ORIGINAL PAPER An effective method of sonication-assisted Agrobacterium-mediated transformation of chickpeas Malabika Roy Pathak Æ Riyad Yousif Hamzah Received: 27 June 2007 / Accepted: 25 January 2008 / Published online: 9 February 2008 Ó Springer Science+Business Media B.V. 2008 Abstract An efficient and reproducible transforma- tion method of sonication- assisted Agrobacterium- mediated transformation (SAAT) was developed for chickpea (Cicer arietinum L.). Agrobacterium tum- efaciens (LBA4404) harboring pCAMBIA1305.2 was used to transform decapitated embryo explants of two cultivars of chickpeas. By using a series of co-cultivation, callus induction, shoot initiation and root inducing media, a large number of transgenic plants were recovered. Transient expressions of GUS gene were detected by X-Gluc histochemical assay in transformed tissues. DNA analysis of T0 and T1 plants by PCR and Southern hybridization confirmed the integration of transgenes in initial and next generation transformants in different transgenic lines. The transformation efficiency was more than two times higher in SAAT treatment than simple Agro- bacterium without sonication. Keywords Agrobacterium tumefaciens Á Chickpeas Á SAAT Á Transformation Introduction Chickpea is an important, widely cultivated pulse crop and a good source of protein for human, as well as animal. It is the most common grain legume in about 40 countries of the world, including semi-arid region (Rao et al. 2002). Reports of successful introduction of commercially valuable genes in chickpea varieties are limited. There are several recent reports of transgenic chickpeas production aimed at developing a transformation system using Agrobacterium-mediated and biolistic transformation methods (Tewari-Singh et al. 2004; Senthil et al. 2004; Polowick et al. 2004) but the reported trans- formation efficiency is low. Therefore, more efficient method of transgenic chickpea production is required. Agrobacterium provides one of the main vehicles for introducing foreign DNA into legume plants. In order to enhance transformation rates, improvements have been made in the delivery system of the bacterium (Bidney et al. 1992; Santarem et al. 1998), vector construction (Hansen et al. 1994; Ishida et al. 1996), addition of thiol compounds during co-cultivation (Christou 1997; Olhoft et al. 2001) and culture methods of explants (Roy et al. 2000; Somers et al. 2003). Sonication has been used to enhance Agrobacterium-mediated transformation of many different plant species (Trick and Finer 1997; Santarem et al. 1998). SAAT consists of subjecting the target tissue to brief periods of ultrasound while immersed in an Agrobacterium suspension (Trick and M. R. Pathak (&) Á R. Y. Hamzah Biotechnology Program, Arabian Gulf University, P. O. Box 26671, Manama, Kingdom of Bahrain e-mail: malabikarp@agu.edu.bh 123 Plant Cell Tiss Organ Cult (2008) 93:65–71 DOI 10.1007/s11240-008-9344-6