CAREER: Roles of Organ Boundaries in Arabidopsis Abscission

University Of Mississippi, University MS

Investigators

Abstract

Plants must be able to release or drop various organs, such as leaves, flowers, fruits and seeds, at specific developmental stages or in response to environmental signals. This process is called abscission and relies on specialized cells within abscission zones. Over the past decade, research using the model plant Arabidopsis has revealed multiple components that regulate the programmed loss of cell-to-cell adhesion in organ abscission zones. However, little is currently known about the mechanisms that determine where abscission zones are located or what genes are necessary for their development. In Arabidopsis flowers, abscission zones form at boundary regions between the floral organs and underlying stem. The focus of this research is to investigate whether a subset of the genes known to control the position and development of organ boundaries subsequently direct the formation of organ abscission zones. Advances made in understanding the basis of abscission zone development may lead to novel technologies to modify organ abscission in crop plants. The ability to induce organ abscission would enhance fruit thinning and facilitate mechanical harvest, while inhibition of abscission would prevent premature flower or fruit drop and improve postharvest quality. The educational activities of this project will provide advanced training in genetics for University of Mississippi undergraduates and research opportunities for individuals preparing for graduate education in STEM fields. Increased genetic literacy is vital for preparing future health-care professionals and citizens alike to understand the rapid advances underway in medical diagnostics, gene therapy and personalized medicine. Although key signaling pathways that activate and inhibit organ abscission have been outlined in Arabidopsis, the progression of events underlying abscission zone differentiation remains poorly understood. Accumulating evidence suggests that abscission zone placement is influenced by the formation of lateral organ as well as inter-organ boundaries. The goal of the proposed research is to evaluate how the gene networks that pattern organ boundaries in leaves, flowers and fruit contribute to abscission zone positioning and specification. Mutants that perturb the definition of the sepal-receptacle boundary and displace organ abscission zones will be used as tools to investigate the hypothesized roles of selected organ boundary genes. Phenotypes of mutants with organ boundary and abscission zone defects will be assessed using scanning electron microscopy, histological analysis and molecular markers of organ boundary and abscission zone cells. An expected outcome of these studies is the identification of candidate transcriptional regulators of abscission zone-specific signaling molecules. Genetics education for University of Mississippi undergraduates will be enhanced by introducing an Honors Genetics course, engaging Honors students in the PI's organ boundary experiments and designing new Genetics laboratory modules. To provide training opportunities to individuals with diverse educational backgrounds, the PI?s laboratory will host multiple post-baccalaureate and undergraduate research interns during the funding period. The PI has an established track record of mentoring young scientists, many of whom are women and/or individuals from ethnic backgrounds underrepresented in science.