Day in, day out: Targeting the daily magnesium "rhythm" can optimize crop yield

July 10, 2020

The fundamental process that arguably forms the backbone of life on earth is photosynthesis; every organism is directly or indirectly dependent on this process. On paper, the process is simple: plants (and other organisms that have "chloroplasts," the structures where photosynthesis takes place, and give the characteristic green color to leaves) convert solar energy into chemical energy that helps them grow and flourish, and other "higher" organisms depend on these plants, or on organisms that feed on these plants, for their own sustenance, and so on.

But in practice, and especially at this point in biological history, this process is not so straightforward. The human population is growing at an unprecedented rate; the resources we have are not enough to feed the billions of people on earth today. While policymakers and politicians are trying to optimize the use of existing resources, scientists are doing their bit by figuring out how to improve the resources by exploring whether the natural process of photosynthesis can be modified through the latest technologies to ultimately improve the yield of food crops.

A team of scientists led by Prof Jian Feng Ma from Okayama University, Japan, and Prof Zhichang Chen from Fujian A & F University, China, also set out to explore photosynthesis, but they decided to do this with a twist: while current research predominantly focuses on trying to modify the direct chemical reactions involved in photosynthesis, the team decided to look at the "diel" variations--or the variations that occur over a periodic cycle of 24 hours--in photosynthesis.

That many processes of photosynthesis exhibit 24-hour variations shouldn't come as a surprise, given that the entire process is dependent on sunlight. Apart from external light-dark conditions, these diel changes can also be driven by internal genetic mechanisms.

But what exactly did these scientists look at? "Our study focused on magnesium, and for a diverse set of reasons," explains Prof Ma. "Magnesium is an essential macronutrient for plants, but around 15-35% of total magnesium intake is allocated to chloroplasts, where it functions not only as a structural element of chlorophyll but also as an activator for a number of photosynthetic enzymes." This meant that studying the diel changes in magnesium can shed light on an important functional aspect, and potential target for manipulation, of photosynthesis.

Through gene studies in the rice plant (the results of which are published in Nature Plants), the researchers decided to narrow in on a magnesium ion transporter OsMGT3, found in chloroplasts, and are known to be rhythmically expressed in "mesophyll" cells, the cells specialized for photosynthesis.

They created genetically modified rice plants in which the gene that gives rise to OsMGT3 was absent; they found that these plants showed significantly reduced uptake of magnesium and reduced amplitude of free magnesium ion fluctuations in chloroplasts. This resulted in a decrease in the activity of "ribulose 1,5-bisphosphate carboxylase," a fundamental enzyme of photosynthesis, naturally leading to a decline in the photosynthetic rate. Next, through genetic engineering techniques, they caused the excessive production of OsMGT3 in mesophyll cells in normal rice plants and found that the photosynthetic efficiency and growth improved in these plants.

These experiments proved that OsMGT3 partially controls the magnesium fluctuations in chloroplasts, and that these fluctuations may contribute to magnesium-dependent enzyme activities for photosynthesis over the daily cycle.

So where does this leave us in terms of optimizing crop yield and feeding the masses? Prof Ma states that the findings open up hitherto unexplored avenues, remarking, "Our studies put magnesium in the limelight. Modifying the magnesium input into chloroplasts could be a potential approach to improving photosynthetic efficiency in plants and can eventually improve crop yield."

This study, along with future studies that would demonstrate how exactly magnesium should be targeted, could be a potential answer to the global food shortage.
-end-


Okayama University

Related Photosynthesis Articles from Brightsurf:

During COVID, scientists turn to computers to understand C4 photosynthesis
When COVID closed down their lab, a team from the University of Essex turned to computational approaches to understand what makes some plants better adapted to transform light and carbon dioxide into yield through photosynthesis.

E. coli bacteria offer path to improving photosynthesis
Cornell University scientists have engineered a key plant enzyme and introduced it in Escherichia coli bacteria in order to create an optimal experimental environment for studying how to speed up photosynthesis, a holy grail for improving crop yields.

Showtime for photosynthesis
Using a unique combination of nanoscale imaging and chemical analysis, an international team of researchers has revealed a key step in the molecular mechanism behind the water splitting reaction of photosynthesis, a finding that could help inform the design of renewable energy technology.

Photosynthesis in a droplet
Researchers develop an artificial chloroplast.

Even bacteria need their space: Squished cells may shut down photosynthesis
Introverts take heart: When cells, like some people, get too squished, they can go into defense mode, even shutting down photosynthesis.

Marine cyanobacteria do not survive solely on photosynthesis
The University of Cordoba published a study in a journal from the Nature group that supports the idea that marine cyanobacteria also incorporate organic compounds from the environment.

Photosynthesis -- living laboratories
Ludwig-Maximilians-Universitaet (LMU) in Munich biologists Marcel Dann and Dario Leister have demonstrated for the first time that cyanobacteria and plants employ similar mechanisms and key proteins to regulate cyclic electron flow during photosynthesis.

Photosynthesis seen in a new light by rapid X-ray pulses
In a new study, led by Petra Fromme and Nadia Zatsepin at the Biodesign Center for Applied Structural Discovery, the School of Molecular Sciences and the Department of Physics at ASU, researchers investigated the structure of Photosystem I (PSI) with ultrashort X-ray pulses at the European X-ray Free Electron Laser (EuXFEL), located in Hamburg, Germany.

Photosynthesis olympics: can the best wheat varieties be even better?
Scientists have put elite wheat varieties through a sort of 'Photosynthesis Olympics' to find which varieties have the best performing photosynthesis.

Strange bacteria hint at ancient origin of photosynthesis
Structures inside rare bacteria are similar to those that power photosynthesis in plants today, suggesting the process is older than assumed.

Read More: Photosynthesis News and Photosynthesis Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.