Plant & Animal Genomes XV Conference Plant & Animal Genomes XV ConferenceJanuary 13-17, 2007
Town & Country Convention Center
San Diego, CA
Serge Remy , Efrén Santos , Els Thiry , Saskia Windelinckx , Ann Hens , Rony Swennen , László Sági
A limited number of genes have so far been isolated and functionally characterized in banana and even less native promoters have been identified. A genome-wide T-DNA tagging strategy has therefore been applied in our laboratory to isolate and characterize novel banana promoters and genes that are potentially useful for the production of transgenic and cisgenic plants.
Firstly, by improvement of the tagging vector novel constitutive promoters were identified and characterized via a high throughput platform that employs sensitive screening for luciferase activation in cell colonies. Activity of a metallothionein type 3 gene promoter and two deletion variants was demonstrated in back-transformed banana plants and rice calli. Inducibility of the metallothionein promoter by ethylene treatment in the original tagged line and back-transformed lines will be discussed. Furthermore, expression of gusA fusions in back-transformed banana lines revealed activity of a promoter from a novel banana gene with high homology to a rice gene of unknown function. Promoter tagged lines with meristem, leaf and root specific luciferase activation have also been identified.
Secondly, this promoter tagging approach was applied for the identification and characterization of several native promoters that are up- or downregulated during in vitro development and/or temperature shifts from 26°C to 8°C. Most tagged lines contained in the cloned T-DNA flanks vector backbone parts and other rearrangements. RT-PCR analysis identified in lines with multiple inserts the sequence that had activated luciferase expression. Two sequences were fused to the gusA reporter gene and back-transformed to banana, which confirmed their promoter activity.