The potato Lhca3.St.1promoter confers high and stable transgene expression in chrysanthemum, in contrast to CaMV-based promoters

Theenhanced cauliflower mosaic virus 35S (dCaMV) promoter and the potatoLhca3.St.1promoter were evaluated for their expressionabilities in chrysanthemum. The promoters were fused to theβ-glucuronidase(GUS) reporter gene with and without flanking matrix-associated regions (MARs).They were transferred into chrysanthemum viaAgrobacterium-mediated transformation. The quantitativeevaluation of GUS activity in a total of 127 independently derivedtransformantsestablished that in chrysanthemum the Lhca3.St.1promoterwas 175 fold more active in the leaves than the dCaMV promoter was. The latterwas as poor in expression as the single CaMV promoter. The use of suchCaMV-based promoters in the genetic engineering of chrysanthemum should bediscouraged when high levels of transgene expression are desired. No clearinfluence of the presence of MARs was observed on the variability of GUS geneexpression, in contrast to earlier studies in tobacco. This may indicate apossible plant species dependent activity of MAR elements.Lhca3.St.1promoter-driven GUS activity was relativelyhigher in the stem of chrysanthemum and proved stable over extensive timeperiods. Therefore this potato promoter is attractive to obtain high expressionlevels in chrysanthemum.