Improving Rubisco the Enzyme that Converts CO2 Into Energy
A study led by academics from the University of Liverpool has identified a novel method for improving crop growth, addressing the significant difficulty of increasing food yield in a changing environment with a growing population.
With global CO2 levels rising and the population expected to reach over 10bn by 2050, Professor Luning Liu’s team employed synthetic biology and plant engineering approaches to improve photosynthesis, developing a template that may be applied on a large scale.
Photosynthesis is the process by which plants absorb CO2 from the atmosphere to produce nutrients that are essential for growth and global ecology. The newly released report describes how the researchers improved Rubisco, a critical enzyme in photosynthesis that turns CO2 into energy. Rubisco is typically inefficient and hinders photosynthesis in important crops. Many microorganisms, including bacteria, have evolved effective systems known as ‘CO2-concentrating mechanisms’ to boost Rubisco.
The team was inspired by nature and successfully designed a catalytically quicker Rubisco derived from bacteria into tobacco plant cells that perform photosynthesis to boost plant growth. The new approach increases the stability and ability of the Rubisco to turn CO2 into energy, helping plants to develop even more. Changes to the enzyme may also boost the plant’s ability to absorb CO2, contributing to the worldwide effort to combat climate change.
“We are extremely excited about this breakthrough. Overall, our findings provide proof-of-concept for a route to improving crop development and production that can withstand changing climates and meet the growing food requirements of the world’s expanding population,” Luning Liu, Department of Biochemistry and Systems Biology, University of Liverpool said.
Bacterial Form II Rubisco Can Support Wild-type Growth and Productivity in Potatoes
Over the last decade, tremendous progress has been made in the development of techniques for enhancing both the light harvesting and carbon fixation pathways of photosynthesis through nuclear transformation, with many incorporating multigene synthetic biology approaches.
As efforts to transfer these successes from tobacco to crops pick up steam, the variety of transgenic alternatives available, including the capacity to alter crop photosynthesis through chloroplast transformation, has to be similarly diversified. To address this need, a team of researchers led by Tahnee Manning dug deep into the first transplastomic modification of photosynthesis in a crop by replacing the native Rubisco in potato with the faster, but lower CO2-affinity and poorer CO2/O2 specificity Rubisco from the bacterium Rhodospirillum rubrum.
“Here, we develop the first photosynthetically modified plastome transformed food crop by substituting the native CO2-fixing enzyme, Rubisco, in potato with a faster primitive variant from the bacterium Rhodospirillum rubrum. Though the poor CO2-affinity of the structurally simple bacterial Rubisco impaired leaf carbon assimilation rates in the air (ambient CO2), the transplastomic potato lines showed wild-type vegetative growth, leaf nutrient quality, carbohydrate content, and tuber production under elevated CO2. Our data support observations that the sink strength in the potato will allow for up to approximately 30% improvements over current tuber yields via enhancing photosynthate production (source strength),” the experts say.
Numerous biotechnology and breeding initiatives aimed at enhancing crop resilience, nutrition, and yield are supported by the urgent global concern about food security. The need to manage the escalating frequency of extreme weather events, the diminishing quality and availability of arable land, and the quickly shifting rainfall patterns present challenges to these efforts. To promote photosynthesis and increase crop productivity, there has been a rise in interest and research in recent years.
Studies with the model C3-plant tobacco have identified a range of strategies for improving growth rates in the field. Examples include increasing light-harvesting capacity, re-engineering photorespiration to increase CO2 release at the site of Rubisco in the chloroplast, and enhancing the regeneration of Rubisco’s substrate Ribulose-1,5-bisphosphate (RuBP) under high light. In some instances, these strategies have been successfully translated into crop-enhancing outcomes with the level of success in yield gain heavily dependent on plant sink potential and resource (water, nitrogen) availability.