Expression of introduced genes after tuber propagation of transgenic potato plants

The stability of expression of alien genes was analysed in transgenic plants of the potato cv. ‘Bintje’ during successive tuber generations. Three generations of four shoot lines selected on the presence or absence of expression of genes, originating from the Agrobacterium strain LBA1060KG, were investigated. Six traits (presence of opines, leaf form, plant habit, tuber form, GUS activity and kanamycin resistance) caused by the expression of marker loci from TR- and TL-DNAs of A. rhizogenes strain LBA9402 and TKG-DNA from pBI121 plasmid were analysed. The quantitative analysis of the traits was carried out in 272 plants. In all, 1224 observations were made for the six traits. No variation in the expression of introduced genes was observed among the tuber progeny plants. It was remarkable that none of the silent genes (rolA and GUS in 252 and 168 plants, respectively) was activated in the tuber progeny. Moreover, consistent expression of genes that affect plant development (rolA and rolC with 816 observations) as well as plant neutral genes (opine, GUS and NPTII with 408 observations) was observed. The results indicate that there was no difference in stability of expression between transgenes and resident genes during vegetative propagation through tubers.