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Rewiring photorespiration using natural and synthetic pathways to sustainably increase crop yield

Periodic Reporting for period 2 - GAIN4CROPS (Rewiring photorespiration using natural and synthetic pathways to sustainably increase crop yield)

Berichtszeitraum: 2021-11-01 bis 2023-04-30

GAIN4CROPS is developing novel disruptive technologies to overcome one of the main constraints of photosynthesis: the photorespiration, a process that reduces CO2 assimilation efficiency, and thus biomass yield and agricultural productivity.

Most plants (85%), including rice, wheat, soybeans and all trees, perform photosynthesis according to the so-called C3 type. At higher temperatures, their photosynthetic efficiency is strongly impaired by photorespiration, which constrains yield. However, some plants have evolved metabolic strategies to bypass this effect: they actively accumulate the CO2 into specific compartments, thus creating an environment unsuitable for photorespiration.

GAIN4CROPS takes inspiration from one of these naturally occurring metabolic strategies and proposes a stepwise approach to enhance the efficiency of photosynthesis. The Consortium aims to optimize the process by designing novel metabolic pathways that make better use of cellular resources by avoiding the release of CO2 back into the atmosphere.

“Attempts to include new metabolisms into crops proved to be very complicated, primarily due to difficulties in introducing a de novo leaf anatomy and fitting in the complex regulatory networks of the cell.” explains the project coordinator Prof. Andreas Weber, from the Institute of Plant Biochemistry of the Heinrich Heine University Düsseldorf. “In GAIN4CROPS, instead, we build on the natural physiology of the sunflower – which has the innate capacity to evolve towards improved metabolisms, ultimately increasing agricultural productivity.”

The Consortium, composed of 3 research organizations (Max Planck Society, CEA and Agroscope), 6 academic institutions (Heinrich Heine University Düsseldorf, University of Rostock, University of Cambridge, University of Padua, Estonian University of Life Science and University of Groningen), 1 industry representative (Corteva Agriscience) and 3 SMEs (IN srl, NRGene Ltd and Genomix4Life), gathers a vast array of expertise and pulls together cutting-edge research on plant physiology, microbiology and system biology with groups that are highly experienced in genome sequencing, plant breeding and field-crops.
During these first three years, the project Consortium has managed to:

- Sequence the genomes of multiple taxa to identify candidates for the C3-C4 carbon pumping mechanism. The species were characterised by various photosynthetic parameters and used to perform phylogenetic association mapping;
- Start interspecific crosses to implement a C3-C4 carbon pump on C3 model species;
- Engineer a mutant that uses different cofactors to study and model a synthetic bypass pathway to natural photorespiration;
- Publish the implementation of a synthetic bypass pathway into Arabidopsis and prepare its implementation into several wild-type and mutant strains;
- Obtain several enzymatic structures that were tested and analysed in diverse mutants, including a demonstration of a complete CO2-reduction pathway in E. coli;
- Model synthesis pathways to identify their integration with native metabolism;
- Define standards for genetic parts library with some parts already constructed;
- Assemble multi-gene constructs for implementation of synthetic bypass pathways. Parts of the pathways have also been assembled;
- Develop an Arabidopsis leaf atlas to integrate data into models;
- Develop predictive modelling and simulation software for estimating yield improvements of different bypass designs;
- Implemented photorespiratory bypasses in patented species and Arabidopsis; the implementation of an improved pathway in Arabidopsis is ongoing;
- Generate and establish a protocol for sunflower transformation in field trails with suitable accessions identified and analysed in replicated field trials.
- Perform the goal and scope phase of the three individual sustainability assessments;
- Analyse the results of a first iteration of a complete Life Cycle Assessment Model;
- Define the methodological framework to conduct a social analysis and assess the techno-economic sustainability of the project, for which the first phase was completed and described.
“With GAIN4CROPS, we join the current efforts to align land use and food production to conserve biodiversity, reduce the environmental impact of agriculture, and deliver sufficient amounts of healthy foods.” says prof. Weber. Indeed, sunflower oil is a healthy alternative to other edible oils, like the palm one.
Overall, the approaches pursued by GAIN4CROPS hold potential for decreasing the use of three major resources in agriculture: land, nitrogen, and water. A more efficient photosynthetic rate brings to greater crop yield per unit area land, which in turn limits the expansion of the arable land and the need for nitrogen fertilizers and water.

The benefits of GAIN4CROPS plants become even more evident at higher temperatures, promoting the development of climate-resilient crops as needed to address the consequences of anthropogenic climate change.The experience gained with GAIN4CROPS will serve as a roadmap to attain similar performances in other plants and pave the way to innovative crops, which, thanks to their climate resilience and reduced resource consumption, might lead to more sustainable agriculture.
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