Researcher(s)
- Zoe Yiournas-Kneipp, Agriculture and Natural Resources, University of Delaware
Faculty Mentor(s)
- Jesus Beltran, Plant and Soil Sciences, University of Delaware
Abstract
Background / Introduction
Limited space within high-density agricultural operations requires maximized yield systems in place. More than ever, we need to optimize area with dense planting rows that may affect light distribution, which has everything to do with leaf angles in plants. Leaf angle plays a pivotal role in plant architecture, having influences mainly on light interception, photosynthesis, and ultimately crop yield through its impact on the canopy structure and planting density. ABA is a well-known plant stress hormone that regulates growth and development, yet its specific role in modulating leaf angle currently remains vastly misunderstood—particularly widespread amongst different plant morphologies.
Objectives / Hypothesis
This study investigates exogenous ABA altercations to leaf angle via petiole cell expansion and whether this response is conserved across species with contrasting growth forms: Arabidopsis thaliana and Solanum lycopersicum (tomato).
Methods
Arabidopsis (Col-0 variety) and tomato (Moneymaker variety) plants were both grown under specific controlled-environment conditions. ABA was applied at varying concentrations (0 µM(control), 10 µM, 50 µM, 150 µM) administered through foliar spray in both species. Leaf angles were measured over a 48 hour period using an image-based analysis application known as Angle Meter. Leaf temperature, a valuable proxy for stomatal responses, was assessed using a thermography camera 2 hours post-treatment. A randomized complete block design was used, with 3 sets of 3 biological replicates across treatments was employed to ensure a substantial data set.
Results
Preliminary data suggests that ABA treatment resulted in measurable changes within leaf angle in both species, with more severe changes in higher dosages– the results were most pronounced at 50 µM and 150 µM of ABA. Phenotypically, the plant showed response to treatment by expanding its leaves to some capacity. Quantitatively, subjects showed an overall reduction in the angle within most cases after application. Although results were more prominent in tomato, the pattern and timing of leaf angle changes were broadly conserved between arabidopsis and tomato, suggesting a shared regulatory mechanism. Furthermore, elevated leaf temperatures measured through the thermal camera confirmed stomatal closure post-treatment in both subjects.
Conclusions / Significance
Ultimately, exogenous ABA has shown to modulate leaf angle changes in both arabidopsis and tomato, through measurable effects on petiole cell expansion and stomatal regulation. These findings indicate possible development in issuing ABA in leaf positioning across diverse plant structures, as well as in agricultural research methods. Understanding this mechanism could have implications for optimizing canopy design and improving light-use efficiency in crops under specific stress conditions.