Date of Award


Document Type


Degree Name

Master of Science (MS)


School of Biological Sciences

First Advisor

Viktor Kirik


Microtubules carry out many functions within the cell. They're used during mitosis and meiosis to move chromosomes to opposite sides of the cell so that cell division can occur. They're also used as structural support for the cell and are involved in establishing the cell shape. Microtubules are also able to reorient from a longitudinal orientation to a transverse orientation in response to gibberellic acid and auxin (two hormones that are involved in cell elongation). The mechanism for how this reorientation occurs is unknown. The TONNEAU2 (TON2) protein is necessary for proper microtubule organization. We looked at how TON2 affects microtubule orientation and nucleation in response to the hormones gibberellic acid and auxin and found that while the ton2 mutant can reorient in response to the hormones it is less efficient. We also found that nucleation mode is not causing the reorientation. Previously it was found that TON2 interacts with the POK protein. POK is a protein that interacts with the phragmoplast and helps orient it for proper formation of the cell plate. We looked at POK localization and timing in ton2 mutants, which lack a PPB. POK's presence overlapped with the cell cycle stages that TON2 is present during and localized to the same place the PPB used to inhabit. RIC1 is another putative TON2 interacting protein. We tested the genetic relationship between RIC1 and TON2 in cell shape determination. Our data shows that TON2 could be epistatic to RIC1 by comparing the neck and lobe lengths of pavement cells in wild type, ric1-1 mutants, ton2 mutants, and ric1-1 ton2 double mutants, but more data is needed to confirm this hypothesis. The double mutant had the same phenotype of no or few and small lobes as the ton2 mutant.


Imported from ProQuest Atkinson_ilstu_0092N_10373.pdf


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