SOMACLONAL VARIATION IN THE PROGENY OF TRANSGENIC BARLEY

Somaclonal variation (SCV) in transgenic plants may slow the incorpora tion of introduced genes into commercially competitive cultivars. Soma clonal variation in transgenic barley (Hordeum vulgare L.) was assesse d in one experiment by comparing the agronomic characteristics of 44 s egregating transgenic lines in the T-2 generation to their non-transfo rmed parent ('Golden Promise'). A second experiment examined the agron omic characteristics of seven transgenic-derived, null (non-transgenic ) segregant lines in the T-2 and T-4 generations. Compared to their un cultured parent, Golden Promise, most of these lines were shorter, low er yielding, and had smaller seed, and the variability among individua l plants was higher. The frequency and severity of the observed SCV wa s unexpectedly high, and the transformation procedure appeared to indu ce greater SCV than tissue culture in the absence of transformation. A ttempts to understand the sources of SCV, and to modify transformation procedures to reduce the generation of SCV, should be made.