Cloning and Sequence Analysis of Expansin Genes in Lit chi chinensis Sonn. Fruits

Using PCR degenerate primers designed with reference t o the conserved amino acid sequences of known expansins to amplify cDNA fragment s in litchi fruits by RT-PCR, two different cDNA fragments, named Lc-Exp1 and Lc-Exp2, were c loned. Lc-Exp1 and Lc-Exp2 was respectively composed of 531 bp and 537 bp, encoding 177 and 17 9 amino acids, respectively. Eight cysteine residues and 3 tryptophan residues, which are supposed to be the characteristics of expansins, are conserved in both Lc-Exp1 and Lc-Exp2. In addition, the homology between two expansins is 71.6% at nucleot ide acid sequence level and 76.3% at amino acid sequence level. The homology be tween Lc-Exp1 and Fa-Exp2 and Pp-Exp1 is 92.7% and 92.1%, b ut that of Lc-Exp2 and Fa-Exp2 and Pp-Exp1 is only 77.4% and 76.3% at amino acid sequence level, respectively.