281:	Resiratory studies of wild-type and transgenic Arabidopsis thaliana (Columbia) cell cultures.

Authors:	Johnson, Felicity(A)Dry, Ian, B.(B)Wiskich, Joseph, T.(A)
Affiliations:	(A): The University of Adelaide, Department of Environmental Biology (B): CSIRO Plant Industry, Horticulture Unit
Presenter:	Johnson, Felicity , fjohnson@botany.adelaide.edu.au

Transgenic cell cultures of A.thaliana were investigated to discern any effects of the inducible aox1a antisense construct present in the transgenic cell line. This culture was made from previously described copper-inducible aox1a antisense plant line (Johnson Potter et al. submitted). Within the cultures, the construct did not appear to function as expected. Wild-type (wt) and transgenic cultures were tested over a 5 day period during which the cultures sensitivity to the alternative pathway (AP) inhibitor SHAM (measured as a percentage of the control rate) was found to differ, while the sensitivity to KCN remained approximately the same. Transgenic cells developed maximal SHAM sensitivity during the second day after subculturing, while wt cells remained at a significantly lower values throughout the period of measurement. The presence of the inducer (5uM CuSO4) had little or no effect on the transgenic cells1 response. Mitochondria were purified from both cultures on day 4 after subculturing, and those from the transgenic cells showed a greater sensitivity to the alternative oxidase inhibitor n-propyl gallate (n-PG) with obviously lower rates after n-PG addition than the wt mitochondria. The CP inhibitor myxothiazol (MYX) had similar effects on both wt and transgenic mitochondria, however there was a trend towards less MYX sensitivity (measured as a percentage of the control rate) and higher respiratory rates, in the presence of MYX, in the mitochondria from transgenic cells. The comparatively higher respiratory rates in the presence of MYX occurred despite the overall lower control rate displayed by mitochondria from the transgenic line. These results indicate that the transgenic cell culture had increased AP activity, despite containing an antisense construct.