New research from Vrije Universiteit Amsterdam, RIKEN and the University of Cambridge challenges decades-old assumptions, pointing the way to genetic transformation of one the most important symbionts.
More than 70% of all land plants depend on a hidden underground partnership with arbuscular mycorrhizal (AM) fungi, organisms that help feed plants, boost crop health, and lock away large amounts of carbon in the soil. Despite their vital role in ecosystems and agriculture, these fungi have remained genetic black boxes: impossible to genetically modify, keeping a lot of their biological secrets locked away.
“Why? Because AM fungi are biological oddities” said VU Amsterdam ecologist, Vasilis Kokkoris. “They grow not as many cells but as a single, continuous gigantic cell, filled with nutrients, nuclei, and other organelles: a coenocytic, multinucleate network that lives only in symbiosis with plants. This makes it notoriously difficult to get foreign DNA in, let alone edit it in a reliable, controlled way.”
New strategies and promising leads
In a new review published in Trends in Microbiology, researchers argue that with today’s advanced gene editing technologies and a wave of recent biological insights, the time is ripe to revisit the challenge. CRISPR, microinjection, protoplast transformation: tools once thought irrelevant to AM fungi could now play a key role in future research.
The authors outline strategies for overcoming major hurdles, from DNA delivery to genome integration in a multinucleate environment. They also highlight promising leads that can help overcome limitations imposed by the AM fungal unique cell biology, including emerging methods that allow us to grow and manipulate AM fungi independently of a host. The review also identifies key unanswered questions and critical research gaps that must be addressed to unlock deeper insights into the genomes of these important plant symbionts.
Finally potential to overcome barriers
“It's been almost 20 years since the last attempts to genetically transform AM fungi, and our understanding of their biology has developed so much,” Midge Woodward, VU Amsterdam, explains. “Combined with new gene editing tools like CRISPR, there’s great potential to finally overcome the barriers that once made genetic manipulation of AM fungi seem impossible.”
Unlocking genetic transformation in AM fungi would revolutionise our understanding of plant–fungal symbiosis, nutrient cycling, and microbial ecology. With large potential for sustainable agriculture, carbon sequestration, and biotechnology.