Herbicide-resistant transgenics of bread wheat (T-aestivum) and emmer wheat (T-dicoccum) by particle bombardment and Agrobacterium-mediated approaches

Hexaploid bread wheat (Triticum aestivum) and tetraploid emmer wheat (T. dicoccum) hold immense agricultural and economical importance as their end products have varied utilities depending upon the visco-elasticity and other properties of the flour. In the present study, highly regenerable basal segment calli have been employed as the target tissue for genetic transformation of Indian varieties of bread wheat (CPAN1676, PBW343) and emmer wheat (DDK1001). The bar gene conferring herbicide resistance was introduced in one-month-old calli employing both particle bombardment and Agrobacterium-mediated transformation strategies. Transgenic calli were selected on phosphinothricin-containing regeneration medium and putative transformants were raised to maturity. Though the plants exhibited reduced vigour in terms of height and tillering, nonetheless, seed set was normal. The presence of the transgene (bar) was confirmed by PCR and Southern hybridization. In general, the transformation efficiency was found better with Agrobacterium, even though the construct carried CaMV35S driven bar gene, whereas in the case of biolistics Ubi1 (a monocot promoter)-driven bar gene was employed. Transformation efficiency in the range of 4% was obtained with particle bombardment, whereas it was 7.5% using Agrobacterium-mediated co-cultivation. The different varieties of bread and emmer wheat investigated did not show any marked difference in their transformation ability and could be attributed to a well-established regeneration system in these varieties.