Abstract:

In this study, the only lycopene β-cyclase was cloned from Chinese cabbage (BrLCYB) and had 1 482 bp coding sequence. BrLCYB contains the only one intron in its gene sequence, corresponding to 5' UTR. The intron resulted in BrLCYB producing two types of transcripts (BrLCYB-1 and BrLCYB-2) after transcription. BrLCYB-1 accounted for 98.26% of the total BrLCYB transcripts. BrLCYB was widely expressed in a variety of organs and the whole embryonic development stage, and has a higher expression in flowers and mature embryos. The phylogenetic tree of LCYBs showed that the LCYBs of higher plants originated from cyanobacteria. During the evolution of LCYB genes, intron gain and intron loss, occurred successively in LCYBs, and finally no intron existed in coding sequences of LCYBs in higher plants. BrLCYB contained a lycopene β-cyclase domain. In order to further verify the function of BrLCYB, the pET-BrLCYB prokaryotic expression vector was constructed. The co-transformation of pACCRT-EIB and pET-BrLCYB into E. coli can make E. coli enriching orange-yellow β-carotene, proving that BrLCYB of Chinese cabbage had the function of lycopene β-cyclase.

Key words: Chinese cabbage, lycopene β-cyclase, gene, functional analysis