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An insight into the viroid-induced immune signaling pathways in plants

Year: 2025

Type: article

Abstract: Since the discovery of viroids as smallest RNA pathogens causing plant infection, researchers have been fascinated by how these tiny RNAs invade plants and cause disease. Initially, it was thought that viroids caused disease through their interactions with the host's proteins. However, later studies suggested that RNA interference (RNAi) might play a role in viroid pathogenesis. There's still uncertainty about whether viroids can be detected at the cell membrane by specific receptors, similar to how bacterial and fungal pathogens are recognized. Hence, a key question has been whether viroid can act as Damage-associated molecular patterns (DAMPs) or Pathogen-associated molecular patterns (PAMPs), which could trigger the plant's immune responses, remained a debated topic. Recent findings, including advancements in transcriptomics, show that the plant's innate immune responses can be activated during viroid infection. The discovery of virus-derived double-stranded RNA (dsRNA) acting as DAMPs, which triggers immune responses through somatic embryogenesis receptor-like kinase 1 (SERK1)-mediated plasmodesmal immunity, suggests that viroids might indeed be recognized at the plant cell membrane. This review aims to clarify how viroids are detected by the plant immune system, the immune responses triggered by their entry, and the effects of viroid infection on plant cellular and molecular processes. Understanding RNA-triggered immunity related to viroids can help in developing plants that are resistant or tolerant to these pathogens.

Source: Discover Plants.

DOI: 10.1007/s44372-025-00191-7