Stage-Specific RNA Turnover Drives Small RNA Dynamics in Arabidopsis – Colletotrichum Interactions

The hemibiotrophic fungus Colletotrichum higginsianum infects Arabidopsis thaliana through three stages: appressorial penetration, biotrophy, and necrotrophy. However, the dynamics of fungal and plant sRNA populations across these three stages has not been elucidated.

Using high-throughput sequencing, we profiled sRNAs from A. thaliana and C. higginsianum during in planta appressorium (PA), biotrophic (BP), and necrotrophic (NP) phases, and compared them to fungal mycelia (MY) and in vitro appressoria (VA). Our analyses revealed stage-specific patterns in sRNA accumulation in both the plant and the pathogen. In C. higginsianum, sRNAs were dominated by 29 nt species in PA, BP, MY, and VA, but shifted to 18 nt in NP, consistent with RNA degradation during host cell death.