Molecular cloning and characterization of a chitinase gene up-regulated in longan buds during flowering reversion

Abstract

A cDNA-amplified fragment length polymorphism (cDNA-AFLP) technique was used for differential screening of genes expressed in longan (Dimocarpus longan Lour.) flower buds undergoing normal development versus flowering reversion. One cDNA fragment up-regulated during flowering reversion was further cloned by rapid amplification of cDNA ends (RACE) technology. This cDNA consists of 961 nucleotides and encodes an open reading frame (ORF) of 227-amino acid residues. The nucleotides and deduced amino acid sequence were both identical against published chitinases from other species and hence this cDNA was designated as DLchi (GenBank accession No. GU177464). It has a signal peptide and glycoside hydrolase’s domain. The estimated molecular weight was 24.77 kD and the isoelectric point was 5.17. This protein might be grouped as a new member of class II chitinase based on the sequences available and hypothesis discussed. DLchi might be involved in the flower bud abscission observed in longan flowering reversion.

Key words: Longan, flowering reversion, chitinase gene, cloning, sequence analysis.