Sonication-assisted efficient Agrobacterium-mediated genetic transformation of the multipurpose woody desert shrub Leptadenia pyrotechnica

The desert shrub Leptadenia pyrotechnica (Forssk.) Decne (Asclepiadaceae) is an important multipurpose woody species of tropical and sub-tropical arid regions. The shrub's excellent pharmacological properties, importance in desert afforestation and role in sand dune fixation has been elaborately studied in recent years which make it a potential candidate for genetic manipulation in the global warming scenario. We have developed an Agrobacterium-mediated transformation protocol for L. pyrotechnica using hypocotyl explants from 5 days old seedlings. The reliability of the protocol has been tested by transforming the species with gus and gfp reporter genes separately. Hypocotyl explants were sonicated for 40 s, infected with Agrobacterium suspension of OD600 0.5, co-cultivated in the dark for 2 days at 26 A degrees C in presence of 200 mu M acetosyringone. Transgenic plants were obtained after 20-22 weeks at a frequency of 14 and 11 % for gus and gfp reporter genes respectively. Transgenic plants were confirmed by PCR and Southern blots. Expression of the two reporter genes has been tested in different stages of transgenic plant development. No phenotypic differences between the wild-type and transgenic plants were noted. This method will be very helpful to introduce alien genes-of-interest for various biotechnological applications.