MicroRNAs regulate common bean (Phaseolus vulgaris L.) immunity during Colletotrichum lindemuthianum infection

Abstract

Anthracnose, caused by the hemibiotrophic fungus Colletotrichum lindemuthianum, poses a major threat to common bean (Phaseolus vulgaris L.) production, leading to substantial yield losses worldwide. Understanding the molecular mechanisms underlying plant defense is essential for developing genetic resistance strategies. Among these mechanisms, microRNAs (miRNAs) play a crucial role in post-transcriptional gene regulation, modulating key pathways involved in plant immunity. This study investigates the expression dynamics of miRNAs in P. vulgaris during C. lindemuthianum infection and predicts their potential regulatory targets. RT-qPCR was employed to assess the temporal expression profiles of selected miRNAs, revealing distinct regulatory patterns throughout pathogen establishment and disease progression. Target prediction supported their potential roles in modulating host defense. The downregulation of miR160abc-5p and miR393abcd-5p suggests their involvement in auxin signaling pathways, essential for balancing growth and immunity responses. Interestingly, miR2118-3p and miR5374 were upregulated at 48 h after infection (hai), while miR2118-3p expression declined at 96 hai in inoculated plants, indicating stage-specific. Both miR2118-3p and the legume-specific miR5374 were predicted to target NBS-LRR and LRR resistance genes, suggesting roles in the fine-tuning or suppression of immune responses. The expression of miR5374, in particular, may facilitate pathogen colonization by repressing key defense components. This study provides valuable data on the expression patterns of specific miRNAs and identifies their potential targets, suggesting their involvement in the P. vulgaris response to C. lindemuthianum. These findings contribute to a more comprehensive understanding of the molecular mechanisms governing plant-pathogen interactions.