Somaclonal variation in the progeny of transgenic barley.

Somaclonal variation (SCV) in transgenic plants may slow the incorporation of introduced genes into commercially competitive cultivars. Somaclonal variation in transgenic barley (Hordeum vulgare L.) was assessed in one experiment by comparing the agronomic characteristics of 44 segregating transgenic lines in the T2 generation to their non-transformed parent ('Golden Promise'). A second experiment examined the agronomic characteristics of seven transgenic-derived, null (non-transgenic) segregant lines in the T2 and T4 generations. Compared to their uncultured parent, Golden Promise, most of these lines were shorter, lower yielding, and had smaller seed, and the variability among individual plants was higher. The frequency and severity of the observed SCV was unexpectedly high, and the transformation procedure appeared to induce greater SCV than tissue culture in the absence of transformation. Attempts to understand the sources of SCV, and to modify transformation procedures to reduce the generation of SCV, should be made.