Abstract: The full-length cDNA of Hsp70 in Lactuca sativa L. was cloned using reverse transcription polymerase chain reaction（RT-PCR）and rapid-amplification of cDNA ends（RACE）. The results showed that LsHsp70 open reading frame is 2 094 bp which encoding a polypeptide of 697 amino acids with an estimated molecular mass of 74.1 kD. The three highly conserved HSP70 family signatures is IDLGTTNS，VFDLGGGTFDVSVL and VILVGGSTRIPAV. The similarity of amino acids between Hsp70 with the homologous gene in Arabidopsis thaliana is 92%. The expression patterns were analyzed by Real-time quantitative PCR in heat-resistant type‘Z36’and heat-sensitive type ‘S106’ under different high temperatures. The results showed that the high temperature could promote LsHsp70 expression，and LsHsp70 expression responses under 37 ℃ were more sensitive and had a large accumulation than under 42 ℃；In the same temperature，‘Z36’responses speed were more slowly and last longer.

Key words: Lactuca sativa L., LsHsp70, cloning, gene express, high temperature stress, heat resistance