Retro Transposon-Based Marking from Potato Monoploids Utilized As a Part of Somatic Hybridization |
IRAP(Inter-Retrotransposon Amplified Polymorphism) is a PCR (polymerase chainreaction) based marker technique that uses the proximity of LTR (long terminalrepeat) regions of adjacent retrotransposons to generate markers by use ofoutward facing primers that anneal to LTR target sequences. The LTR regionstend to be highly conserved because they contain sequences, essential forexpression. New insertions lead to polymorphism in IRAP banding patterns. Ourprimers were designed to target the LTR of potato Tst1 retrotransposons todetect head-to-head orientation. The potato population under investigationconsisted of regenerants following electrofusion of genetically distinct pairsof monoploids (2n=1x=12). Both somaclones from unfused parental protoplasts andsomatic hybrids from actual fusions were generated. The IRAP procedure led toamplification of over 78 bands, of these 2 were unique and clearlydistinguished the somatic hybrids from the somaclones among the regeneratedplants. IRAP produced more bands when compared with AFLP. However, polymorphicbanding patterns, which could be associated with activation ofretrotransposons, were low (4%) suggesting that the Tst1 retrotransposon wasinactive during the protoplast-to-plant process. Fragment analysis revealedhigh sequence similarities to distantly related Solanaceae implying that thisis an ancient retrotransposon.