Theor Appl Genet (1996) 93: 142-150 Springer-Verlag 1996 F. J. L. Aragfio L. M. G. Barros A. C. M. Brasileiro S. G. Ribeiro F. D. Smith J. C. Sanford J. C. Faria E. L. Rech Inheritance of foreign genes in transgenic bean (Phaseolus vulgaris L.) co-transformed via particle bombardment Received: 5 October 1995 / Accepted: 1 December 1995 Abstract Exploiting the biolistic process we have gener- ated stable transgenic bean (Phaseolus vulgaris L.) plants with unlinked and linked foreign genes. Co-transformation was conducted using plasmid constructions containing a fusion of the gus and neo genes, which were co-introduced with the methionine-rich 2S albumin gene isolated from the Brazil nut and the antisense sequence of AC1, AC2, AC3 and BC1 genes from the bean golden mosaic gemin- ivirus. The results revealed a co-transformation frequency ranging from 40% to 50% when using unlinked genes and 100% for linked genes. The introduced foreign genes were inherited in a Mendelian fashion in most of the transgenic bean lines. PCR and Southern blot hybridization confirmed the integration of the foreign genes in the plant genome. Key words Transgenic bean Phaseolus vulgaris Co-transformation Biolistic Inheritance Introduction Common bean (Phaseolus vulgaris L.) is the most impor- tant food legume in the developing world. In Latin Amer- ica, beans are a very important source of protein and calories. Despite its nutritional importance, production growth rates have been declining in Brazil and Andean re- gions. The main reasons for this are diseases, insects, nu- Communicated by M. Koorneef F. J. L. Aragfio ([]) L. M. G. Barros - A. C. M. Brasileiro S. G. Ribeiro - E. L. Rech Centro Nacional de Pesquisa de Recursos Gen6ticos e Biotecnologia, EMBRAPA, RO. Box 02372, Brasflia, DF, 70849-970, Brazil F. D. Smith. J. C. Sanford Department of Horticultural Sciences, New York State Agricultural Experiment Station, Cornell University, Geneva, NY 14456, USA J. C. Faria Centro Nacional de Pesquisa de Arroz e Feij~o, EMBRAPA, RO. Box 179, Goigmia,GO, 74001, Brazil tritional deficiencies, and a lack of drought tolerance. Con- sequently, there is considerable interest in the introduction of agronomically useful traits into beans by breeding and genetic engineering. Early efforts to produce transgenic bean plants failed due to poor DNA delivery and regeneration systems. While McClean et al. (1991) were able to introduce genes into beans using the Agrobacterium system, they were unable to regenerate transgenic plants. Several protocols have been described for shoot organogenesis from apical or axillary meristems in beans (McClean and Grafton 1989; Malik and Saxena 1992; Mohamed et al. 1992). Recently, Russel et al. (1993) utilized these information to achieve transgenic bean plants, using an electrical-discharge par- ticle acceleration device. Over the last decade, several investigators have utilized the co-transformation process to introduce unlinked and linked genes into plants, mainly by the electroporation of protoplasts (Schocher et al. 1986; Tagu et al. 1988; Datum et al. 1989; Christou and Swain 1990; Herv6 et al. 1993). Co-transformation frequencies varied from 18% to 88% for unlinked genes, versus 50% to 100% for linked genes (Klein et al. 1989; Christou and Swain 1990). Using the biolistic process, Spencer et al. (1990) observed a co-trans- formation frequency of 50% in maize cells with two sep- arate plasmids, while Gordon-Kamm et al. (1990) found a co-transformation frequency ranging from 68% to 86% in a transformed cell suspension of maize. To date, the effi- ciencies of co-transformation in plants achieved by the ap- ical cells particle bombardment system have not been eval- uated. Studies analyzing the progeny of transgenic plants, such as soybean (Hinchee et al. 1988; Christou et al. 1989), to- bacco (Uchimiya et al. 1986), Arabidopsis (Datum et al. 1989), rape (Herv6 et al. 1993) and cotton (McCabe and Martinell 1993), transformed by distinct transformation systems have shown that the transgenes are inherited as Mendelian genes. This has been interpreted as being sin- gle locus integration. Nevertheless, in some cases a non- Mendelian inheritance has been observed, with segrega- tion ratios of more than three transformed plants for one