Cloning, Characterization and Expression of a Phenylalanine Ammonialyase Gene (M-PAL) from Plantain (Musa ABB cv. Dongguandajiao)

Abstract:

A full-length cDNA encoding PAL was cloned from leaves of plantain (Musa ABB cv. Dongguandajiao) by RT-PCR and RACE. The cDNA was 1300 bp in length and contained a complete ORF of 1191 bp which encodes a protein of 397 amino acid residues. Its deduced amino acid sequence had 89% identity with rice PAL and then this gene was hence designated as M-PAL. Southern hybridization analysis demonstrated that a small family of four to five PAL genes exists in plantain banana. The complete coding sequence of M-PAL was cloned into an expression vector pET32 (a+) and a protein about 43KD expressed in Escherichia coli BL21 (DE3) was the same as deduced molecular weight and showed phenylalanine ammonia-lyase activity. The transcript of M-PAL gene in the leaves was increased when the plantlets of plantain were inoculated with Fusarium oxysporum f.sp. cubense, indicating that the expression of M-PAL may be related to resistance of banana Fusarium wilt.

Key words:Plantain banana (Musa ABB cv. Dongguandajiao); Phenylalanine Ammonialyase; Fusarium wilt