Submitted to: Meeting Abstract
Publication Type: Abstract only
Publication Acceptance Date: 7/15/2008
Publication Date: 9/7/2008
Citation: Chen, G.Q. 2008. Biotechnology For hydroxy Fatty Acid Production in Oilseed. 20th Annual Meeting of the Association ofr the Advancement of Industrial Crops (AAIC), College Station, TX, September 7 to 11, 2008. Interpretive Summary: Castor is an important oilseed crop with numerous industrial uses. However, the production of castor oil is hampered by the presence of the toxin ricin and hyper-allergenic 2S albumins in its seed. We are developing a safe source of castor oil by two approaches: blocking gene expression of the ricin and 2S albumins in castor seed; and engineering a temperate oilseed crop, Lesquerellar fendelri, to produce castor oil.
Technical Abstract: Conventional source of hydroxyl fatty acid is from castor oil which contains 90% ricinoleate. Ricinoleate and its derivatives are used as raw materials for numerous industrial products, such as lubricants, plasticizers and bio-diesel. However, the production of castor oil is hampered by the presence of the toxin ricin and hyper-allergenic 2S albumins in its seed. We are developing a safe source of castor oil by two approaches: blocking gene expression of the ricin and 2S albumins in castor seed and engineering Lesquerella fendleri to produce ricinoleate. L. fendleri is a new oilseed crop whose seed contains lesquerolic acid derived from a 2 carbon elongation of ricinoleate. By suppressing the elongation step in L. fendelri through genetic engineering, it is possible to generate a L. fendleri crop producing ricinoleate. We conducted a series of seed development studies in castor and L. fendelri, including seed morphogenesis, oil and storage protein accumulation and lipid gene expression. In castor, the entire course of seed development can be divided into eight stages and each satge can be distinguished by seed coat color and volume of cellular endosperm. Synthesis of ricin, 2S albumin and ricinoleate/oil occurred during cellular endosperm development. Concomitantly, we observed increased transcript levels of 12 lipid genes involved in synthesis of ricinoleate/oil, but with various temporal patterns and different maximal induction ranging from 4- to 43,000-fold. These results indicate that gene transcription exerts a primary control in ricinloeate/oil biosyntheses, and there are different transcriptional regulatory mechanisms involved in the gene expression. Little is known about the seed development in L. fendelri, we describe here the morphological and physiological changes of developing seeds from fertilization to desiccation. The whole period of seed development is divided to seven continuous stages covering about 49 days. Morphology, fresh and dry weight of the whole seed were documented at each stage. Oil and total protein content were also measured. Profiles of the total proteins were further examined for seed at each stage. Moreover, we quantified the transcript levels of key genes involved in lesquerolic acid synthesis. We found that the seven-stage time course allows for revealing various temporal patterns of seed development in L. fendelri and provides a basis for accurate comparisons among experiments. The relationships among morphological and physiological changes, oil and protein accumulation, and gene expression are discussed. To genetically modify L. fendelri, we tested the transformation efficiency of leaf, root and stem tissues of L. fendelri using Agrobacterium-mediated transformation technology. We found that root tissue has the highest efficiency in adventitious shoot formation, while the stem has the least. As leaf is the most abundant tissue, we used leaf and demonstrated stable transformation in L. fendelri. The transformation technology for L. fendelri can be used not only to create a ricinoleate-producing crop, but also to improve L. fendelri as a superior crop with high yield and disease-resistance in general