Elevated carbon dioxide levels can lead to a lack of minerals in plants, leading to fewer nutritious crops

For years, scientists have viewed enhanced photosynthesis as one of the only possible benefits of increased levels of carbon dioxide in the atmosphere — because plants use carbon dioxide for photosynthesis, it can be expected that higher levels of carbon dioxide will lead to higher
plant yields.
In a Nov.
3 review published Nov.
3 in Trends in Plant Science, scientists at the Institute of Plant Science in Montpellier, France, explain why the effect may be smaller than expected, as elevated carbon dioxide levels make it difficult for plants to get the minerals they need to grow and provide nutritious food
.

Alain Gojon, research director and first author of the French National Institute of Agriculture, Food and Environment, said: "There are many reports in the literature that suggest that CO2 levels expected by the end of the 21st century will lead to lower concentrations of nitrogen in most plants, mainly affecting the protein content
in plant products.
" "It's important to
understand why growing plants in environments with elevated carbon dioxide concentrations has such a negative impact on the protein content of most staple crops and future food.
"

Plants use photosynthesis to convert carbon dioxide into sugar, which leads to energy
.
However, photosynthesis does not provide plants with the key minerals
they need to grow.
For most plants, these minerals, such as nitrogen, phosphorus, and iron, are absorbed from the soil through the
root system.
Nitrogen is especially important because it is a key component
of the amino acids that plants use to make proteins.

Nitrogen deficiency not only means that plant tissue is difficult to grow, but also means that it provides less
nutrients to humans.
"What is clear is that the nutritional content of major crops around the world, such as rice and wheat, has been negatively affected
by elevated carbon dioxide concentrations.
This will have a significant impact on food quality and global food security," said
corresponding author Antoine Martin, a researcher at the French National Centre for Scientific Research.

"Two main nutrients that are essential for human nutrition may be affected by this phenomenon," Gojon added
.
"The first is a protein
made of nitrogen.
This can be a big problem in developing countries, where many diets are low in protein and plants grown in environments with elevated carbon dioxide concentrations may contain 20 to 30 percent
less.
The second is iron
.
Iron deficiency is estimated to already affect 2 billion people
worldwide.
”

In addition to the global food system, a decrease in plant mineral content in the context of increased atmospheric CO2 levels could lead to a negative feedback loop
for climate change mitigation.
"If much of the vegetation is deficient in nitrogen and other minerals, terrestrial carbon sinks associated with enhanced photosynthesis may be constrained, which could prevent any additional increase
in carbon dioxide captured from the atmosphere," Gojon said.

"We wanted to really understand the mechanism
that causes elevated CO2 concentrations to negatively affect the mineral composition of plants," Martin said.
"For example, we are currently exploring the natural genetic variation behind these negative impacts, which can then be used to improve the nutritional value
of crops in the CO2 atmosphere in the future.
"

Journal Reference:

1. Alain Gojon, Océ ane Cassan, Liê n Bach, Laurence Lejay, Antoine Martin.
   The decline of plant mineral nutrition under rising CO2: physiological and molecular aspects of a bad deal.
   Trends in Plant Science, 2022; DOI: 10.
   1016/j.
   tplants.
   2022.
   09.
   002ccessed November 3, 2022).