A development mutant ku7fy1 was obtained in mutant screening in Arabidopsis thaliana.It has a phenotype of narrow leaf and stunted growth.In this study,using the map-based cloning strategy and candidate gene sequencing we identified a point mutation in the WBC11(white-brown complex11) gene of ku7fy1.cDNA sequencing result of the mutant indicated that the mutation resulted in the detention of the 7th intron in the mature mRNA,which not only caused degradation of the mRNA but also led to premature translational termination.Toluidine blue staining suggested that its leaf cuticular had a defect.Genetic complementation experiment further confirmed that the mutant gene was WBC11.