gene pairs are not fully understood.
• Understanding these interactions is crucial for developing disease-resistant crops.

Purpose of the Study:

• To investigate the function of a novel miRNA, ghr-miR7814, in regulating plant resistance against Verticillium dahliae infection.
• To elucidate the targeting mechanism of ghr-miR7814 on the GhCNL2 gene.
• To explore the molecular pathways involved in ghr-miR7814-mediated plant defense.

Main Methods:

• GUS reporter assays and 5'-RLM RACE to confirm miRNA-target interaction.
• Virus-induced gene silencing (VIGS) and overexpression assays to study gene function.
• Gene expression analysis of defense-related and biosynthesis genes (e.g., GhPR1, GhICS1).
• DAB staining to assess reactive oxygen species (ROS) levels.

Main Results:

• ghr-miR7814 directly targets and cleaves GhCNL2 mRNA post-transcriptionally.
• Knockdown of ghr-miR7814 enhanced plant resistance to V. dahliae, while overexpression reduced it.
• GhCNL2 knockdown reduced plant resistance and altered the expression of defense genes (GhPR1, GhPR3, GhPR5, GhPDF1.2).
• ROS and salicylic acid (SA) biosynthesis pathways were implicated, with altered H2O2 content and SA-related gene expression in GhCNL2 knockdown plants.

Conclusions:

• The novel ghr-miR7814 negatively regulates plant resistance to V. dahliae by targeting GhCNL2.
• This regulatory pathway likely involves the induction of ROS and SA biosynthesis.
• Findings provide insights into miRNA-mediated plant defense mechanisms against fungal pathogens.