Scientists developed a new method to genetically modify a beneficial fungus called Penicillium sclerotiorum by removing its cell wall and introducing new genes. They added a glowing green marker (GFP) to track the fungus as it colonizes tomato plant roots. The study shows that enzymatic treatment of seeds significantly improves how well the fungus attaches to roots, potentially helping plants grow better while revealing how the genetic modification affects the fungus’s internal chemistry.