Periodic Reporting for period 2 - PhotoBoost (A holistic approach to improve the photosynthetic performance and productivity of C3 crops under diverse environmental conditions)
Período documentado: 2021-10-01 hasta 2023-03-31
The PhotoBoost project aims to increase the efficiency of photosynthetic CO2 fixation. This is achieved by developing enhanced C3 crops that combine two or more of the following strategies: a) the optimisation of light reactions; b) the integration of an algal CCM; c) the introduction of an engineered photorespiratory bypass mechanism, improved by the knockout of the native plastid glycolate-glycerate transporter; and d) the optimisation of source-sink capacity, improved by the elevated expression of the phloem-mobile tuberisation signal SP6A, thus enhancing the resilience of heat-sensitive cultivars to climate change. The consortium members have increased photosynthetic efficiency by up to 15% using individual strategies, but the stacking of multiple approaches in the same plant has never been attempted before. We also explore e) the adaptation of stomatal conductance to improve the water-use efficiency, and f) the integration of an O2 scavenging mechanism as a novel strategy to boost photosynthesis. The PhotoBoost project is generating optimised lines representing two major food crops (potato and rice) by simultaneously targeting multiple constraints limiting photosynthetic efficiency. We aim to increase photosynthetic efficiency under diverse environmental conditions by at least 20–25% in terms of photosynthesis rates and by at least 25–30% in terms of biomass yield.
Since its launch in April 2020, the eight international partners have been implementing said strategies within the different work packages (WPs).
Since its launch in April 2020, the eight international partners have been implementing said strategies within the different work packages (WPs).
Within WP1, e-photosynthesis was combined with the Ball-Berry-Woodrow model to improve the representation of stomatal dynamics and optimise water-use efficiency. This enabled calculation of CO2 assimilation and stomatal conductance subject to environmental parameters specified for e-photosynthesis. In addition, crop-specific kinetic parameters and rate equations were introduced to improve the representation of the mechanisms underlying non-steady-state photosynthesis in the e-photosynthesis model. Through optimising the model to ascertain the enzyme distribution that would maximise light-saturated CO2 assimilation, we identified the changes in enzyme concentrations necessary to increase crop photosynthetic efficiency.
In WP2, a photosynthetically active cell-free system derived from tobacco BY-2 cells and supplemented with chloroplasts has been generated and can be used to screen and optimize chloroplast targeting efficiency of recombinant proteins. Furthermore, a protocol for highly efficient transformation of green Arabidopsis cells has been established.
In WP3, fast-track elite OXY (oxygen scavenging, strategy f) and PRB (photorespiratory bypass, strategy c) potato lines showing increased photosynthetic efficiency of 16-17% and tuber yield of 28-32% have been generated. Thus, both strategies are suitable to increase photosynthetic performance and tuber yield, and contribute to the successful achievement of milestone MS3. In addition, the WP3 partners completed the design and construction of the advanced-track multigene potato and rice transformation vectors combining the most successful strategies that will be used for potato and rice transformation in the advanced-track approach. Transformation of potato and rice plants with the final advanced-track expression vectors has been initiated.
In WP4, comprehensive physiological and photosynthetic evaluation of the new fast-track potato lines resulted on selection of promising advanced-track strategies. First elite OXY, PRB, Sp6A and VPZ potato lines are available for field trials, which will be conducted at KWS between May-October 2023.
Within WP5, a detailed biochemical characterisation has been initiated with the transgenic LR (light reaction, strategy a), OXY and PRB potato plants analysed in WP4, to evaluate the impact of multi-gene expression on the accumulation of photosynthetic end-product (glucose, fructose, sucrose, starch) as well as the primary metabolites. Further experiments are ongoing to support and strengthen our preliminary results.
For WP6, we have started focus groups consisting of stakeholders from across the rice and potato sectors in the UK and Philippines. Future workshops will involve stakeholders from another European country and one further low- or middle-income country. Although formal analysis is ongoing, several emerging themes highlight the importance of breeders choosing locally-adapted varieties when licensing future PhotoBoost improvements and optimism around new genomic techniques to provide solutions to on-farm challenges.
In WP2, a photosynthetically active cell-free system derived from tobacco BY-2 cells and supplemented with chloroplasts has been generated and can be used to screen and optimize chloroplast targeting efficiency of recombinant proteins. Furthermore, a protocol for highly efficient transformation of green Arabidopsis cells has been established.
In WP3, fast-track elite OXY (oxygen scavenging, strategy f) and PRB (photorespiratory bypass, strategy c) potato lines showing increased photosynthetic efficiency of 16-17% and tuber yield of 28-32% have been generated. Thus, both strategies are suitable to increase photosynthetic performance and tuber yield, and contribute to the successful achievement of milestone MS3. In addition, the WP3 partners completed the design and construction of the advanced-track multigene potato and rice transformation vectors combining the most successful strategies that will be used for potato and rice transformation in the advanced-track approach. Transformation of potato and rice plants with the final advanced-track expression vectors has been initiated.
In WP4, comprehensive physiological and photosynthetic evaluation of the new fast-track potato lines resulted on selection of promising advanced-track strategies. First elite OXY, PRB, Sp6A and VPZ potato lines are available for field trials, which will be conducted at KWS between May-October 2023.
Within WP5, a detailed biochemical characterisation has been initiated with the transgenic LR (light reaction, strategy a), OXY and PRB potato plants analysed in WP4, to evaluate the impact of multi-gene expression on the accumulation of photosynthetic end-product (glucose, fructose, sucrose, starch) as well as the primary metabolites. Further experiments are ongoing to support and strengthen our preliminary results.
For WP6, we have started focus groups consisting of stakeholders from across the rice and potato sectors in the UK and Philippines. Future workshops will involve stakeholders from another European country and one further low- or middle-income country. Although formal analysis is ongoing, several emerging themes highlight the importance of breeders choosing locally-adapted varieties when licensing future PhotoBoost improvements and optimism around new genomic techniques to provide solutions to on-farm challenges.
So far, photosynthetic efficiency of fast-track elite potato lines has been increased by 16-17% and tuber yield by 28-32%, which is well above the 10 % target mentioned in the call. Further improvement in photosynthetic performance and biomass yield is expected when different strategies are combined in potato and rice. Our goal is to increase photosynthetic efficiency under different environmental conditions by at least 20-25 % in terms of photosynthetic rates and by at least 25-30 % in terms of biomass yield.