Plant biotechnology beyond genome era in the dawn of synthetic biology

Plant biotechnology is considered to have started from the discovery of the principles of cellular totipotency in the late 19th century, followed by Agrobacterium-mediated genetic transformation about 45 years ago. Today, the two main pilars of plant biotechnology are the possibilities to utilize efficiently living plant cells as green factories to produce highly complex small molecules (secondary metabolities), and recombinant proteins. On the other hand, plant biotechnology offers also valuable tools for plant breeding, e.g. introducing novel traits to crop or ornamental plants, nowadays also through new plant breeding techniques with unprecedented efficiency.
The main bottleneck in producing efficiently plant seconday metabolites has been the lack of understanding of how these complex molecules are synthetized and regulated in plant cells. The tissue-specific and subcellular localization adds an extra challenge to this picture.
Moreover, only recently the rapid and more economic genome sequencing tools have allowed to obtain genome data, also from non-model plants, thus permitting the modelling of biosynthetic pathways. We are now able to utilize synthetic biology tools to readily map the key genes playing the major roles in pathway engineering, as well as producing entirely new-to-nature molecules with novel acivities through combinatorial biochemistry.
Examples of metabolic engineering of pharmaceutically important plant metabolites in plants and plant cells as well as possibilities to transfer entire pathways to simpler organisms such as yeast will be given. Plant cells can also be used for biotransformation as will be illustrated with the example of a raspberry ketone flavour coumpound. To overcome the additional bottleneck related to the instability of the undifferentiated cell cultures, we have shown the metabolic stability of hairy root cultures for more than 15 years of cultivation.
Recombinant protein production in plants and plant cell cultures has resulted in excellent outcomes, especially for pharmaceutical applications. These discoveries will also be highlighted.