XVI International Botanical Congess

Tobacco chloroplast DNA contains 105 different genes and 9 hypothetical chloroplast reading frames (ycfs). In order to investigate the function of ycf1, ycf2, ycf5 and ycf6, we analysed the transcript levels in the tobacco leaves and cultured BY-2 cells that lack activity of photosynthesis. Northern blot analysis indicated that ycf1 and 2 transcripts accumulated at a similar level both in leaves and BY-2 cells while ycf5 and 6 transcripts accumulated in leaves but not in BY-2 cells. This strongly suggests that ycf5 and ycf6 are involved in photosynthesis. To further elucidate the function we have constructed the plasmids for targeted deletion of each ycf and carried out chloroplast transformation. Physiological properties of the putative chloroplast transformants are presented.