Refined glufosinate selection and its extent of exposure for improving the Agrobacterium-mediated transformation in Indian soybean (Glycine max) genotype JS-335.

Abstract

Soybean like many other crops, in this genomic era, has well-established genomic database which provides a wide range of opportunities for improvement through genetic manipulation. But the growing demand for soybean transgenics with increased production and improved quality has been handicapped due to inefficient transformation strategies and hence an efficient, stable and reliable transformation system is of prime requisite. In the present study, Agrobacterium-mediated transformation was standardized by refining the glufosinate selection system in terms of dosage (0-6 mg l-1) and degree of exposure. The cotyledonary node explants (with and without wounding) initially cultured on a non-selective shoot induction medium for 10 days before transferring them to the selective SIM with an optimized concentration of 5.0 mg l-1 ammonium glufosinate, showed least selection escape frequency. Wounded cotyledonary node explants infected with Agrobacterium tumefaciens harboring pBIN-bar construct, showed an improved regeneration efficiency of 55.10% and transformation efficiency of 12.6% using Southern blotting in T1 plants. Southern analysis of T1 plants confirmed the integration of bar gene into the genomic DNA and the bar positive T1 plants segregated in 3 : 1 ratio. This is the first report, to our knowledge, of a high transformation efficiency using Agrobacterium-mediated cot node-glufosinate system in an Indian soybean genotype.