Naveen Chana will be giving her Undergraduate Honors Thesis defense on April 20th, 2023 at 1:30 p.m. in Biology Bldg. 123 (Lieber Room).
Title: AUG8 function in the Arabidopsis interphase cortical microtubule array
Abstract: The mechanisms controlling cellular morphogenesis are of particular importance in plants, which adapt to changing environmental stimuli through irreversible cell growth. Plant cell shape is defined by a semi-rigid cellulosic cell wall. Cellulose deposition is guided by a plasma-membrane associated network of microtubules nucleated by γ-tubulin ring complexes. This cortical microtubule array organizes into specific patterns in response to developmental and environmental cues that, in turn, pattern the cellulose deposition to influence how the walls extend to create cell shape. Thus, studying the mechanisms regulating cortical array organization is integral to elucidating how cellular morphogenesis occurs.
The hetero-octameric AUGMIN protein complex facilitates branching microtubule-dependent microtubule nucleation by connecting γ-tubulin ring complexes to pre-existing microtubules. In flowering plants, the AUGMIN complex’s microtubule-binding subunit, AUGMIN8 (AUG8), is one of nine paralogous genes. Specific AUG8 family members associate with the AUGMIN complex in a cell-cycle- or cell-type- specific manner. We hypothesize that different AUG8 paralogs could be key to defining different microtubule array patterns critical for specifying cell shape.
To test our hypothesis, we identified Arabidopsis mutants for AUG8 and its nearly identical paralogue, QWRF4, and characterized axial growth defects in the seedling hypocotyl. Data will be presented for defining the AUG8 and QWRF4 microtubule binding site using transiently expressed fluorescent protein fusions in Nicotiana benthamiana.