Fate of introduced genetic markers in transformed root clones and regenerated plants of monohaploid and diploid potato genotypes.

Agrobacterium transformation of stem internodes of four monohaploid (839-79, 849-7, 851-23, 855-1) and two diploid (M9 and HH260) potato genotypes using hairy root-inducing single (LBA 1020, LBA 9365, LBA 9402) and binary (LBA 1060KG) vectors is reported. Various media and successive culture steps were tested for plant regeneration from different transformed root clones. The fate of introduced genetic markers in root clones and regenerated plants (hairy root phenotype, hormone autotrophy, opine production, kanamycin resistance, β-glucuronidase activity), the ploidy stability and protoplast yield were analysed. The transformation efficiency of stem internodes (hairy root production) and the regeneration capacity of the transformed root clones greatly differed within and between the various potato genotypes. The regenerated plants obtained after transformation with both types of vectors often showed the absence of one or more genetic markers. However, transformation with the binary Agrobacterium vector generally resulted in the stable presence of the opines in all transformed root clones and most regenerated plants. In HH260, transformation efficiency, plant regeneration of transformed root clones, protoplast yield and ploidy stability were the highest as compared to the other genotypes. The application of these transformed plants as marker lines in gene mapping and gene expression studies is indicated.