Cloning and Real-time Expression Analysis of a Novel MAPK Kinase Gene BnMKK2 in Brassica napus

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 39.3k Da 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.