Submitted to: Industrial Crops and Products
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/17/2010
Publication Date: 8/3/2011
Citation: Chen, G.Q., Lu, C., Lin, J.T. 2011. Hydroxy fatty acid synthesis and lipid gene expression during seed development in Lesquerella fendleri (L.). Industrial Crops and Products. doi:101.1016/j.indcrop.2010.08.03. Interpretive Summary: Lesquerella fendleri (L.) (Brassicaceae), being developed as a new industrial oilseed crop in the southwestern region of U.S., is valued for its unusual hydroxy fatty acid (HFA) in seed. One of the efforts has been focused on searching for targets that may up-regulate HFA synthesis in seed. However, knowledge of the regulatory mechanisms remains largely unknown. By using a established staging system, we describe the temporal changes in fatty acid composition, accompanying with profiles of gene expression. Our results not only reveal the initial timing of HFA accumulation but also provide information on promoter activity for each gene, which are critical to the understanding of regulatory mechanisms involved in the HFA synthesis and accumulation in L. fendleri.
Technical Abstract: Lesquerella fendleri is a developing oilseed crop in U.S. Its seed oil is rich in hydroxy fatty acid (HFA), lesquerolate (C20:1OH), suitable as a raw material for many industrial applications. To understand regulatory mechanism underlying synthesis and accumulation of the lesquerolate, we have investigated the changes in fatty acid composition and lipid gene expression in developing seed from 7 days after pollination (DAP) to desiccation (49 DAP). Accumulation of lesqurolate started at 21 DAP, increased quickly between 21 and 35 DAP and reached a plateau of 50-55% of total lipids at 35-49 DAP. We also detected other two types of HFA, ricinoleate (C18:1OH) and auricolate (C20:2OH), which accumulated at low levels during most stages of seed development but had different initiation time. Ricinoleate was detected as early as 14 DAP whereas auricolate began to accumulate at 21 DAP or later. Using real-time PCR, we quantified the transcript level of three lipid genes, LfFAH (bifuntional oleate 12-hydroxylase:desaturase), LfKCS3 (3-ketoacyl-CoA synthase) and LfFen1 (delta-12 desaturase), in seed at various developmental stages. Although all of these three genes displayed a bell-shaped pattern with a peak at 35 DAP and a sharp decline at 42-49 DAP, they had different starting background levels and maximum inductions. Since our results are based on a defined time course of seed development that allows us to compare the initial timing and temporal pattern of different biochemical and cellular activities. The relationship among gene expression, HFA accumulation and seed development are discussed.