Characterization of a desiccation stress induced lipase gene from Brassica napus L.

Lipases are known to have important functions in many physiological processes in plants. Here, we cloned a lipase gene via Rapid Amplification of cDNA Ends (RACE) technique from Brassica napus L., designated as BnDIL1 (B. napus Desiccation-Induced Lipase 1). The lipase enzyme activity was confirmed by estimating the lipase activity and reduced lipids content in Saccharomyces cerevisiae (pep4) transformant. Two B. napus lines with different oil contents were employed to examine the transcription profiles of BnDIL1 during the processes of seed morphogenesis, maturation, dormancy, pregermination and germination. The transcription level of lipid degradation pathway was enhanced during the processes of seed maturation, dormancy, pregermination and germination, and was higher in seeds of low oil-contents line than that of high oil-contents line. However, BnDIL1 was significantly activated when seed desiccation started. Both “slow desiccation” and “fast desiccation” treatments on seedlings dramatically activated the transcription of BnDIL1, while only “slow desiccation” stress, which would induce the cell apoptosis, significantly activated the transcription of lipid degradation gene. This result demonstrated that BnDIL1 in B. napus was desiccation stress dependent gene rather than fatty acids degradation gene.