Previous studies have shown that ABL1 may play an important role in the process of plant leaf growth and development,rosette leaves of the mutant abl1 formed later than wild-type and the mature leaves were smaller and serrate in abl1.In this study,using the Map-based cloning strategy,ABL1 gene was first positioning in the bottom region of the chromosome I by the primary mapping,and go a step further,ABL1 gene was limited in to the chromosomal region between two molecular markers T23K8 and T8F5,which contains 44 genes.A mutation in genes FAS1 was responsible for the mutant phenotype by bioinformatics analysis.FAS1 encode a subunit of the chromatin assembly factor CAF1,which regulate the apical meristem of the plant.RT-PCR results have indicated that the expression of ABL1 gene is completely knocked out and complementation experiments confirmed that abl1 is indeed a new allelic mutation in gene FAS1.Based on the study above,ABL1 may play a crucial role in the plant leaf morphogenesis.