Presenter: Valeria Lacouture

Faculty Sponsor: Samuel P. Hazen

School: UMass Amherst

Research Area: Biology

Session: Poster Session 5, 3:15 PM - 4:00 PM, 163, C15

ABSTRACT

Plant growth proceeds through stages of cell division, elongation, and secondary cell wall synthesis. The plant hormone auxin functions as a key developmental regulator that can either delay or promote secondary cell wall deposition depending on cellular context. Although auxin is known to regulate many aspects of plant development through controlled synthesis, transport, and signaling, its specific role in secondary cell wall formation in grasses remains poorly understood. To address this gap, we investigated auxin-responsive expression of CELLULOSE SYNTHASE 8 (CESA8), a gene required for wall thickening, in the model grass Brachypodium distachyon. We used a bioluminescent CESA8pro:LUC reporter to monitor gene expression in living plants. Seedlings were treated with auxin as indole-3-acetic acid (IAA), the auxin signaling inhibitor p-chlorophenoxyisobutyric acid (PCIB), or a mock control and imaged over a 48-hour time course. Luminescence was quantified separately in stem and root tissues. Auxin treatment had little effect on CESA8pro:LUC expression in stem tissue but caused a significant decrease in expression in roots. These results indicate that auxin regulates secondary cell wall gene expression in a tissue-specific manner in B. distachyon, acting as a negative regulator in roots while having limited effects in stems under these conditions. This work improves our understanding of how auxin regulates developmental transitions associated with secondary cell wall formation in grasses and provides insight into hormone-mediated control of plant growth.