P-417 - Maize-pathogen interactions in elevated carbon dioxide

Wednesday, July 16, 2025

13:30 - 15:15

Location: Confex Hall 3

Plant Regulation of biotic and abiotic stress – trade-offs

Presenting Author(s)

EK

Ekkachai Khwanbua

Graduate student
Department of Plant Pathology, Entomology and Microbiology, Iowa State University
Ames, Iowa, United States

Author(s)

JS

John Ssengo

Graduate Student
Department of Plant Pathology, Entomology and Microbiology, Iowa State University, Ames, IA, USA
Ames, Iowa, United States
YQ

Yunhui Qi

Department of Data Science, Dana-Farber Cancer Institute
Boston, Massachusetts, United States
PL

Peng Liu

Department of Statistics, Iowa State University
Ames, Iowa, United States
MG

Michelle Graham

United States Department of Agriculture (USDA), Agricultural Research Service (ARS), Corn Insects and Crop Genetics Research Unit and Department of Agronomy
Ames, Iowa, United States
SW

Steven A. Whitham

Department of Plant Pathology, Entomology and Microbiology, Iowa State University
Ames, Iowa, United States

Rising atmospheric CO2 has profound implications for plant productivity and global food security. Atmospheric CO2 levels are on track to reach 550 parts per million (ppm) or more between 2050 and 2100. In this study, we investigated the impacts of current ambient CO2 (aCO2, 420 ppm) and elevated CO2 (eCO2, 550 ppm) on maize (Zea mays) physiology, immune responses, and susceptibility to diverse pathogens. Maize plants infected with Clavibacter nebraskensis under eCO2 showed slower symptom onset, smaller lesions, and reduced bacterial proliferation relative to aCO2. In contrast, susceptibility to sugarcane mosaic virus (SCMV) was enhanced at eCO2, with higher viral titers, greater disease progression, and a larger reduction in dry weight. For Puccinia sorghi, mean pustule size was larger at eCO2, although overall rust coverage, pustule number, and rust accumulation were similar. In addition, maize susceptibility to Exserohilum turcicum and Colletotrichum graminicola was decreased under eCO2, while susceptibility to the soil‐borne oomycete Pythium sylvaticum was unchanged. Transcriptomic analyses on plants inoculated with C. nebraskensis, SCMV, and P. sorghi were performed to further elucidate how eCO2 modulates these maize-pathogen interactions. Together, this work lays the foundation for future studies on the molecular mechanisms of maize defense under eCO2, while pinpointing pathogens of potential concern in future atmospheric scenarios.