Improvement in wheat carbon flux for increased yield and harvest index
AWC contribution: $150,000.00
Start Date: April 1, 2015
End Date: March 31, 2019
Summary:
This 4 year project proposes to increase grain yield by manipulating the cellular carbon flux to improve productivity in wheat varieties. By using genome editing technology, the primary regulatory enzyme (mitochondrial pyruvate dehydrogenase complex kinase, mtPDHK) for photosynthetic production will be altered to increase seed size and weight. Previous studies have shown that gene silencing of mtPDHK yielded an increase of carbon flux and Harvest Index in Arabidopsis plant.
Objectives:
to develop an improved wheat line with increased photosynthetic productivity and Harvest Index.
Benefit to producers:
By improving wheat yield and productivity using a novel, but non-GMO molecular approach, Albertan and Canadian Prairie wheat will have a higher competitiveness on the global market.
Bio:
Dr. Elizabeth-France Marillia is a plant molecular geneticist with the National Research Council of Canada where she has been working on plant biotechnology since 1996. She earned her PhD in plant genetics at the University of Saskatchewan. Her research interests include genetic improvement of oilseed crops such as Brassica carinata to produce industrially high value-added specialized oils. Her work has lead to the discovery of several key lipid genes and their genetic manipulation for enhanced oil production. Her contributions to the field has been published extensively in international peer-reviewed journals and covered by several patents. She is now involved in the development of improved wheat cultivars with increased yield using gene editing technology in collaboration with AAFC.
Project Completion Report:
This project proposed to increase grain yield in wheat by manipulating cellular carbon flux for the production of improved varieties with higher productivity. More specifically, the objective was to modulate the activity of a key regulatory enzyme, the mitochondrial Pyruvate Dehydrogenase Kinase (mt PDHK), for higher carbon metabolism and subsequent increase in seed weight and Harvest Index, in order to increase competitiveness of Canadian wheat farmers on the global market.
A production platform was developed, based on cell culture and gene editing technologies in order to genetically modify wheat embryos and regenerate mature and fertile plants mutated at the desired site of the target gene. We first focused on Cell Penetrating Peptides (CPPs) technology to deliver CRISPR/Cas9 nucleases into haploid cells. However, our efforts to apply this approach originally developed in triticale did not reach satisfying results in wheat and the more established biolistics technology was instead undertaken for the rest of the project. Our efforts resulted in the creation, at the embryo level, of several single nucleotide mutations at the expected site of the mt PDHK gene.
Having validated the CRISPR technology in embryos, we next focused on the regeneration of green plantlets from embryos, another technical major challenge in wheat. To that end, a large part of the project was devoted to establishing an efficient genetic transformation pipeline for wheat cultivars, which included the testing of various chemicals to increase tissue culture response for enhanced production of plantlets. A breakthrough came in the last year of the project with the discovery of a class of molecular enhancers that have the ability to significantly increase somatic embryogenesis (SE) to levels necessary for the development of any high throughput crop improvement platforms. This novel, chemical-based (but phytohormone-independent), approach allows, through the induction of SE-related genes, for the improvement of embryogenesis in a non-GMO fashion.
In conclusion, several significant breakthroughs were reached during this four year project, the most important one being the establishment of a solid working wheat transformation platform that can be applied, through our proprietary SE chemical enhancer technology, to any other crop of interest (patent pending). In our view, this milestone alone represents a major -and key- step forward in the progress made in gene editing technology applied to wheat and other crops improvement. Of note, in a parallel and proof of concept study based on an anti-sense approach, our mutated lines were assayed for their PDC activity and most of them displayed the expected increase in activity, as a result of repressing its down-regulator, the mt PDHK.