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ISU alum and molecular biologist Christy Fornero will present research on plant cell walls, October 15

close-up image of plant hair

Plat hair

Christy Fornero, M.S. ’15, will give a presentation on roles of microtubule cytoskeleton in cell wall division in the plant, Arabidopsis thaliana. She will also present her research on the development of plant hairs. Her seminar will take place at 4 p.m. Tuesday, October 15, in Moulton Hall, room 210. Everyone is welcome to attend.

Fornero went to Arcadia University in Pennsylvania for her undergraduate studies, where she received her bachelor’s degree in biology. She received her master’s degree from Illinois State before continuing on as a Ph.D. student in Viktor Kirik’s lab. She studied proteins important for cell division and cell wall development in the model plant Arabidopsis thaliana. Her talk will feature results gathered for two of the research projects conducted during her time here at ISU.

Her seminar presentation title is “Regulation of the microtubule cytoskeleton and cell wall development in Arabidopsis thaliana.

Below is her abstract:
Regulation of the cortical microtubule cytoskeleton is critical for organized plant cell division. Arabidopsis ton1 and ton2mutants display random cell division plane placement and lack the plant-specific cortical microtubule array that encircles the nucleus prior to mitosis In wild type plants, this preprophase band (PPB) of cortical microtubules precisely marks the future division plane. The specific roles of TON1 and TON2 in PPB formation are not yet known. It is suspected that TON1 Recruiting Motif (TRM) proteins may be involved in TON1 and TON2 recruitment to the PPB. Yeast-two-hybrid assays indicate that TRMs 1, 12, 13, 14, and 15 interact with TON1. TRM1 has been previously shown to target TON1 to microtubules, and BLAST analysis has revealed that TRMs 12, 13, 14, 15, 18, and 33, have homology to phosphatidylinositol n-acetylglucosaminyltransferase subunit Ps (PIGPs). PIGs are involved in the synthesis of glycosyl phosphatidylinositol (GPI) anchors, which are posttranslational modifications that attach the modified proteins in the outer leaflet of the plasma membrane. Targeted disruption of these PIG-P like TRMs, along with localization studies of a larger subset of TRMs, were conducted in an effort to shed light on the mechanisms responsible for PPB formation. We found that TRM33 localizes to the PPB, indicating that it may be important for plant cell division. In addition, TRM13 and TRM14 were found to be important for leaf morphogenesis and trichome cell polarity. Together, these results indicate diverse roles for TRMs in the regulation of the microtubule cytoskeleton and plant development.

The plant cell wall plays an important role in communication, defense, organization, and support. The importance of each of these functions varies by cell type, with specialized cells, such as Arabidopsis trichomes, or leaf hairs, exhibiting distinct cell wall characteristics, including papillae. To better understand the molecular processes important for papillae deposition on the cell wall surface, we identified the GLASSY HAIR 1 (GLH1) and GLASSY HAIR 2 (GLH2) genes, which are necessary for papillae formation. We found that a splice-site mutation in the component of the transcriptional Mediator complex MED25 gene is responsible for the papillae-less phenotype of the glh1 mutant. Elemental analysis indicates that calcium ion accumulation in trichomes is strongly reduced in glh1 mutants, suggesting that the processes important for papillae deposition may also be important for calcium deposition at the trichome cell wall surface. Fortuitously, the glh2 mutation was mapped to a gene encoding the Mediator complex subunit MED16. A GFP-MED16 fusion was shown to localize to the nucleus, consistent with a role in transcriptional regulation. The MED25 and MED16 genes are expressed in trichomes. The expression of the trichome development marker genes GLABRA2 (GL2) and Ethylene Receptor2 (ETR2) is not affected in the glh1 or glh2 mutants. A screen of additional Mediator tail subunit mutants revealed that med2, med14, and med15a also exhibit a glassy trichome phenotype. Collectively, the presented results show that MED25 and MED16 are necessary for papillae formation on the cell wall surface of leaf trichomes and that a subset of Arabidopsis Mediator tail subunits is required for the transcriptional regulation of papillae promoting genes.

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