Undergraduate Student University of North Alabama Trafford, Alabama
Body of Abstract: Light quality is essential for crop health. In a crowded crop field, sunlight availability for photosynthesis is limited. Plants selectively use red light (λ = 660 nm) for photosynthesis relative to far-red light (λ = 730 nm). As more red light is consumed, more far-red light is available resulting in a lower ratio of red to far-red light (R:FR). Plants compete with each other for sunlight through the shade avoidance response. Under low R:FR, the shade avoidance response can increase hypocotyl and petiole length as well as leaf elevation angles for better access to sunlight. The plant stress hormone abscisic acid (ABA) has also been found to affect similar responses. However, not many studies have been conducted to study the interactions between light quality and ABA in this context. In this study, we report the effect of exogenous ABA on leaf elevation angles during the shade avoidance response in Arabidopsis thaliana. We used a new computational approach to measure the dynamics of leaf elevation angles over time. Time-lapse images were acquired with Raspberry Pi microcomputers. The leaf elevation index (angle) for each plant was determined by analyzing the images using an image analysis software package called PlantCV. Our results indicated that the increased leaf elevation angles upon low R:FR treatment were less pronounced when exogenous ABA was applied, whereas the leaf elevation angles under high R:FR conditions were not affected significantly by exogenous ABA. This work suggests that environmental stress can interfere with plant responses to light conditions. Further studies on such signal interactions will help improve agricultural productivity under changing environmental conditions.