Riboflavin mediates m6A modification targeted by miR408, promoting early somatic embryogenesis in longan

Area of Science:

• Plant Biotechnology
• Molecular Biology
• Developmental Biology

Background:

• Somatic embryogenesis (SE) is crucial for plant regeneration, but the underlying molecular mechanisms are complex.
• MicroRNAs (miRNAs) play vital roles in plant development, including SE.
• The specific function of microRNA408 (miR408) in plant SE remains largely unknown.

Purpose of the Study:

• To elucidate the mechanism of miR408 in promoting early somatic embryogenesis in longan (Dimocarpus longan).
• To identify the target genes and molecular pathways regulated by miR408 during longan SE.
• To investigate the role of miR408 in regulating cell division and differentiation via N6-methyladenosine (m6A) modification.

Main Methods:

• Stable transgenic technology was employed in longan embryogenic calli.
• Overexpression of DlMIR408 (DlMIR408-OE) was used to study miR408 function.
• Riboflavin feeding assays and inhibition experiments were conducted.
• N6-methyladenosine (m6A) modification levels and miRNA homeostasis were analyzed.

Main Results:

• Overexpression of DlMIR408 led to increased dlo-miR408-3p levels, which targeted and downregulated DlNUDT23.
• This regulation promoted riboflavin biosynthesis, decreased flavin mononucleotide (FMN) accumulation, and enhanced m6A modification.
• DlNUDT23 was identified as a key mediator of m6A modification, influencing RNA homeostasis and cell cycle gene expression, thereby promoting cell division and differentiation in longan SE.
• Riboflavin metabolism, DNA replication, GPI-anchor biosynthesis, and the pentose phosphate pathway were associated with miR408-mediated SE.

Conclusions:

• dlo-miR408-3p promotes longan early SE by targeting DlNUDT23, thereby regulating riboflavin biosynthesis and m6A modification.
• This regulatory pathway influences RNA homeostasis and cell cycle gene expression, ultimately promoting cell division and differentiation.
• The findings reveal a novel mechanism for miR408 in plant somatic embryogenesis, highlighting the interplay between miRNA, riboflavin metabolism, and epigenetic modification.