Marine algae implants could boost crop yields
Discovery could lead to more sustainable food supply
IMAGE:
FLUORESCENCE IMAGE OF CORAL ACROPORA JUVENILE POLYPS HOSTING THE SYMBIOTIC ALGAE (BREVIOLUM MINUTUM) THAT WAS USED IN THE RESEARCH PAPER, SHOWN AS RED DOTS. GREEN COLOR IS THE ENDOGENOUS GREEN FLUORESCENCE FROM CORALS.
view moreCREDIT: ROBERT JINKERSON/TINGTING XIANG/UCR
Scientists have discovered the gene that enables marine algae to make a unique type of chlorophyll. They successfully implanted this gene in a land plant, paving the way for better crop yields on less land.
Finding the gene solves a long-standing mystery amongst scientists about the molecular pathways that allow the algae to manufacture this chlorophyll and survive.
“Marine algae produce half of all the oxygen we breathe, even more than plants on land. And they feed huge food webs, fish that get eaten by mammals and humans,” said UC Riverside assistant professor of bioengineering and lead study author Tingting Xiang. “Despite their global significance, we did not understand the genetic basis for the algae’s survival, until now.”
The study, published in Current Biology, also documents another first-of-its-kind achievement: demonstrating that a land plant could produce the marine chlorophyll. Tobacco plants were used for this experiment, but in theory, any land plant may be able to incorporate the marine algae gene, allowing them to absorb a fuller spectrum of light and achieve better growth.
Chlorophyll is a pigment that enables photosynthesis, the process of converting light into “food,” or chemical energy. Plants produce chlorophyll a and b, while most marine algae and kelp produce c, which enables them to absorb the blue-green light that reaches the water.
“Chlorophylls b and c absorb light at different wavelengths,” said Xiang. “The ocean absorbs red light, which is why it looks blue. Chlorophyll c evolved to capture the blue-green light that penetrates deeper into the water.”
An additional application of this research could be in the production of algae biofuels. There are a few algae species that produce chlorophylls a or b like land plants, instead of c. Imbuing those algae with the gene to make chlorophyll c could also enhance their ability to use more light and increase their growth, creating more feedstock for the fuels.
The researchers initially set out to gain insight into an algae species that lives in coral. These algae manufacture sugars and share them with their coral hosts. “Each coral colony has thousands of polyps, and their brown color is from the algae. Whenever you see coral bleaching, it’s due to the loss of the algae,” Xiang said.
Interested in how the algae’s ability to do photosynthesis would affect the coral, the researchers worked with mutant algae as an experiment. These rare mutants were more yellow in color than their brown relatives and were unable to perform photosynthesis. They found, unexpectedly, that in coral, these mutant algae were still able to live and grow because the coral gives the algae sustenance to grow.
As luck would have it, by using next-generation DNA sequencing and a lot of data analysis, the researchers were also able to use the mutants to discover the gene responsible for chlorophyll c production. “Discovering the chlorophyll c gene was not the initial goal of our work. We made the mutants for another reason, but I guess we were just lucky,” Xiang said.
With new insight into the genetic basis for producing chlorophyll c, the researchers are hopeful that the work could eventually help stem the tide of coral bleaching seen worldwide. Furthermore, there are land-based applications that could help people adapt to climate change.
"The identification of the biosynthetic pathway for chlorophyll c is more than a scientific curiosity; it's a potential game-changer for sustainable energy and food security,” said Robert Jinkerson, UCR chemical engineering professor and study co-author.
“By unlocking the secrets of this key pigment, we're not only gaining insights into the lifeblood of marine ecosystems but also pioneering a path towards developing more robust crops and efficient biofuels,” Jinkerson said.
JOURNAL
Current Biology
ARTICLE TITLE
Biosynthesis of chlorophyll c in a dinoflagellate and heterologous production in planta
Nicotiana benthamiana or tobacco plants, as used in a test of whether they could express marine chlorophyll c genes.
CREDIT
Robert Jinkerson/Tingting Xiang/UCR
The world’s most prolific CO2-fixing enzyme is slowly getting better
New research led by the University of Oxford has found that rubisco – the enzyme that fuels all life on Earth – is not stuck in an evolutionary rut after all. The largest analysis of rubisco ever has found that it is improving all the time – just very, very slowly. These insights could potentially open up new routes to strengthen food security. The results have been published today in Proceedings of the National Academy of Sciences [PNAS].
The most abundant enzyme on Earth, rubisco, has been providing the energy which fuels life on our planet for the last three billion years. While rubisco fixes billions of tons of CO2 each year, the enzyme is notoriously inefficient. This has created a biological paradox that has puzzled researchers for decades. Why is the enzyme that has been fuelling life for over 3 billion years not much better at doing its job? Many plant scientists have debated whether the enzyme is stuck in an 'evolutionary rut', making it impossible for it to get any better.
But new research from the University of Oxford has revealed that rubisco is continually improving, but that this improvement is occurring at a glacial pace.
Lead author Jacques Bouvier (a DPhil student in the Department of Biology, University of Oxford) said: ‘Our research demonstrates for the first time that evolution is consistently improving rubisco and that further improvement of the enzyme is possible. Importantly, this insight provides renewed optimism for efforts to engineer the enzyme to help feed the world.’
The researchers analysed rubisco gene sequences from across a wide range of photosynthetic organisms and quantified the rate of rubisco evolution for the first time. They found that its sequence has altered in minute increments of just one DNA base change every 900,000 years – a stark contrast from the COVID-19 genome, for example, which is evolving one base change every two weeks. This puts rubisco in the 1% of slowest evolving genes on Earth.
Despite this slow rate of change, the researchers found that the enzyme is harnessing this evolution to get better at fixing CO2. The authors also found that this slowly improving CO2 fixation is resulting in improvements to photosynthesis; plants are evolving to get better at turning CO2 into sugar, but the rate of improvement is so slow that it appears frozen.
For decades scientists have aspired to engineer an improved rubisco to boost growth and yields of crop plants. But despite much effort, success has been limited, and many have wondered whether rubisco is already optimised, making these attempts futile. However, the insights from this study offer renewed hope. In particular, unravelling the mystery of what is holding back rubisco’s rate of evolution may uncover new ways of enhancing crop yields.
Jacques Bouvier added: 'Because rubisco assimilates the sugars which fuel life on Earth, improving this enzyme is one of the most promising avenues to help combat food insecurity. There has been heated debate as to whether there is scope to improve the enzyme; our new research provides a clear answer to this question. If evolution can improve rubisco, so can we!'
Senior author Professor Steven Kelly (Department of Biology, University of Oxford) said: 'We have shown that rubisco is not frozen in time but is instead continually evolving to get better. We now need to understand the factors that are holding rubisco back to enable us to realise its true potential.'
This new insight offers encouragement to efforts which aim to increase yields in food, fibre, and fuel crops by targeting rubisco engineering. Improving rubisco could be key to supporting the food needs of a growing global population.
Notes to editors
Interviews with Professor Steven Kelly are available on request: steven.kelly@biology.ox.ac.uk
The paper ‘Rubisco is evolving for improved catalytic efficiency and CO2 assimilation in plants’ has been published in PNAS: https://www.pnas.org/doi/10.1073/pnas.2321050121
About the University of Oxford
Oxford University has been placed number 1 in the Times Higher Education World University Rankings for the eighth year running, and number 3 in the QS World Rankings 2024. At the heart of this success are the twin-pillars of our ground-breaking research and innovation and our distinctive educational offer.
Oxford is world-famous for research and teaching excellence and home to some of the most talented people from across the globe. Our work helps the lives of millions, solving real-world problems through a huge network of partnerships and collaborations. The breadth and interdisciplinary nature of our research alongside our personalised approach to teaching sparks imaginative and inventive insights and solutions.
Through its research commercialisation arm, Oxford University Innovation, Oxford is the highest university patent filer in the UK and is ranked first in the UK for university spinouts, having created more than 300 new companies since 1988. Over a third of these companies have been created in the past five years. The university is a catalyst for prosperity in Oxfordshire and the United Kingdom, contributing £15.7 billion to the UK economy in 2018/19, and supports more than 28,000 full time jobs.
JOURNAL
Proceedings of the National Academy of Sciences
ARTICLE TITLE
The world’s most prolific CO2-fixing enzyme is slowly getting better
ARTICLE PUBLICATION DATE
5-Mar-2024
No comments:
Post a Comment