Enhancing crop yields through improvements in the efficiency of photosynthesis and respiration

Published online January 2023The rate with which crop yields per hectare increase each year is plateauing at the same time that human population growth and other factors increase food demand. Increasing yield potential (Yp) of crops is vital to address these challenges. In this review, we explore a component of Yp that has yet to be optimised – that being improvements in the efficiency with which light energy is converted into biomass (ϵc) via modifications to CO2 fixed per unit quantum of light (α), efficiency of respiratory ATP production (ϵprod) and efficiency of ATP use (ϵuse). For α, targets include changes in photoprotective machinery, ribulose bisphosphate carboxylase/oxygenase kinetics and photorespiratory pathways. There is also potential for ϵprod to be increased via targeted changes to the expression of the alternative oxidase and mitochondrial uncoupling pathways. Similarly, there are possibilities to improve ϵuse via changes to the ATP costs of phloem loading, nutrient uptake, futile cycles and/or protein/membrane turnover. Recently developed high-throughput measurements of respiration can serve as a proxy for the cumulative energy cost of these processes. There are thus exciting opportunities to use our growing knowledge of factors influencing the efficiency of photosynthesis and respiration to create a step-change in yield potential of globally important crops.Andres Garcia, Oorbessy Gaju, Andrew F. Bowerman, Sally A. Buck, John R. Evans, Robert T. Furbank, Matthew Gilliham, A. Harvey Millar, Barry J. Pogson, Matthew P. Reynolds, Yong-Ling Ruan, Nicolas L. Taylor, Stephen D. Tyerman, and Owen K. Atki

Glastir Monitoring & Evaluation Programme. Final report

Final Report to Welsh Government, prepared by CEH on behalf of the Glastir Monitoring & Evaluation Programme Team. The Glastir Monitoring and Evaluation Programme (GMEP) provides a comprehensive programme to establish a baseline against which future assessments of Glastir can be made. GMEP also contributes national trend data which supports a range of national and international biodiversity and environmental targets. GMEP fulfils a commitment by the Welsh Government to establish a monitoring programme concurrently with the launch of the Glastir scheme. The use of models and farmer surveys provides early indicators of the likely direction, magnitude and timing of future outcomes. The programme ensures compliance with the rigorous requirements of the European Commission’s Common Monitoring and Evaluation Framework (CMEF) through the Rural Development Plan (RDP) for Wales. This report represents the final results of the GMEP programme which ran from 2012 to 2016

Effects of altered α - and β -branch carotenoid biosynthesis on photoprotection and whole-plant acclimation of Arabidopsis to photo-oxidative stress

Functions of α- and β-branch carotenoids in whole-plant acclimation to photo-oxidative stress were studied in Arabidopsis thaliana wild-type (wt) and carotenoid mutants, lutein deficient (lut2, lut5), non-photochemical quenching1 (npq1) and suppressor of zeaxanthin-less1 (szl1) npq1 double mutant. Photo-oxidative stress was applied by exposing plants to sunflecks. The sunflecks caused reduction of chlorophyll content in all plants, but more severely in those having high α- to β-branch carotenoid composition (α/β-ratio) (lut5, szl1npq1). While this did not alter carotenoid composition in wt or lut2, which accumulates only β-branch carotenoids, increased xanthophyll levels were found in the mutants with high α/β-ratios (lut5, szl1npq1) or without xanthophyll-cycle operation (npq1, szl1npq1). The PsbS protein content increased in all sunfleck plants but lut2. These changes were accompanied by no change (npq1, szl1npq1) or enhanced capacity (wt, lut5) of NPQ. Leaf mass per area increased in lut2, but decreased in wt and lut5 that showed increased NPQ. The sunflecks decelerated primary root growth in wt and npq1 having normal α/β-ratios, but suppressed lateral root formation in lut5 and szl1npq1 having high α/β-ratios. The results highlight the importance of proper regulation of the α- and β-branch carotenoid pathways for whole-plant acclimation, not only leaf photoprotection, under photo-oxidative stress

Potential abiotic stress targets for modern genetic manipulation.

Research into crop yield and resilience has underpinned global food security, evident in yields tripling in the past five decades. The challenges that global agriculture now faces are not just to feed 10+ billion people within a generation, but to do so under a harsher, more variable and less predictable climate, and in many cases with less water, more expensive inputs and declining soil quality. The challenges of climate change are not simply to breed for a "hotter drier climate", but to enable resilience to floods and droughts and to frosts and heat waves, possibly even within a single growing season. How well we prepare for the coming decades of climate variability will depend on our ability to modify current practices and innovate with novel breeding methods, and to communicate and work with farming communities to ensure viability and profitability. Here we define how future climates will impact farming systems and growing seasons, thereby identifying the traits and practices needed and including exemplars being implemented and developed. Critically, this review will also consider societal perspectives and public engagement about emerging technologies for climate resilience, with participatory approaches presented as the best approach.Andrew F. Bowerman, Caitlin S. Byrt, Stuart John Roy, Spencer M. Whitney, Jenny C. Mortimer, Rachel A. Ankeny, Matthew Gilliham, Dabing Zhang, Anthony A. Millar, Greg J. Rebetzke, and Barry J. Pogso

Addressing Research Bottlenecks to Crop Productivity

Asymmetry of investment in crop research leads to knowledge gaps and lost opportunities to accelerate genetic gain through identifying new sources and combinations of traits and alleles. On the basis of consultation with scientists from most major seed companies, we identified several research areas with three common features: (i) relatively underrepresented in the literature; (ii) high probability of boosting productivity in a wide range of crops and environments; and (iii) could be researched in ‘precompetitive’ space, leveraging previous knowledge, and thereby improving models that guide crop breeding and management decisions. Areas identified included research into hormones, recombination, respiration, roots, and source–sink, which, along with new opportunities in phenomics, genomics, and bioinformatics, make it more feasible to explore crop genetic resources and improve breeding strategies