www.elsevier.de/jplph SHORT COMMUNICATION Mutant acetolactate synthase gene is an efficient in vitro selectable marker for the genetic transformation of Brassica juncea (oilseed mustard) Krishna Ray a , Arun Jagannath b , Suveena Arora Gangwani a,1 , Pradeep Kumar Burma a , Deepak Pental a,b, * a Department of Genetics, University of Delhi South Campus, Benito Juarez Road, New Delhi 110021, India b Centre for Genetic Manipulation of Crop Plants (CGMCP), University of Delhi South Campus, Benito Juarez Road, New Delhi 110021, India Received 7 November 2003; accepted 17 February 2004 Summary We report in this study, the successful deployment of a double mutant acetolactate synthase gene (ALS dm , containing Pro 197 to Ser and Ser 653 to Asn substitutions) as an efficient in vitro selection marker for the development of transgenic plants in Brassica juncea (oilseed mustard). The ALS enzyme is inhibited by two categories of herbicides, sulfonylureas (e.g. chlorsulfuron) and imidazolinones (e.g. imazethapyr), while the mutant forms are resistant to the same. Three different selection agents (kanamycin, chlorsulfuron and imazethapyr) were tested for in vitro selection efficiency in two B. juncea cultivars, RLM198 and Varuna. For both the cultivars, higher transformation frequencies were obtained using chlorsulfuron (3.8 70.6% and 4.6 70.9% for RLM198 and Varuna, respectively) and imazethapyr (10.2 70.7% for RLM198 and 7.8 7 1.2% for Varuna) as compared to that obtained on kanamycin (3.1 7 0.2% and 2.8 7 0.5% for RLM198 and Varuna, respectively). Additionally, transformation frequencies were higher on imazethapyr than on chlorsulfuron for both the cultivars indicating that imidazolinones are better selective agents than sulfonylureas for the selection of mustard transgenics. & 2004 Elsevier GmbH. All rights reserved. ARTICLE IN PRESS KEYWORDS Acetolactate synthase; Brassica juncea; Genetic transformation; In vitro selection marker Abbreviations: ALS dm , double mutant (dm) acetolactate synthase gene with Pro 197 to Ser and Ser 653 to Asn mutations; CTAB, cetyltriethyl ammonium bromide; IBA, indole-3-butyric acid; Pr, promoter *Corresponding author. Department of Genetics, University of Delhi South Campus, Benito Juarez Road, New Delhi–110021, India. Tel.: 91-11-24675203; fax: 91-11-26885270. E-mail address: dpental@hotmail.com (D. Pental). 1 Present Address: Bhatnagar International School, Vasant Kunj, New Delhi 110070, India. 0176-1617/$ - see front matter & 2004 Elsevier GmbH. All rights reserved. doi:10.1016/j.jplph.2004.02.001 Journal of Plant Physiology 161 (2004) 1079–1083