Abstract: A new MAPKK cDNA BnMKK2 was isolated from Brassica napus Longyou 6. The cloned full-length cDNA was 1 344 bp, contained a 5′ untranslated region (5′UTR) of 111 bp, a 3′ untranslated region (3′UTR) of 165 bp, and a 1 068 bp ORF. BnMKK2 encoded a protein of 355 amino acids with a deduced molecular weight of about 39.3 kDa and with a PI of 6.8. The BnMKK2 exhibited closest homology to the Arabidopsis thaliana AtMKK2, so it was named BnMKK2(GenBank accession: HQ848661). Sequence Analysis indicated that the BnMKK2 protein exhibited closest homology to MAPKK, which is responsed to cold stress, and BnMKK2 played an important role in defending cold stress. Analysis by real-time RT-PCR indicated that the expression of BnMKK2 was increased in response to cold stress.

Key words: Longyou 6, Gene cloning, BnMKK2 gene, expression analysis