Cells, Genes & Molecules

Short- and long-term responses to elevated carbon dioxide use the same genetic controls

Manipulating stomatal traits could produce more crops for dry regions.

For most plant species, elevated atmospheric CO2 levels lead to a decrease in stomatal conductance (gs) by causing the partial closure of the stomata. This allows the plant to decrease transpirational water loss. Current knowledge of the molecular-level control of stomatal CO2 response is based primarily on studies that investigated response to short-term CO2 changes, on the scale of minutes to hours. It’s unclear, however, whether this data is representative of longer-term changes occurring over weeks or months. With atmospheric CO2 levels projected to double over the next century, long-term stomatal response could have a major impact on plant water use in the future, and an understanding of its regulation could help researchers to improve crop water-use efficiency.

Photo by Eftodii Aurelia from Pexels

In a new study published in Annals of Botany, lead author Karin S.L. Johansson and colleagues studied the genetic controls of short- and long-term gs responses to elevated CO2 levels. The researchers used two arabidopsis recombinant inbred lines, one with a strong CO2 response, and one with a weak CO2 response, and employed quantitative trait locus (QTL) mapping to pinpoint loci controlling gs responses.

The authors found that short- and long-term stomatal responses were both associated with a QTL on chromosome 2 that explained about half of the short-term variation seen in responses between the weak and strong lines. Elevated CO2 caused an average gs decrease of 26% in the arabidopsis lines tested, which is similar to what has been found in field experiments studying long-term response. The plants also showed a 60% increase in total leaf area.

“The fact that short- and long-term CO2 responses were significantly correlated and associated with the same locus suggests that knowledge about the signalling pathway for short-term gs regulation in response to elevated CO2 concentration could be used for manipulation of long-term gs responses under rising atmospheric CO2,” write the authors. They note that breeding crops for high water-use efficiency could produce varieties able to grow in arid regions, as has already been accomplished with wheat. “Large differences in gs or water-use efficiency observed among cultivars of wheat, rice, maize, legumes, cotton, and sugarcane show that there is a large untapped potential in the genetic variation for stomatal traits in crop species as well.”