Adapting C₄ Photosynthesis to Atmospheric Change and Increasing Productivity by Elevating Rubisco Content in Sorghum and Sugarcane

Authors

• Coralie E. Salesse-Smith, University of Illinois at Urbana-ChampaignFollow
• Noga Adar, University of Illinois at Urbana-Champaign
• Baskaran Kannan, University of Florida
• Thaibinhduong Nguyen, University of Florida
• Wei Wei, University of Illinois at Urbana-Champaign
• Ming Guo, University of Nebraska-Lincoln
• Zhengxiang Ge, University of Nebraska-Lincoln
• Fredy Altpeter, University of Florida
• Tom E. Clemente, University of Nebraska-Lincoln
• Stephen P. Long, University of Illinois at Urbana ChampaignFollow

ORCID IDs

Salesse-Smith: https://orcid.org/0000-0002-2856-4217

Kannan: https://orcid.org/0000-0003-3082-9963

Wei: https://orcid.org/0000-0002-1337-5253

Guo: https://orcid.org/0000-0001-5338-9353

Altpeter: https://orcid.org/0000-0002-0894-4976

Long: https://orcid.org/0000-0002-8501-7164

Document Type

Article

Date of this Version

2025

Citation

Proceedings of the National Academy of Sciences (PNAS) (2025) 122(8): e2419943122

doi: 10.1073/pnas.2419943122

Comments

Open access

License: CC BY 4.0

Abstract

Meta-analyses and theory show that with rising atmospheric [CO2], Rubisco has become the greatest limitation to light-saturated leaf CO2 assimilation rates (A_sat) in C4 crops. So would transgenically increasing Rubisco increase A_sat and result in increased productivity in the field? Here, we successfully overexpressed the Rubisco small subunit (RbcS) with Rubisco accumulation factor 1 (Raf1) in both sorghum and sugarcane, resulting in significant increases in Rubisco content of 13 to 25% and up to 90% respectively. A_sat increased 12 to 15% and Rubisco enzyme activity ~40% in three independent transgenic events of both species. Sorghum plants also showed increased speeds of photosynthetic induction and decreased bundle sheath leakiness. These improvements translated into average increases of 15.5% in biomass in field-grown sorghum and a 37 to 81% increase in greenhouse-grown sugarcane. This suggests a potential opportunity to achieve substantial increases in productivity of this key economically important clade of C₄ crops, future proofing their value under global atmospheric change.