Herbicide-tolerant transgenic plants in high yielding commercial wheat cultivars obtained by microprojectile bombardment and selection on Basta

Most of the published work on transgenic wheat has used tissue culture responsive varieties such as 'Bobwhite'. The aim of the present study was to produce transgenic lines in modern high-yielding wheat cultivars irrespective of their tissue culture potential, using 'Biolistic' approach. Three of the highest yielding Indian wheat cultivars, namely CPAN 3004, Sonalika and UP 2338 were chosen for transformation. Stable transgenic plants with bar (conferring resistance to herbicide Basta) and gus genes were produced in each of these cultivars. Earlier developed transformation and regeneration protocols for tissue culture responsive lines were modified for obtaining transformation frequencies ranging from 0.14 to 0.83%. These frequencies are comparable with the published reports using the most responsive lines. Analysis of co-segregation patterns for bar and gus genes in the R1 progeny of a CPAN 3004 transformant indicated integration at two different sites in the genome. While both the sites have functional gus gene, only one of these has a functional bar gene, giving 15:1 and 3:1 segregation ratios for the two genes, respectively. Expression of bar gene under the maize ubiquitin promoter was high enough to provide protection against topical application of 250 mg/l gluphosinate ammonium, a concentration that killed most of the weeds including Phalaris minor.