T_L -DNA transformation decreases ABA level

The endogenous levels of ABA were measured in Agrobacterium rhizogenes A₄ T_l -DNA transformed oilseed rape (Brassica napus L. var. oleifera cv. Brutor and cv. Drakkar), cabbage (Brassica oleracea). A₄ transformed tobacco (Nicotiana tabacum cv. Xanthi) and their normal counterparts, using high performance liquid chromatography and enzyme-liked immunosorbent assay. Measurements were made on different plant tissues (i. e. floral stem, terminal bud, young leaf, mature leaf, root and root tips) and ABA levels were compared in unstressed and osmotically stressed oilseed rape plants (cv. Brutor). In unstressed Plants. in each of the 5 independent transformation events studied, a significant reduction (about 65% of control) in ABA concentration was observed in all transformed plants. When subjected to an osmotic stress, T_L transformed Brutor plants showed a higher ABA accumulation than untransformed plants. The change in ABA content as a consequence of T_L -DNA transformation is discussed with regard to phenotype, drought resistance and adaptability.