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Amy Burton

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102 Tyson Building

Penn State University

University Park, PA 16802

(814) 863-6139 fax

ALB425 @ psu.edu

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RESEARCH OVERVIEW

My research deals with high throughput phenotypic screening of root anatomical and morphological traits with putative agronomic value. Much of my work is focused on the formation of aerenchyma in the roots of maize (Zea mays), and the role of this tissue in below-ground resource acquisition efficiency in crop plants. I use a combined approach of morphological and architectural measurement, histology and semi-automated image analysis.

Any plant trait may be measured, but its agronomic importance can be assessed by the impact of its variation on performance and yield. Acceptable thresholds for yield and its stability may be hard to broadly delineate, given constitutive variation between genotypes, or plastic responses to differences in edaphic or other environmental factors. Additionally, concepts such as vigor and performance may be difficult to define, further complicating breeding efforts. The role of phenotype screening in breeding programs is to identify complex combinations of traits that collectively hold agronomic value.

Phenotypic screening is a way to characterize plant traits, with the intent of quantifying their expression. A primary challenge of this work is to distill complex plant processes into their constituent traits, and then to determine which of those traits might most profoundly shape large-scale processes. Furthermore, phenotyping must include the best ways to accurately measure traits, and efficient methods to scale up to significant sample sizes.

Root traits represent a particularly underutilized area in breeding, though the root system’s role as a major resource-acquiring unit clearly cannot be overlooked. Root anatomical traits are directly related to acquisition and transport of resources from the soil, and may influence stress response, or be shaped by environmental factors. The ability to make accurate, rapid and reliable measurements of anatomical traits could lead to the potential use of a given trait in breeding.

Of all the various combinations of traits, no single root system is perfectly suited to efficiently obtain every necessary soil resource. Root system growth is both strategic and dynamic, being composed of traits whose value may change with growth, introduction of new root classes, or other ontogenic events. Evaluation of a phenotype can be further confused by the fact that trait expression may be constitutive or plastic. The adaptive significance of a characteristic can be affected by temporal and spatial aspects of its surroundings. Overall, soil resource acquisition is a function of assorted traits working in concert within a given environment.

Since food crops are grown in diverse ecosystems, identification of traits related to environmental plasticity are of tremendous interest to plant breeders working with such crops. Traits associated with efficient nutrient uptake have the potential to preserve environmental integrity in ecosystems bordering agricultural lands, as well as reducing fertilizer costs in areas where high input agriculture is not economically feasible. As one of the earliest domesticated crops, the natural genetic variation in the Zea species is vast, and such variation has allowed this taxon to thrive in many climates and soil types across the world. Understanding the natural adaptations of an important food source, such as maize, could lead to increased performance and yields in cropping systems in which edaphic and economic resources are not ideal.