关键词: 荔枝, 果皮褐变, 漆酶, 基因, 克隆, 表达

Abstract: The relationship between postharvest browning and the expression oflaccase gene（LcLac）in litchi pericarp was discussed in this work. The LcLac was cloned from‘Feizixiao’by screening cDNA libraries and 3′-RACE. The full-length cDNA sequence of LcLac was 1 779 bp in length，contained a 26 bp 5′-UTR，a 52 bp 3′-UTR and a 1 701 bp open reading frame（ORF），which encoded a 566 amino acid polypeptide. The deduced amino acid sequence of LcLac had high identities with laccase protein from Acer pseudoplatanus. RT-PCR analysis revealed differences among the expression of LcLac，showing the highest and lowest levels，respectively，of transcripts in flower and pulp. During the early stage of postharvest storage，the browning index of pericarp increased along with the increasing expression of LcLac. Moreover，the expression of LcLac was higher in pericarp of Feizixiao（higher brown index）than Ziniangxi（lower brown index）. The expression of LcLac was decreased in severe browning pericarp during the middle and late stage of postharvest storage. The results suggested that the up-regulated expression of laccase gene in pericarp at early storage stage may contribute to the postharvest pericarp browning.

Key words: Litchi chinenesis, pericarp browning, laccase, gene, cloning, expression