Professor Shih-Shun Lin from the Institute of Biotechnology at National Taiwan University has dedicated 16 years to investigating how plant viruses disrupt the RNA silencing mechanism. His team’s groundbreaking research has been accepted for publication in Nature Communications. RNA silencing is a vital defense mechanism in plants against viral infections. To counteract this defense, viruses have evolved specialized suppressors that inhibit RNA silencing.
Professor Lin has long used the turnip mosaic virus (TuMV) as a model virus and Arabidopsis as a model plant for studying this process. His team discovered that the viral suppressor HC-ProTu of TuMV strongly inhibits HEN1, a key methyltransferase in the RNA silencing pathway. This inhibition leads to the accumulation of unmethylated microRNAs (unMet-miRNAs). However, the scientific community has believed for years that HC-ProTu primarily suppresses RNA silencing by sequestering miRNAs and preventing their loading into AGO1, another key protein in the RNA silencing machinery. To challenge this long-standing theory, Professor Lin required extensive time and robust evidence to demonstrate that HC-ProTu possesses additional RNA silencing suppression capabilities.
Since joining NTU’s Institute of Biotechnology in 2008, Professor Lin and his research team have worked tirelessly to uncover the unique properties of HC-ProTu. They discovered that its ability to inhibit HEN1 was significantly stronger than that of HC-Pro from other viruses, such as the Zucchini yellow mosaic virus (ZYMV). Specifically, HC-ProTu could suppress HEN1 activity by 50%, while HC-ProZy could only reduce methylation activity by 20%. This discovery highlighted that different Potyviruses have varying requirements for inhibiting HEN1 activity in plants.
Furthermore, the team found that when unMet-miRNAs enter AGO1, they are recognized by HESO1, triggering autophagy-mediated degradation of the unMet-miRNA-AGO1 complex. As a result, HC-ProTu causes greater instability of AGO1 in plant cells than HC-ProZy. Transcriptomic analyses further confirmed that HC-ProTu has a stronger RNA silencing suppression effect than HC-ProZy.
During the review process for Nature Communications, an autophagy expert strongly objected to the proposed theory of autophagic AGO1 degradation. To address these concerns, the team conducted two additional years of experiments, working closely with the Electron Microscopy Facilities at NTU and Academia Sinica to obtain critical data. Immunoelectron microscopy provided key evidence that HC-ProTu, ATG8a (an autophagy marker), and AGO1 colocalized within autophagosomes. This compelling evidence ultimately led to the acceptance of their study by Nature Communications in December 2024.
Through years of dedication and overcoming numerous challenges, Professor Lin and his team successfully demonstrated a novel function of HC-ProTu, earning recognition from a top-tier international journal. This achievement marks a significant breakthrough in plant virology and highlights the power of persistence and teamwork. Faced with rigorous scrutiny from experts, the team chose to confront this challenge head-on, supplementing their research with meticulous experimentation and robust data to persuade reviewers, ultimately redefining a long-standing scientific paradigm.
This accomplishment serves as inspiration, demonstrating that scientific exploration requires time, perseverance, and the courage to challenge conventional wisdom. Looking ahead, this research is expected to motivate young scholars to pursue plant science from innovative perspectives to solve unresolved mysteries. Additionally, further investigation into the RNA silencing mechanism could lead to breakthroughs in developing virus-resistant crops for agriculture. Regardless of the challenges ahead, maintaining faith and a steadfast commitment to scientific inquiry will ultimately illuminate the path forward, bringing hope and new possibilities in the field of plant biology.
The Thesis's Official Link: https://www.nature.com/articles/s41467-025-56320-z?utm_source=rct_congratemailt&utm_medium=email&utm_campaign=oa_20250313&utm_content=10.1038/s41467-025-56320-z
Relevant Refernce: https://www.asiaresearchnews.com/content/battle-between-resilient-plants-and-cunning-viruses-strategies-attack-and-defense
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