Page 247 - PC2019 Program & Proceedings

PLANT CANADA 2019

P67. Enhancing yield and biomass in canola by modifying carbohydrate metabolism
Wang, L.; Y. Wang; A. Makhmoudova; I. Tetlow; M. Emes
University of Guelph

Carbohydrates such as starch provide the stored energy reserves of plants. We previously developed a
novel technology which caused a remarkable boost in seed yield in Arabidopsis by modifying starch
metabolism. When the Arabidopsis endogenous leaf starch branching enzymes (SBEs) were replaced with
maize endosperm homologues ZmSBEI or ZmSBEIIb, the plants demonstrated significant increases in
starch biosynthesis and a dramatic increase in seed production. Canola (Brassica napus L.) is genetically
close to Arabidopsis with highly conserved gene functions between the two species. The homologous
SBEs in canola are assembled on both A and C genomes with very high identities to those in Arabidopsis.
This provided a feasible strategy to apply the above technology to canola. Canola is allotetraploid with a
more complicated genetic background and, since no SBE knockout mutants are so far publicly available,
generation of a Bnsbe null mutant becomes a critical step for replication of this effect in canola. Gene
editing using the CRISPR/Cas9 system has been applied to edit the endogenous SBEs and transgenic
plants obtained through Agrobacterium-mediated transformation of cotyledons. Mutant lines containing
different copies of SBEs have been characterized and the advantage of gene editing in canola and other
crops are discussed.

Liping Wang (lwang10@uoguelph.ca)

P68. Recent advances in plant ubiquinone (Coenzyme Q) biosynthesis and engineering
1
1
1
1
1
1
1
2
Soubeyrand, E. ; T. Johnson ; S. Latimer ; A. Bernert ; M. Kelly ; J. Kim ; T. Colquhoun ; A. Block ; G.
Basset
1
1 University of Florida
2 USDA
Ubiquinone is a liposoluble and redox-active molecule that is made up of benzenoid and prenyl moieties.
It serves as a vital electron carrier in the respiratory chain of mitochondria and some bacteria, and doubles
as a potent lipid and protein antioxidant. Recent evidence from our laboratory indicates that land plants
have evolved the unprecedented ability to derive the benzenoid ring of ubiquinone from the metabolism
of phenylpropanoids (Plant Cell 26: 1938-1948). I will present data from gene network modeling
combined with reverse genetics and isotopic tracer experiments in Arabidopsis and tomato that
demonstrate that the cognate metabolic architecture is split into two branches, the first one originating
from the β-oxidation of p-coumarate in peroxisomes, while the second one stems from the peroxidative
cleavage of a flavonol, called kaempferol, in the cytosol (Plant Cell 30: 2910-2921). Having dissected the
molecular determinants of such a cleavage, I will show that using a synthetic biology approach it is
possible to capture this catabolic branch to re-route kaempferol towards the accumulation of ubiquinone
in Arabidopsis leaves and tomato fruits. I will briefly discuss how this paradigm shift regarding the
functional significance of flavonols in plant tissues offers new opportunities for increasing the nutritional
value and stress resistance of crops.

Eric Soubeyrand (esoubeyrand2@ufl.edu)

Page 245 of 339