Discipline: Ecology Environmental and Earth Sciences
Madalyn Bryant - Fort Valley State University
Co-Author(s): Sarathi Weraduwage and Thomas Sharkey, Michigan State University, East Lansing, MI
Studies have shown that a ubiquitin conjugating enzyme (UBC22) is present in peroxisomes of plants and may act as a negative regulator during the conversion of indole butyric acid to indole acetic acid (IAA). IAA is an auxin and is known to inhibit primary root elongation, induce lateral root formation, promote stem elongation, inhibit growth of lateral buds, and regulate plant responses to light and gravity.
Two UBC22 gene knockout mutants (ubc22-1 and ubc22-2) of Arabidopsis thaliana were used to investigate the impact of removing the negative regulation of UBC22 on leaf gas exchange, carbon partitioning, and plant growth. It was hypothesized that the mutant lines will show altered plant growth in comparison to the wild-type.
A comprehensive growth analysis was carried out to measure leaf area, root and stem length, growth rates, and dry weights throughout the growth cycle. Photosynthesis and respiration rates were measured to determine net carbon gain. Leaf anatomy and thickness measurements were taken to examine leaf cell density and mesophyll structure. Chlorophyll content and total protein extraction and quantification were also carried out.
The role of UBC22 in regulating auxin biosynthesis and subsequently carbon assimilation, and growth were measured throughout the vegetative stages of the plants. Suppressing the ubiquitin conjugating enzyme gene positively affects plant growth as well as whole plant photosynthesis.
Funder Acknowledgement(s): This study was supported, in part, by NSF HRD HBCU-UP Targeted (Award # 1238789), NSF REU Site: Plant Genomics @ MSU (Award # DBI-1358474), and Plant Research Laboratory - U.S. Department of Energy (Award # DE-FG02-91ER20021).
Faculty Advisor: Sarwan Dhir,