关键词: 番茄, 漆酶, LAC, 克隆, 抗性

Abstract: Laccases are glycoproteins with polyphenol oxidase acitivity depending on copper. They ubiquitously exist in plants，fungi，insects，bacteria and other organisms，playing crucial roles in lignin synthesis，ion absorption and stress responses. It has been documented that several LAC genes were regulated by microRNAs at post–transcriptional level. In this study，homology BLAST was conducted in GenBank for LAC ESTs. Resultly，15 tomato ESTs highly similar with LAC genes were obtained，and spliced into a LAC fragment named as LeLACmiR397 containing a recognition site of miR397. In addition，a Cu-oxidase domain was predicted to be in the deduced LeLACmiR397 protein. To check the temporal and spatial expression of LeLACmiR397，semi-quantitative RT-PCR was performed. It was found that LeLACmiR397 specifically expressed in roots，flowers，ripe fruit and callus，but not in leaves. Then，its full length cDNA was cloned with RT-PCR and 5′- and 3′-RACEs，and registered as EU503151 in GenBank，corresponding to Solyc07g049460.2.1 in tomato genome. The data showed that LeLACmiR397 expression was down-regulated in the transgenic tomato overexpressing miR397a，and the contents of PPO，POD and SOD were reduced too. When being treated with Syringic acid and Sinapic acid，transgenic tomatoseedlings overexpressing LeLACmiR397 had longer root system and showed stronger resistance than WT. These results suggested that LeLACmiR397 was related to resistance to Syringic acid and Sinapic acid in tomato.

Key words: tomato, laccase, LAC, cloning, LeLACmiR397gene, resistance