Growing plants bigger isn’t necessarily better

As a response to higher amounts of carbon in the atmosphere, plants grow faster and bigger. This change in growth also shows a loss in the plant’s nutritional value. Researchers from Michigan State University have found that phosphorus might be a key to maintaining nutrition along with greater growth.

“We can’t synthesize [phosphorus] like we can nitrogen,” said Hatem Rouached, an assistant professor in the College of Agriculture and Natural Resources. “We need to develop a better understanding of how plants regulate phosphorus to survive.” 

Rouached and other researchers noticed that as plants exposed to carbon dioxide grow larger, their phosphorus content declines and they wondered why.

“We wanted to know why the plants weren’t taking up more phosphorus,” said Rouached. “And to see if the decrease of phosphorus levels is a defect or adaptive response, and whether there was a way to change that to ensure the plants grow and provide nutritious food too.” 

Looking inside of plant cells, the scientists discovered that not overloading chloroplasts (where photosynthesis takes place) with phosphorus was an adaptive measure. Phosphorus as part of photosynthesis is an important part of creating energy for a plant.   

“What was really important in our discovery is that when we try to force the plant to put a lot of phosphorus in the chloroplast, the plant failed to grow,” said Rouached. “We discovered that the increase in phytic acid levels needs to be tightly controlled in plants to allow the plants to grow under elevated carbon dioxide.” 

The cessation of plant growth with an increase in phytic acid has important implications for agriculture and nutrition, especially as carbon in the atmosphere continues to increase. There’s still much left for scientists to explore on the topic though.  

“This paper is the first to show there is an urgent need for discussion of how we can protect plant malnutrition against the increase of carbon dioxide worldwide,” said Rouached. 

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By Erin Moody , Earth.com Staff Writer