Similar photosynthetic but different yield responses of C3 and C4 crops to elevated O3

Authors: LI, SHUAI - University Of Illinois; LEAKEY, ANDREW - University Of Illinois; MOLLER, CHRISTOPHER - University Of Illinois; Montes, Christopher; SACKS, ERIK - University Of Illinois; LEE, D - University Of Illinois; Ainsworth, Elizabeth - Lisa

Submitted to: Proceedings of the National Academy of Sciences (PNAS)
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/6/2023
Publication Date: 11/10/2023
Citation: Li, S., Leakey, A.D.B., Moller, C., Montes, C.M., Sacks, E., Lee, D.K., Ainsworth, E.A. 2023. Similar photosynthetic but different yield responses of C3 and C4 crops to elevated O3. Proceedings of the National Academy of Sciences (PNAS). 120(46). Article e2313591120. https://doi.org/10.1073/pnas.2313591120.
DOI: https://doi.org/10.1073/pnas.2313591120

Interpretive Summary: Current ground-level ozone concentration ([O3]) significantly reduces global crop productivity. Understanding the response to O3 enrichment between crop types is critical to improve crop production and resilience under global change. In this paper, we quantitatively synthesize available literature and unpublished data from five C3 crops and four C4 crops across global O3-free air concentration enrichment facilities over the past 20 years. We quantitatively show that C3 crops are more sensitive to elevated [O3] than C4 crops. Our results provide key insights into O3 response in crops with different photosynthetic pathways and could help to guide future efforts to improve crop O3 tolerance.

Technical Abstract: The deleterious effects of ozone (O3) pollution on crop physiology, yield and productivity are widely acknowledged. It has also been assumed that C4 crops with a carbon concentrating mechanism and greater water use efficiency are less sensitive to O3 pollution than C3 crops. This assumption has not been widely tested. Therefore, we compiled 45 journal articles and unpublished datasets that reported leaf photosynthetic and biochemical traits, plant biomass, and yield in five C3 crops (chickpea, rice, snap bean, soybean, wheat) and four C4 crops (sorghum, maize, Miscanthus × giganteus, switchgrass) grown under ambient and elevated O3 concentration ([O3]) in the field at free-air O3 concentration enrichment (O3-FACE) facilities over the past 20 years. When normalized by O3 exposure, C3 and C4 crops showed a similar response of leaf photosynthesis, but the reduction in chlorophyll content, fluorescence and yield was greater in C3 crops compared with C4 crops. Additionally, inbred and hybrid lines of rice and maize showed different sensitivities to O3 exposure. This study quantitatively demonstrates that C4 crops respond less to elevated [O3] than C3 crops. This understanding could help maintain cropland productivity in an increasingly polluted atmosphere.