This research examined the genetic makeup of a mold called Penicillium paneum that contaminates pears and apples by producing a toxic substance called patulin. Scientists sequenced the entire genome and identified all the genes responsible for patulin production. They found that this mold has 33 different gene clusters for producing various toxic compounds, with the patulin-producing genes being highly similar to those in other related molds. This genetic knowledge could help develop better strategies to prevent patulin contamination in fruit crops.