Regulation of multiple developmental processes by AtFH1 and AtARP3 mediated actin cytoskeleton in Arabidopsis thaliana
Date
2018-05-31
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
Type
Thesis
Degree Level
Masters
Abstract
The actin cytoskeleton plays a multifaceted role in plant biology. It is involved in several
developmental processes and is needed to cope with both biotic and abiotic stresses. Actin is a
highly conserved, the most abundant and multifunctional globular protein that can exist either as
a globular sub-unit (G-actin) or filamentous (F-actin) form. F-actin is the microfilament part of the
cytoskeleton polymerized from G-actin. Actin cytoskeleton polymerization is facilitated by several
proteins like formins (polymerizing linear actin cytoskeletons) and the ARP2/3 complex
(polymerizing branched actin cytoskeletons). AtFH1 and AtARP3 are important regulators of actin
cytoskeleton in Arabidopsis thaliana and belong to the formins and ARP2/3 complex,
respectively. The effect of AtFH1 and AtARP3 on actin cytoskeleton reorganization and its
subsequent regulation on multiple developmental processes in Arabidopsis thaliana were studied
using both single and double mutants of these genes. Simultaneous mutation of AtFH1 and
AtARP3 appears to have a lethal effect. Although fh1-1 was not a true knockout mutant, the double
mutant fh1-1/arp3-1 further recovered some expression of the AtFH1 gene compared to fh1-1
single mutant but a homozygous double mutant was not obtained. This double mutant showed
several unique characteristics compared to the wild type and each single mutant, such as small
plants with short, narrow and pale green leaves; short root, slow root growth rate; greater
gravitropic response; altered lateral root locations etc. At the cellular level, the double mutant
exhibited deformities in epidermal cell circularity; short root hairs; distinct trichome phenotype;
small mesophyll cells with lower chloroplasts content; small pollen size, a number of which were
structurally distorted. The double mutant produced tiny flowers with distinct floral organ structures
that vastly affected the fertility resulted a short silique and a smaller number of seeds due to aborted
ovule or embryo. Most of these characteristics were absent in the single mutants, fh1-1 and arp3-
1, and/or were not as severe as in the double mutant. The aberrant actin cytoskeleton organizations
that were distinctive in each mutant were observed in epidermal pavement cells, trichome cells
and mesophyll cells. So, AtFH1 and AtARP3 appears to regulate several biological processes in
Arabidopsis thaliana by maintaining the proper organization of actin cytoskeleton.
Description
Keywords
AtFH1, AtARP3, Actin cytoskeleton
Citation
Degree
Master of Science (M.Sc.)
Department
Biology
Program
Biology