Isolation and characterization of a BURP domain-containing gene BnBDC1 from Brassica napus involved in abiotic and biotic stress

A new gene encoding BURP domain-containing protein was isolated from oilseed rape (Brassica napus) following drought treatment. The cloned gene, designated as BnBDC1 (GenBank accession number AY293830 ), contains four major domains: an N-terminal hydrophobic domain, a short conserved segment, a characteristic repeated region and a C-terminal BURP domain. BnBDC1 is highly homologous to the dehydration-responsive RD22 gene from Arabidopsis thaliana, and belongs to the same gene family as BNM2 from B. napus. Northern blot and semi-quantitative reverse transcription polymerase chain reaction (RT-PCR) analyses show that BnBDC1 is constitutively expressed in rape shoots, but is not detectable in the roots, indicating that the expression of BnBDC1 is tissue specific. The expression level of BnBDC1 transcript is upregulated by mannitol, NaCl and abscisic acid (ABA), downregulated by UV irradiation and salicylic acid, and unresponsive to H2O2 and cold treatment. The accumulation of BnBDC1 transcripts generally increases within 2 h after initiation of the promoting stimulus. These results suggest that BnBDC1 has similar functions to those of RD22 of Arabidopsis, and may play an important role in response to osmotic stress and/or plant pathogen infection in B. napus.