Primary Faculty Mentor Name

Mary Tierney

Status

Undergraduate

Student College

College of Agriculture and Life Sciences

Program/Major

Biological Sciences, Integrated

Primary Research Category

Biological Sciences

Presentation Title

Is the retromer required for polarized cell growth in Brachypodium distachyon?

Time

3:00 PM

Location

Silver Maple Ballroom - Biological Sciences

Abstract

For a plant to develop and mature it must be able to easily obtain water and essential nutrients from its environment. The amount of nutrients and water available to a plant is related to its root surface area and thus plants use root hairs to increase the surface area of epidermal root cells. The specialized root cells that produce root hairs, known as trichoblasts, use polarized cell growth to extend the cell wall and plasma membrane of the root hair out into the soil. This process requires both secretion and endocytosis at the tip of the root hair. Crucial to this polarized growth is a protein complex known as the large subunit of the retromer. This large subunit is made up of 3 proteins, VPS35, VPS29 and VPS26, and is responsible for recycling membrane proteins to the Golgi or plasma membrane. In eudicots, the VPS26 gene family includes 3 proteins (VPS26A, B, and C), but only VPS26C plays a role in normal root hair growth in Arabidopsis thaliana (Jha et al. 2018). In contrast, monocots only contain two VPS26 gene family members, neither of which shares significant sequence homology to VPS26C in Arabidopsis. This raises the question of whether polarized cell growth is different in monocot and eudicot plants or whether one of the two VPS26 genes in monocots retains the same function as VPS26C in Arabidopsis. To test this experimentally, we are cloning the two VPS26 genes from the model grass species Brachypodium distachyon and transforming each of these into the Arabidopsis vps26c mutant to determine if one or both of these genes can complement the vps26c root hair phenotype in Arabidopsis. Whether or not the vps26c mutant phenotype will be complimented by one of the Brachypodium VPS26 genes will reveal important information about the inner mechanism(s) of polarized growth in both monocots and eudicots.

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Is the retromer required for polarized cell growth in Brachypodium distachyon?

For a plant to develop and mature it must be able to easily obtain water and essential nutrients from its environment. The amount of nutrients and water available to a plant is related to its root surface area and thus plants use root hairs to increase the surface area of epidermal root cells. The specialized root cells that produce root hairs, known as trichoblasts, use polarized cell growth to extend the cell wall and plasma membrane of the root hair out into the soil. This process requires both secretion and endocytosis at the tip of the root hair. Crucial to this polarized growth is a protein complex known as the large subunit of the retromer. This large subunit is made up of 3 proteins, VPS35, VPS29 and VPS26, and is responsible for recycling membrane proteins to the Golgi or plasma membrane. In eudicots, the VPS26 gene family includes 3 proteins (VPS26A, B, and C), but only VPS26C plays a role in normal root hair growth in Arabidopsis thaliana (Jha et al. 2018). In contrast, monocots only contain two VPS26 gene family members, neither of which shares significant sequence homology to VPS26C in Arabidopsis. This raises the question of whether polarized cell growth is different in monocot and eudicot plants or whether one of the two VPS26 genes in monocots retains the same function as VPS26C in Arabidopsis. To test this experimentally, we are cloning the two VPS26 genes from the model grass species Brachypodium distachyon and transforming each of these into the Arabidopsis vps26c mutant to determine if one or both of these genes can complement the vps26c root hair phenotype in Arabidopsis. Whether or not the vps26c mutant phenotype will be complimented by one of the Brachypodium VPS26 genes will reveal important information about the inner mechanism(s) of polarized growth in both monocots and eudicots.