Selection of Castor for Divergent Concentrations of Ricin and Ricinus communis Agglutinin
- Scott D. Pinkerton,
- Rial Rolfe,
- Dick L. Auld ,
- Victor Ghetie and
- Brenda F. Lauterbach
Dep. of Plant and Soil Science, Texas Tech Univ., Lubbock, TX 79409-2122 Microbiology and Immunology, 5B191 Health Science Center Building, Texas Tech Univ./Health Sciences Center, Lubbock, TX 79409 Cancer Immunobiology Center and Dep. of Microbiology, U.T. Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75235-8576 Abstract
One of the most limiting factors in the production and processing of castor (Ricinus communis L.) is the presence of ricin and Ricinus communis agglutinin (RCA) in the endosperm. These highly toxic proteins create potential health hazards that have limited castor production in the USA, The objectives of this research were to develop a rapid assay to quantify ricin + RCA concentration in whole and partial seed of castor; to screen the USDA castor germplasm collection for ricin + RCA concentration; and to determine the inheritance of ricin + RCA in segregating populations of castor. A radial immunodiffusion (RID) assay based on ricin specific antibodies was shown to be highly repeatable in estimating the relative ricin + RCA concentrations of 18 castor accessions (rs = 0.98**). This assay could be used on whole seed or a small portion of the endosperm removed distal to the caruncle to maintain seed viability. The ricin + RCA concentration of 263 accessions from the USDA castor collections ranged from 1.9 to 16.0 mg g−1. Two accessions, PI 257 654 and PI 258 368, with low ricin + RCA concentrations were crossed with the commercial cultivar Hale. Three F3 seed from each F2 plant of six segregating populations were evaluated for ricin + RCA concentration. Individual plants of the six F2 populations and seed of the six F3 populations had an extremely wide range and significantly differed in ricin + RCA concentration. F3 plants with low and high levels of ricin + RCA were selected.
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