Aberrant degeneration of panicle (ADP) usually occurs during the reproductive growth in rice. It causes yield loss due to the reductions of panicle length, branch number, grain number per panicle and seed setting. However, the ADP phenotype is sensitive to growth environments and regulated by multiple quantitative trait loci, which have complicated the identification of ADP-related function genes.The molecular mechanism underlying ADP occurrence remain largely unknown. The tutou4 is a panicle degeneration mutant derived from a tissue culture, and shows abnormal panicle, reduction of panicle grain number and branch number, as well as single plant yield. Genetic analysis showed that the ADP trait was controlled by a pair of recessive nuclear gene. The candidate gene was finally mapped to the short arm of chromosome 8, flanked by both Indel markers Os8-3-2 and Os8-3-3, with an interval of 39.09 kb, which contained three encoding genes. The sequencing result showed a 4325-bp deletion in the promoter region and one base alternation (A?G, synonymous) of the gene LOC_Os08g06480, which was designated as OsLIS-L1/OsREL2/ASP1. Real-time PCR analysis revealed a reduction on gene expression in mutant to that of the wild type. Considering the expression level decreased in the tutou4, the mutant will be useful germplasm in the study of abnormal panicle degeneration.