by Photosynthesis is the starting point for almost every food chain, which sustains most life on earth. You would be forgiven, therefore, for thinking that nature has succeeded in turning the art of sunshine into sugar. But that is not exactly true. If you struggle with life goals, it may be comforting to know that plants have not yet reached their full potential.
Every evolved trait is a trade-off between the benefit it provides and its energy cost. The plants we domesticated are not just for food but for converting sunlight to sugar as they were for survival and reproduction. From a given amount of sunlight, most plants convert less than 5% of that light energy into biomass, and under some conditions, less than 1%.
We now have the knowledge and tools to maximize photosynthesis in a range of food crops – but scientists aren’t just studying how we help plants become better at photosynthesis out of curiosity. Climate change-influenced weather such as droughts and floods are destroying crops and threatening crop yields around the world. This research is about making sure we can grow enough food to feed ourselves.
Many people think of plants as pretty vegetables. Necessary for clean air, yes, but simple organisms. A major shift in research is changing the way scientists think about plants: they are much more complex and more like us than you might imagine. This burgeoning field of science is too exciting to cover in one or two stories.
This article is part of a series, Weird Plant, which explores scientific studies that challenge the way you look at plants.
Plants like wheat sometimes mistakenly produce a toxic substance called 2-phosphoglycolate that must be recycled within the plant, costing it energy. Scientists call this photorespiration. It occurs when an enzyme vital to the photosynthesis process, rubisco, mistakenly replaces a molecule of oxygen with carbon dioxide.
Rubisco makes this mistake up to 40% of the time. It happens because there is much more oxygen in the atmosphere now than in the past, which is put there by the first photosynthesizers, cyanobacteria – microscopic organisms found in water. Elevated temperatures also cause more photorespiration.
If we could prevent this mistake, it would leave more energy from plants for photosynthesis.
Capture the sunlight
Our research project, PhotoBoost, is looking at how to create a kind of internal bypass that reduces photorespiration in rice and potato plants, two of the world’s most important crops.
In the same way that coronary bypass diverts blood around narrow or clogged arteries in humans, the photorespiratory bypass gives plants the genetic tools they need to minimize rubisco error. This and other photosynthetic enhancements are possible with genes from cyanobacteria because they host a range of enzymes to better manage sunlight.
Other researchers are looking at plants such as maize, which have developed their own methods of dealing with photorespiration, as a source of inspiration – and genes – for rice.
We are also improving the speed with which plants respond to changes in light intensity, as this also affects photosynthesis. Plants shut down their photosynthetic machinery if they get too much sun (when the light is more intense), and then they can be slow to resume photosynthesis when it gets colder again – for example, when the clouds roll over.
A research group in the US has recently shown that speeding up this photoprotection process in soybeans can lead to a 33% increase in seed yield.
On PhotoBoost, we are talking to researchers, agronomists and farmers around the world to understand how to match the needs of society with this new frontier in plant science. According to Elizabete Carmo-Silva and Ana Moreira Lobo, colleagues at Lancaster University: “Climate change, declining yields and water stress are major challenges to food production this century.”
Their team investigates plant responses to light and temperature, paying particular attention to the rubisco enzyme. The higher yield is perhaps the most obvious gain from improving photosynthesis, but it will also help make plants more resilient to drought and heat stress.
New tools
A new tool in the arsenal of crop breeders, gene editing, allows scientists to turn genes on and off, testing their effect on plant performance. Once we know their function, these genes can be suppressed, promoted or, as has been done in commercial crops since the 1990s, introduced through genetic modification.
At the Universidade Nova de Lisboa in Portugal, Nelson Saibo and Isabel Abreu told us the tools that plant breeders have these days are “minimal”. Their team is using gene editing to improve photosynthesis in rice.
The potato farmers we spoke to recently in the east of England saw greater photosynthesis efficiency as a way of freeing up land for nature – for example, planting trees on ancient forest sites or restoring peatland in the Fens – as there is less Need more efficient plants. them to give the same top result. Their main concern was whether major UK retailers would be willing to promote genetically engineered crops.
In addition to Photoboost, the European Union is funding other photosynthesis programs through the Gain4crops (sunflower) and Capitalize (tomatoes, maize and barley) projects. Improving photosynthesis is not a silver bullet for many of the agricultural problems we face. But by combining knowledge and new tools, we will help make the most of it.
This article from The Conversation is republished 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 National Institute for Health and Care Research in the UK
Stefan Schillberg receives funding from the European Union
