Crispr-Cas9 mutagenesis of plum by expressing Spyo\Cas9UAS.Tag:NLS(Unk) under the control of Scer\GAL4GMR71G10 and using plumUAS.gRNAx2.pCFD6 as a guide (also expressed under the control of Scer\GAL4GMR71G10), results in a high frequency of mushroom body gamma neuron pruning defects.