Emerging roles of plant microRNAs during Colletotrichum spp. infection

Main conclusion This review provides valuable insights into plant molecular regulatory mechanisms during fungus attacks, highlighting potential miRNA candidates for future disease management. Plant defense responses to biotic stress involve intricate regulatory mechanisms, including post-transcriptional regulation of genes mediated by microRNAs (miRNAs). These small RNAs play a vital role in the plant's innate immune system, defending against viral, bacterial, and fungal attacks. Among the plant pathogenic fungi, Colletotrichum spp. are notorious for causing anthracnose, a devastating disease affecting economically important crops worldwide. Understanding the molecular machinery underlying the plant immune response to Colletotrichum spp. is crucial for developing tools to reduce production losses. In this comprehensive review, we examine the current understanding of miRNAs associated with plant defense against Colletotrichum spp. We summarize the modulation patterns of miRNAs and their respective target genes. Depending on the function of their targets, miRNAs can either contribute to host resistance or susceptibility. We explore the multifaceted roles of miRNAs during Colletotrichum infection, including their involvement in R-gene-dependent immune system responses, hormone-dependent defense mechanisms, secondary metabolic pathways, methylation regulation, and biosynthesis of other classes of small RNAs. Furthermore, we employ an integrative approach to correlate the identified miRNAs with various strategies and distinct phases of fungal infection. This study provides valuable insights into the current understanding of plant miRNAs and their regulatory mechanisms during fungus attacks.