Abstract: An F2 population derived from a cross between lettuce PI491070（entire leaf）and PI536760（lobed leaf）was used to study the gene controlling leaf shape. The segregating ratio of lobed to non-lobed leaf showed that lobed leaf was controlled by a single dominant gene. Using the BSR-seq method，the gene controlling lobed leaf was mapped on Chr3，in the interval of 60–140 Mb. A large F2 population with 1 159 recessive individuals was used to fine map the causal gene to the interval of Chr3：116.24–118.15 Mb. Twenty-four genes were predicted in this region. One gene LG3316063 encoding a zinc finger protein，has one base pair difference，leading to amino acid change between two parents. Five genotypes with lobed leaves randomly chosen from lettuce germplasm all have “G”at this SNP，while 7 genotypes with non-lobed leaves have nucleotide “T”. Therefore，the gene LG3316063 is predicted to be the candidate gene controlling the lettuce lobed leaf.

Key words: Lactuca sativa, lobed leaf, BSR-seq, gene mapping