Photosynthesis is the starting point of nearly every food chain and sustains much of life on Earth. You’d be forgiven, then, for thinking that nature has perfected the art of turning sunlight into sugar. But this is not entirely true. If you’re struggling with your life goals, it may be reassuring to know that even plants haven’t yet reached their full potential.
Each evolving feature is a balance between the benefit it provides and its energy cost. Plants that we have domesticated for food are good at converting as much sunlight into sugar as they need to survive and reproduce. From a given amount of sunlight, most plants convert less than 5% of this light energy into biomass, and under some conditions less than 1%.
We now have the knowledge and tools to maximize photosynthesis in a variety of food crops; But scientists aren’t investigating how we can help plants get better at photosynthesis out of curiosity. Weather conditions caused by climate change, such as droughts and floods, are destroying crops and threatening crop yields worldwide. This research is about making sure we can grow enough food to feed ourselves.
Many people think of plants as nice-looking greenery. Necessary for clean air, yes, but simple organisms. A step change in research is changing the way scientists think about plants: they are much more complex and more like us than you could imagine. This emerging field of science is too enjoyable to do justice in a story or two.
This article is part of the Plant Enthusiasts series, which explores scientific studies that challenge your perspective on plant life.
Plants such as wheat sometimes mistakenly produce a toxic substance called 2-phosphoglycolate, which then must be recycled within the plant, costing energy. Scientists call this photorespiration. This occurs when rubisco, an enzyme crucial to the photosynthesis process, mistakenly binds to an oxygen molecule instead of carbon dioxide.
Rubisco makes this mistake up to 40% of the time. This is because there is much more oxygen in the atmosphere than in the past, which was deposited there by cyanobacteria (microscopic organisms found in water), the first photosynthesizers. Rising temperatures also cause more photorespiration.
If we can prevent this mistake, we will leave more energy for plants for photosynthesis.
catch the sunlight
Our research project PhotoBoost is investigating how to create a type of internal bypass that reduces photorespiration in rice and potato plants, two of the world’s most important crops.
Just as coronary bypass diverts blood around narrow or blocked arteries in humans, photorespiratory bypass gives plants the genetic tools they need to minimize rubisco’s mistake. Genes from cyanobacteria make this and other photosynthetic developments possible because they contain a set of enzymes for better sunlight management.
Other researchers are looking at plants such as corn, which have developed their own methods of dealing with photorespiration, as an inspiration and gene source for rice.
We also increase the speed at which plants respond to changes in light intensity, as it also affects photosynthesis. When plants get too much sun (when the light is more intense) they shut down their photosynthetic machinery and then may be slow to restart photosynthesis when the weather cools again (for example, when clouds return).
A research group in the US recently showed that accelerating this photoprotection process in soybeans could lead to a 33% increase in seed yield.
At PhotoBoost, we talk to researchers, agronomists, and farmers around the world to understand how we can match society’s needs with this new frontier in plant science. According to colleagues Elizabete Carmo-Silva and Ana Moreira Lobo at Lancaster University: “Climate change, declining yields and water stress pose major challenges for food production this century.”
His team is investigating plant responses to light and temperature, with particular attention to the enzyme rubisco. Higher yields are perhaps the most obvious gain from improving photosynthesis, but it will also help plants be more resilient to drought and heat stress.
new vehicles
Gene editing, a new tool in crop breeders’ arsenal, allows scientists to turn genes on and off and test their effects on plant performance. Once we know their functions, these genes can be suppressed, promoted, or introduced through genetic modification, as has been done in commercial crops since the 1990s.
Nelson Saibo and Isabel Abreu at Universidade Nova de Lisboa in Portugal described how the tools plant breeders have are more “fine-tuning” these days. Their team is using gene editing to improve photosynthesis in rice.
Potato farmers we spoke to recently in the east of England saw greater photosynthetic efficiency as a way of opening up land to nature (for example, planting trees in ancient forest areas or restoring peat bogs in Marshes). More productive plants mean you need less. It is designed to give the same product yield. Their biggest concern was whether major retailers in the UK would be willing to support genetically modified crops.
Besides Photoboost, the European Union also funds other photosynthesis programs through the Gain4crops (sunflower) and Capitalize (tomato, maize and barley) projects. Improving photosynthesis is not a magic solution to most of the agricultural problems we face. But combining knowledge and new tools will help us make the most of light.
This article is republished from The Conversation under a Creative Commons license. Read the original article.
Jonathan Menary receives funding from the European Union
Sebastian Fuller receives funding from the European Commission and the UK National Institute for Health and Care Research
Stefan Schilberg receives funding from the European Union