White wood ear fungus (Tremella fuciformis) is a popular medicinal mushroom that cannot grow on its own in nature. Researchers studied how it interacts with a companion fungus and discovered that a specific gene called Tfsdh1 is crucial for the mushroom to use sorbitol sugar and grow properly. By using advanced genetic tools to remove this gene, they showed it’s essential for the relationship between the two fungi, offering insights into how to better cultivate this nutritious mushroom.