PI: Elizabeth Ainsworth (UIUC)
Co-PIs: Andrew Leakey (UIUC), Patrick Brown (UIUC), Lauren McIntyre (University of Florida)

Funding Source: NSF Plant Genome Program ($5.7 million) NSF PGR-1238030

Project website: http://www.maizeo3face.illinois.edu/

Project twitter feed: @amaizeingO3

INTELLECTUAL MERIT

Tropospheric ozone (O3) is the most damaging air pollutant to crops. Today, oxidative stress arising from O3 exposure is reducing potential maize yields by up to 10%, which in 2011 would have been valued at $7646 million. Yield losses to O3 are projected to as much as double by mid-century, and there is little potential for adaptation to rising O3 concentrations ([O3]) through altered crop management practices. Therefore, the only solution to current and future O3-induced yield loss is development of O3 tolerant maize through breeding and/or biotechnology. Elucidating the genomic basis for O3 tolerance in maize has broad implications for understanding of oxidative stress and signaling due to cross talk between gene networks responsive to O3, abiotic stress and biotic stress. The availability of genomic and genetic tools for maize make it an ideal model in which to explore oxidative stress in C4 species, a group whose response to oxidative stress is poorly understood relative to its enormous importance for agricultural food and fuel production as well as natural ecosystem function.

This project couples the unique capabilities of Free Air Concentration Enrichment (FACE) technology, which provides controlled elevation of [O3] in open-air at field scale, with the power of the vast genetic resources in maize and RNA-Seq. It will provide a foundation for crop improvement by (i) quantifying genetic variation in response to elevated [O3] among 200 inbred and 100 hybrid maize lines in the field; (ii) using high-throughput phenotyping of O3 impacts on maize growth, senescence, leaf metabolism and reproductive processes, to identify traits that correlate with yield loss; (iii) identifying the genes and gene networks underpinning the O3 response in the most extreme tolerant and susceptible lines, and their hybrids, by integrating RNA-seq expression analysis and detailed physiological analysis in inbred and hybrid maize; (iv) developing, or identifying existing, biparental populations derived from tolerant and sensitive parents to identify QTLs and eQTLs for O3 tolerance; and (v) assessing crosstalk between O3 and biotic stress response gene networks in maize. This work will address key mechanistic hypotheses about how oxidative stress leads to transcriptional reprogramming of antioxidant and carbon metabolism, as well as hormone, senescence and defense pathways – integrating the role of tissue specific responses in the stomatal complex, bundle sheath, mesophyll, pollen and silks. This multifaceted approach is essential because multiple physiological drivers of yield are sensitive to oxidative stress from O3 exposure. Consequently, oxidative stress tolerance is undoubtedly a complex, polygenic trait. But, the broad application of quantitative genetic tools coupled to RNA-seq expression profiling, biochemical and physiological analyses of diverse germplasm makes the challenge of discovering the foundation for O3 tolerance tractable for the first time.

BROADER IMPACTS

This project will provide genomic training to two mid-career plant physiologists with expertise in studying plant physiological and agronomic responses to environmental change, along with a team of post-docs and graduate students. This will allow them to address major challenges in agriculture and ecology by leveraging the full power of genomics through bioinformatics, quantitative genetics and expression profiling using next-generation sequencing technologies. This will immediately transform the focus of research at the internationally renowned SoyFACE facility away from impact assessment and towards development of “climate-proof” crops. Cross-fertilization of training and knowledge with projects in Brazil, Philippines and Panama will advance efforts to predict future rain forest carbon cycling and adapt crops to environmental change in regions of the world where food security is most at risk. Recruitment of school-age children into plant genomics will be promoted through a face-to-face and on-line after school project (Plants iView) and a summer science camp for high school girls on high-throughput imaging of pollen viability. Retaining students interested in plant genomics will be supported by mentoring of undergraduate and graduate students as they participate in the research project.