Characterization of a Desiccation Stress Induced Li pase Gene from Brassica napus L.

Abstract

Lipases are known to have important functions in ma ny physiological processes in plants. Here, we cloned a lipase gene via Rapid Amp lification of cDNA Ends (RACE) technique from Brassica napus L., designated as BnDIL1 ( B. napus Desiccation- Induced Lipase 1). The lipase enzyme activity was c onfirmed 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, maturat ion, dormancy, pregermination and germination. The transcription l evel of lipid degradation pathway was enhanced during the processes of seed maturatio n, dormancy, pregermination and germination, and was higher in seeds of low oil-con tents line than that of high oil-contents line. However, BnDIL1 was significantly activated when seed desiccation started. Both “slow desiccation” and “fast desiccation” treatment s on seedlings dramatically activated the transcription of BnDIL1 , while only “slow desiccation” stress, which would induce the cell apoptosis, significantly activated the transcr iption of lipid degradation gene. This result demonstrated that BnDIL1 in B. napus was desiccation stress dependent gene rather than fatty acids degradation gene. Keywords: Enzyme activity, Oil-content, Rapid amplification, Seed, Transcripti on profiles of BnDIL1.