An organogenic plant regeneration system for common bean (Phaseolus vulgaris L.) P. Delgado-Sa ´nchez a , M. Saucedo-Ruiz b , S.H. Guzma ´n-Maldonado a , E. Villordo-Pineda a , M. Gonza ´lez-Chavira a , S. Fraire-VelA ´ zquez b , J.A. Acosta-Gallegos a , A. Mora-Avile ´s a, * a Instituto Nacional de Investigaciones Forestales, Agrı ´colas y Pecuarias, Campo Experimental Bajı ´o, Regio ´n Centro, Unidad de Biotecnologı ´a, Km. 6.5 Carr. Celaya-San Miguel de Allende, C.P. 38010 Apdo, Postal 112, Celaya, Guanajuato, Mexico b Universidad Auto ´noma de Zacatecas, Departamento de Biologı ´a Molecular de Plantas, Blvd. Revolucio ´n Mexicana. Zacatecas, Zacatecas, Mexico Received 25 November 2005; accepted 27 November 2005 Available online 27 December 2005 Abstract An organogenic regeneration protocol in common bean (Phaseolus vulgaris L.) using embryo-axes derived from mature seeds from commercial cultivars Flor de Junio Marcela (FJM) and Flor de Mayo Anita (FMA) is reported. Embryonic axes were excised from surface sterilized seeds and established in MS medium containing different benzylaminopurine (BAP) and adenine (A) concentrations. Efficient regeneration was achieved when 5 or 10 mg/l BAP was added to the medium regardless of the A concentration, inducing the formation of differentiated cells as bud clusters. These clusters mainly formed at the internodal segment of the embryo for FJM and at the apical segment for FMA embryonic axes. Regeneration efficiency varied considerably between the two cultivars where FJM showed higher bud cluster formation (90%) and full plant regeneration (83%), whereas FMA showed 18% bud cluster formation, and 50% full plant regeneration. The division and transfer of FMA and FJM bud clusters to induction media every 15 days resulted in the formation of three to five new bud clusters each transfer. A single 5 mm cluster formed up to 15 shoots from which 1–2 plants were regenerated. Genetic variation analysis by amplified fragment length polymorphism (AFLP) showed no variation between regenerated plants. # 2005 Elsevier Ireland Ltd. All rights reserved. Keywords: Phaseolus vulgaris L.; Organogenesis; Benzylaminopurine; Adenine; Shoot formation; Genetic variation 1. Introduction Common bean (Phaseolus vulgaris L.) is the most important food legume for people in Latin America and Africa. In these areas, animal protein is limited and bean consumption satisfies most of the protein requirements. Furthermore, common bean accounts for 22% of the total protein consumed by humans in the world [1–3]. Undesirable characteristics in common bean, such as susceptibility to drought, pests and diseases, as well as low nutritional quality [4], represent a challenge for plant breeders using conventional breeding methods. Currently, several genetic engineering techniques are employed in common bean breeding, however, plant regeneration using published methods has not been easily reproducible [5–16]. Specific examples of reports of common bean regeneration methods are in vitro regeneration by somatic embryogenesis [5,6,17,18] and organogenesis [8–11,15,16,19,20]. In addition, regeneration methods successfully used with P. acutifolius, P. coccineus and P. polyanthus, produced erratic results when applied to the regeneration of P. vulgaris, resulting in shoot production instead of complete plants [12,16,19]. The need for a protocol that results in efficient differentia- tion, shoot development and whole plant regeneration is an essential requirement for genetic transformation in plants. Homologous, heterologous or homoeologous gene transfer is becoming a common approach in genetic improvement programs. This process, together with traditional plant breeding methods, could accelerate the development of new cultivars www.elsevier.com/locate/plantsci Plant Science 170 (2006) 822–827 * Corresponding author. Tel.: +52 461 6115323x186; fax: +52 461 6115323x181. E-mail address: mora.alejandra@inifap.gob.mx (A. Mora-Avile ´s). 0168-9452/$ – see front matter # 2005 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.plantsci.2005.11.015