Download Dr. Andrea Bräutigam

INSTITUT FÜR BIOLOGIE UND UMWELTWISSENSCHAFTEN
Einladung zum Vortrag
im Rahmen des Kolloquiums Biologie und Umweltwissenschaften
Dr. Andrea Bräutigam
Heinrich-Heine-Universität Düsseldorf
Towards a blueprint of C4 photosynthesis
C4 photosynthesis enables efficient carbon fixation even under resource-limited conditions. It
represents an adaptation to high light conditions, low water availability and high temperatures. The
potential of C4 photosynthesis was harnessed in ancient times in Mesoamerica by breeding a wild C4
progenitor into Zea mays, a species with amazingly high biomass accumulation. For this reason, C4
photosynthesis is a candidate pathway for a second green revolution (i.e. the C4 rice project). The C4
photosynthetic trait is a complex trait; that means it requires changes in multiple loci. C4
photosynthesis has evolved independently at least 60 times in multiple different plant lineages of
both monocots and dicots. C4 photosynthesis requires alterations to the biochemistry (at least
enzyme and transport protein activities), cellular architecture (at least cell wall composition,
plasmodesmata density, organelle content) and tissue architecture (vein spacing). We hypothesized
that a global systemic analysis will reveal the extent of transcriptional regulation of known C4-related
genes, identify potential regulators of C4 genes and generate new candidate genes and pathways
necessary for C4 photosynthesis. By dissecting the trait it may not only become possible to
reassemble it in a crop species but also to understand the evolutionary steps leading towards it.
We employ next generation sequencing (NGS) to generate gene expression data and sequence
information at the same time, with technologies collectively called RNA-Seq. To analyze the data we
have generated in-house pipelines that produce and quality-control annotated assemblies and that
generate gene expression data by mapping either within the species or across species. Two different
technologies (454/Roche and Illumina), several assemblers and two different mapping algorithms
were tested. RNA-Seq is combined with enzyme activity measurements, metabolite profiles and
imaging to compare closely related species pairs or sets which include species with and without the
complex trait. The methods have been successfully used for a pairwise comparison in the
Cleomaceae and for the analysis of five Flaverias including an intermediate species. Selected C4
candidate genes were identified and further analyzed. We have recently expanded the analysis to
include grass species such as Z. mays, Panicum clandestinum and Panicum maximum and extended
the analysis of already sequenced species to include multiple tissues and developmental stages. I will
present our current model of C4 photosynthesis including recently identified additions to the core
cycle.
05.06.2012, 16 Uhr c.t., W04 1-162
Gäste aller Institute sind herzlich willkommen
Gastgeber: Prof. Dr. Dirk Albach