Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: August 21, 2009
Publication Date: November 14, 2009
Citation: Chen, G.Q. 2009. Engineering Lesquerella for Safe Castor Oil Production. The Association for the Advancement of Industrial Crops (AAIC) 21st Annual Meeting in Termas de Chillan, Chillan, Chile, November 14-19th, 2009. Interpretive Summary: Castor oil is the conventional source of ricinoleate (C18:1OH). Ricinoleate and its derivatives are used as raw material for numerous industrial products, such as lubricants, plasticizers and bio-diesel. The production of castor oil however, is hampered by the presence of the toxin ricin and hyper-allergic 2S albumins in castor seed. 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). The HFA in L. fendleri was named lesquerolic acid (C20:1OH), which is derived by a 2 carbon elongation of ricinoleate. By suppressing the elongation step in L. fendleri through genetic engineering, it is possible to generate a L. fendleri crop producing ricinoleate.
Technical Abstract: As a part of genetic approach to engineering ricinoleate synthesis, we investigated the seed development in L. fendleri. The morphological, physiological and biochemical changes during seed development of Lesquerella fendleri were characterized from 7 days after pollination (DAP) to desiccation. The entire course of seed development lasted about 49 days and it can be divided to seven sequential stages (I to VII). During the early stages (I to III, 7 to 21 DAP), seed grew rapidly, showing dramatic increase in size and fresh weight. During mid-maturation stages (IV to V, 28 to 35 DAP), storage lipids, proteins and other components of dry weights accumulated at maximum rates. The accumulation curves followed a sigmoidal pattern during seed development. When seed progressed to late-maturation/desiccation stages (VI to VII, 42 to 49 DAP), the size of the seed decreased slightly and the color changed from green to orange-brown. Seed proteins were also analyzed using SDS-PAGE. Proteins with high molecular weights were prominent in developing seed at early stages (I to III). At stage IV (28 DAP), proteins with low molecular weight appeared while the high molecular weight proteins decreased in proportion. These low molecular weight proteins became predominant throughout the remaining stages of seed development. Forty-seven percent of freshly harvested seed at 35 DAP were able to germinate after 7 days incubation. The germination percentage increased to a maximum of 95% at 42 DAP. These results provide integrative information for understanding the seed development in L. fendleri, which is critical to the development and implementation of a genetic approach for crop improvement. To genetically modify L. fendleri, we have successfully developed a protocol to transform L. fendleri. We have demonstrated a GUS reporter gene that was incorporated into the genome and inhered to the next generation of transgenic L. fendleri. The transformation protocol provides means not only to engineer a ricinoleate-producing L fendleri for safe castor oil production, but also to improve L fendleri as a superior crop with high yield and disease-resistance.