Dr. Burkey’s experience is in plant physiology biochemistry. Currently as a member of the USDA-ARS Plant Science Research Unit, Dr. Burkey conducts air pollution and climate change research to determine impacts of elevated ozone, carbon dioxide, and temperature on agricultural crops and natural vegetation.

Ozone Effects on Crop Production
Ozone is a toxic gas formed by reactions between oxygen in the atmosphere and the pollutants (nitrogen oxides and hydrocarbons) produced during the combustion of fossil fuels. Ozone exposure causes characteristic visible injury on the foliage of sensitive plants. Ground-level ozone concentrations are sufficiently high in agricultural regions to inhibit plant growth and reduce yields.

Identification of Ozone-tolerant Varieties
In all crops examined to date, genetic variation in ozone sensitivity has been observed. Yield loss can be reduced by use of tolerant varieties. Dr. Burkey and colleagues screen snap bean, soybean, and wheat cultivars for differences in ozone response to identify tolerant lines and to understand the genetics of tolerance.

Ozone Tolerance Mechanisms and Future Crop Improvement
Plant characteristics and associated genes that confer ozone tolerance are not known. This limits the ability to screen for tolerance and prevents the use of molecular approaches to develop new varieties. A major objective of Dr. Burkey’s program is to identify physiological and biochemical differences between ozone-sensitive and tolerant plants that account for the differences in ozone response. Current areas of investigation include stomatal limitation of ozone uptake, metabolism involved in the detoxification of ozone molecules that enter the leaf, and gene expression studies to indentify genes of interest that could be targeted to alter plant response to ozone. Collaborations with plant breeders are underway to transfer ozone tolerance traits into breeding lines for cultivar development. Recent findings suggest that traits limiting ozone uptake into leaves may also contribute to drought tolerance.

Plants as biological indicators of ambient ozone
Genotype differences in ozone sensitivity can be utilized as biological indicator systems for monitoring ambient ozone levels. Scientists in the USDA-ARS Plant Science Research Unit have developed a system based on biomass production by ozone-sensitive and tolerant clover clones. Dr. Burkey and colleagues have developed ozone-sensitive and tolerant snap beans as an alternative system. Plant bio-indicators are also valuable educational tools for increasing public awareness of air pollution problems. The snap bean system is currently used in the USA, Europe, and Asia to detect and quantify ozone impacts on plants across regions of contrasting climatic conditions.

Assessing heat stress in crops
The impact of heat stress in crop plants is a new area of research in Dr. Burkey’s program. Exposure technologies have been developed and deployed to provide season-long elevated temperature treatments in field plots. Studies are underway to characterize the interactive effects of elevated ozone and elevated temperature on crop growth and yield. A next phase will be screening germplasm to identify sources of heat stress tolerance.

Plant Science Research