Mathematisch-Naturwissenschaftliche Fakultät

Institut für Biowissenschaften

Fachgebiet: Molekularbiologie (angewandte Pflanzengenetik)

Betreuer: Prof. Dr. Inge Broer

Dipl. Biol. Tobias Latzkow
(e-mail: )

Influence of untranslated regions and terminator sequences on the expression of transgenes under moderate heat stress

Under moderate heat stress conditions both the 5´ untranslated region of the Phosphinothricin-N-acetyltransferase (Pat) gene (pat41) from Streptomyces viridochromogenes (5´ UTR41) and the 3´ termination signal of nopalin synthase gene of Agrobacterium tumefaciens (3´ nos) mediate a reduction of Pat steady state in herbicide resistant tobacco plants (Nicotiana tabacum). While each element alone mediates the reduction only in some transgenic events, others - carrying the same transgene - are unaffected. The combination of the two elements leads to a complete loss of Pat protein and its activity during the heat-treatment. The phenomenon is neither accompanied by a heat-induced reduction of the specific RNA nor influenced by the copy number of the transgene. A fusion of the luciferase coding region (luc) from Photinus pyralis with the 5´ UTR41 and the 3´ nos is similarly inactivated in transgenic tobacco plants. The phenomenon that has up to now only been observed in solanaceous plants was also demonstrated in transgenic Arabidopsis thaliana (Col-0) plants carrying pat genes fused to the 5´ UTR41 and the 3´ nos. However, in contrast to heat-treated tobacco plants only some transgenic events exhibit heat-induce reduction of the transgene encoded protein steady state level, indicating different molecular mechanisms in the cultivars.