Sunflower, transgenic

Human serum albumin was the first full-length human protein to be expressed in the leaves of a transgenic plant (both tobacco and potato leaves were shown to express the protein). This report was published in 1990 [18]. Four years earlier, Barta and colleagues had demonstrated the expression of human growth hormone in tobacco and sunflower callus, and the protein was expressed as a fusion with the Agrohacterium tumefaciens nopaline synthase enzyme [17]. 

Jerusalem artichoke has been the source of genetic material for the transformation of other crop species. Numerous transformations have been conducted with cultivated sunflower, and some with sunflower-Jerusalem artichoke hybrids, but no attempt to date has been made to improve Jerusalem artichoke as a crop via genetic transformation. However, Jerusalem artichoke is a classic tissue culture species (see Section 9.3), while much of the experience gained with transgenic sunflower is applicable to Jerusalem artichoke. Therefore, the means of transforming Jerusalem artichoke are largely in place. 

Breeding a mid-oleic sunflower requires at least one oleic parent. The USDA/ ARS Northern Crop Science Laboratory in Fargo, North Dakota, provided private companies with crossing lines of mid-oleic sunflower. Hybrid seeds were developed by traditional crossing methods no hybrids of transgenic sunflower were used. The mid-oleic concentration appears to be controlled by a partially dominant major gene and one or more dominant minor modifier genes (46, 47). 

Plants tolerant to imidazolinones have been produced by both transgenic and non-transgenic mechanisms. However, all of the imidazohnone-tolerant crops currently being sold have been developed by non-transgenic methods. The first imidazolinone-tolerant crop (maize) was introduced in 1992. Subsequently, four additional imidazolinone-tolerant crops (canola, rice, wheat and sunflower) have been commercialized [31]. All of the imidazohnone-tolerant crops are being sold under the CLEARFIELD trade name. 

DuPont scientists were the first to clone FAD2 and FADS genes from the soybean (2). They also provided conclusive evidence for the mechanism of polyunsaturated fatty acid biosynthesis, when antisense or cosuppression of the FAD2 gene led to lower n-6 desaturase activity, and the accumulation of oleic acid in glycerolipids. This was demonstrated not only in soybeans, but also in other oilseed crops, such as canola and sunflower (Table 1). These transgenic events... 

Snow, A.A., D. Pilson, L.H. Riesenberg, M.J. Paulsen, N. Pleskac, M.R. Reagon, D.E. Wolf, and S.M. Selbo. 2003. A Bt transgene reduces herbivory and enhances fecundity in wild sunflowers. Ecol. Appl. 13 279-286. 

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